MySQL 5.6 Release Notes
MySQL 5.6 Release Notes
Abstract
This document contains release notes for the changes in each release of MySQL 5.6, up through MySQL 5.6.39. For
information about changes in a different MySQL series, see the release notes for that series.
For additional MySQL 5.6 documentation, see the MySQL 5.6 Reference Manual, which includes an overview of
features added in MySQL 5.6 (What Is New in MySQL 5.6), and discussion of upgrade issues that you may encounter
for upgrades from MySQL 5.5 to MySQL 5.6 (Changes Affecting Upgrades to MySQL 5.6).
Updates to these notes occur as new product features are added, so that everybody can follow the development
process. If a recent version is listed here that you cannot find on the download page (http://dev.mysql.com/
downloads/), the version has not yet been released.
The documentation included in source and binary distributions may not be fully up to date with respect to release note
entries because integration of the documentation occurs at release build time. For the most up-to-date release notes,
please refer to the online documentation instead.
For legal information, see the Legal Notices.
For help with using MySQL, please visit either the MySQL Forums or MySQL Mailing Lists, where you can discuss
your issues with other MySQL users.
For additional documentation on MySQL products, including translations of the documentation into other languages,
and downloadable versions in variety of formats, including HTML and PDF formats, see the MySQL Documentation
Library.
Document generated on: 2017-10-07 (revision: 13045)
Table of Contents
Preface and Legal Notices ................................................................................................................. 2
Changes in MySQL 5.6.39 (Not yet released, General Availability) ....................................................... 3
Changes in MySQL 5.6.38 (Not yet released, General Availability) ....................................................... 3
Changes in MySQL 5.6.37 (2017-07-17, General Availability) ............................................................... 4
Changes in MySQL 5.6.36 (2017-04-10, General Availability) ............................................................... 6
Changes in MySQL 5.6.35 (2016-12-12, General Availability) ............................................................. 11
Changes in MySQL 5.6.34 (2016-10-12, General Availability) ............................................................. 14
Changes in MySQL 5.6.33 (2016-09-06, General Availability) ............................................................. 15
Changes in MySQL 5.6.32 (2016-07-29, General Availability) ............................................................. 16
Changes in MySQL 5.6.31 (2016-06-02, General Availability) ............................................................. 18
Changes in MySQL 5.6.30 (2016-04-11, General Availability) ............................................................. 21
Changes in MySQL 5.6.29 (2016-02-05, General Availability) ............................................................. 24
Changes in MySQL 5.6.28 (2015-12-07, General Availability) ............................................................. 27
Changes in MySQL 5.6.27 (2015-09-30, General Availability) ............................................................. 29
Changes in MySQL 5.6.26 (2015-07-24, General Availability) ............................................................. 34
Changes in MySQL 5.6.25 (2015-05-29, General Availability) ............................................................. 37
Changes in MySQL 5.6.24 (2015-04-06, General Availability) ............................................................. 42
Changes in MySQL 5.6.23 (2015-02-02, General Availability) ............................................................. 46
Changes in MySQL 5.6.22 (2014-12-01, General Availability) ............................................................. 49
Changes in MySQL 5.6.21 (2014-09-23, General Availability) ............................................................. 54
Changes in MySQL 5.6.20 (2014-07-31, General Availability) ............................................................. 58
1
MySQL 5.6 Release Notes
Changes in MySQL 5.6.19 (2014-05-30, General Availability) ............................................................. 65
Changes in MySQL 5.6.18 (2014-04-11, General Availability) ............................................................. 68
Changes in MySQL 5.6.17 (2014-03-27, General Availability) ............................................................. 69
Changes in MySQL 5.6.16 (2014-01-31, General Availability) ............................................................. 75
Changes in MySQL 5.6.15 (2013-12-03, General Availability) ............................................................. 81
Changes in MySQL 5.6.14 (2013-09-20, General Availability) ............................................................. 88
Changes in MySQL 5.6.13 (2013-07-31, General Availability) ............................................................. 94
Changes in MySQL 5.6.12 (2013-06-03, General Availability) ........................................................... 104
Changes in MySQL 5.6.11 (2013-04-18, General Availability) ........................................................... 114
Changes in MySQL 5.6.10 (2013-02-05, General Availability) ........................................................... 130
Changes in MySQL 5.6.9 (2012-12-11, Release Candidate) ............................................................. 140
Changes in MySQL 5.6.8 (2012-11-07, Release Candidate) ............................................................. 149
Changes in MySQL 5.6.7 (2012-09-29, Release Candidate) ............................................................. 159
Changes in MySQL 5.6.6 (2012-08-07, Milestone 9) ........................................................................ 174
Changes in MySQL 5.6.5 (2012-04-10, Milestone 8) ........................................................................ 197
Changes in MySQL 5.6.4 (2011-12-20, Milestone 7) ........................................................................ 212
Changes in MySQL 5.6.3 (2011-10-03, Milestone 6) ........................................................................ 226
Changes in MySQL 5.6.2 (2011-04-11, Developer Milestone) ........................................................... 248
Changes in MySQL 5.6.1 (Not released, Milestone 5) ...................................................................... 260
Changes in MySQL 5.6.0 (Not released, Milestone 4) ...................................................................... 270
Index .............................................................................................................................................. 273
Preface and Legal Notices
This document contains release notes for the changes in each release of MySQL 5.6, up through MySQL
5.6.39.
Legal Notices
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If you find any errors, please report them to us in writing.
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applications. It is not developed or intended for use in any inherently dangerous applications, including
applications that may create a risk of personal injury. If you use this software or hardware in dangerous
2
MySQL 5.6 Release Notes
applications, then you shall be responsible to take all appropriate fail-safe, backup, redundancy, and other
measures to ensure its safe use. Oracle Corporation and its affiliates disclaim any liability for any damages
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to this documentation not expressly granted above.
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Changes in MySQL 5.6.39 (Not yet released, General Availability)
Version 5.6.39 has no changelog entries, or they have not been published because the product version
has not been released.
Changes in MySQL 5.6.38 (Not yet released, General Availability)
Version 5.6.38 has no changelog entries, or they have not been published because the product version
has not been released.
3
MySQL 5.6 Release Notes
Changes in MySQL 5.6.37 (2017-07-17, General Availability)
• Packaging Notes
• Security Notes
• Platform-Specific Notes
• Functionality Added or Changed
• Bugs Fixed
Packaging Notes
• mysqladmin was added to Docker/Minimal packages because it is needed by InnoDB Cluster. (Bug
#25998285)
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL Commercial Server has been updated to
version 1.0.2l. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #26160962)
Platform-Specific Notes
• Linux: The generic Linux build for MySQL 5.6 is now built on Oracle Linux 6 using glibc 2.12. Systems
that use the build need to have glibc 2.12 or later installed on them. (Bug #26005558)
Functionality Added or Changed
• For Windows, MSI installer packages now include a check for the required Visual Studio redistributable
package, and produce a message asking the user to install it if it is missing. (Bug #25658832)
• The mysql client now supports a --binary-as-hex option that causes display of binary data using
hexadecimal notation (0xvalue). Thanks to Daniël van Eeden for the patch. (Bug #25340722, Bug
#84391)
• mysqlaccess now looks for its configuration file only in the SYSCONFDIR directory and /etc. (Bug
#25043674)
Bugs Fixed
• InnoDB: The server allocated memory unnecessarily for an operation that rebuilt the table. (Bug
#25573565, Bug #85043)
• InnoDB: When using an index merge optimizer switch, a SELECT COUNT(*) operation sometimes
returned 0. Partitioning code incorrectly performed a memcpy instead of a column copy of columns read
by the index, causing the wrong records to be copied. (Bug #25332330, Bug #81031)
• Replication: A USE statement that followed a SET GTID_NEXT statement sometimes had no effect.
(Bug #26128931)
• Replication: If the binary log on a master server was rotated and a full disk condition occurred on the
partition where the binary log file was being stored, the server could stop unexpectedly. The fix adds
a check for the existence of the binary log when the dump thread switches to next binary log file. If the
4
MySQL 5.6 Release Notes
binary log is disabled, all binary logs up to the current active log are transmitted to slave and an error is
returned to the receiver thread. (Bug #25076007)
• Replication: If a relay log index file named relay log files that did not exist, RESET SLAVE ALL
sometimes did not fully clean up properly. (Bug #24901077)
• Replication: mysqlbinlog, if invoked with the --raw option, does not flush the output file until
the process terminates. But if also invoked with the --stop-never option, the process never
terminates, thus nothing is ever written to the output file. Now the output is flushed after each event.
(Bug #24609402)
• Replication: A memory leak in mysqlbinlog was fixed. The leak happened when processing fake
rotate events, or when using --raw and the destination log file could not be created. The leak only
occurred when processing events from a remote server. Thanks to Laurynas Biveinis for his contribution
to fixing this bug. (Bug #24323288, Bug #82283)
• Replication: Multi-threaded slaves could not be configured with small queue sizes using
slave_pending_jobs_size_max if they ever needed to process transactions larger than that
size. Any packet larger than slave_pending_jobs_size_max was rejected with the error
ER_MTS_EVENT_BIGGER_PENDING_JOBS_SIZE_MAX, even if the packet was smaller than the limit
set by slave_max_allowed_packet.
With this fix, slave_pending_jobs_size_max becomes a soft limit rather than a hard
limit. If the size of a packet exceeds slave_pending_jobs_size_max but is less than
slave_max_allowed_packet, the transaction is held until all the slave workers have empty
queues, and then processed. All subsequent transactions are held until the large transaction has been
completed. The queue size for slave workers can therefore be limited while still allowing occasional
larger transactions. (Bug #21280753, Bug #77406)
• mysqldump could write database names in USE statements incorrectly. (Bug #25998635)
• If the mysql_stmt_close() C API function was called, it freed memory that later could be accessed if
mysql_stmt_error(), mysql_stmt_errno(), or mysql_stmt_sqlstate() was called. To obtain
error information after a call to mysql_stmt_close(), call mysql_error(), mysql_errno(), or
mysql_sqlstate() instead. (Bug #25988681)
• Queries could be cached incorrectly, leading to incorrect query results, under these circumstances:
InnoDB table; rows are being inserted but have not yet been committed; a query uses the table as a
base table in a derived table; the optimizer chooses to materialize the derived table. (Bug #25943038,
Bug #86047)
• Man pages for a few utilities were missing from Debian/Ubuntu packages. (Bug #25811814)
• The field-t unit test failed to run with AddressSanitizer enabled. Thanks to Laurynas Biveinis for the
patch. (Bug #25803823, Bug #85678)
• Debian client packages were missing information about conflicts with native packages. (Bug #25799475)
• The Perl path in #! lines at the beginning of Perl scripts has been adjusted to /usr/local/bin/perl
for FreeBSD 11. (Bug #25719975)
• The server exited abnormally attempting to access invalid memory. (Bug #25501659)
• A race condition could occur for CREATE TABLE statements with DATA DIRECTORY or INDEX
DIRECTORY clauses. (Bug #25451091)
• MySQL compilation in different directories produced different builds to leakage of absolute paths into
debug information and __FILE__. (Bug #25436469, Bug #84608)
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MySQL 5.6 Release Notes
• mysqld_failed to start the server if the --datadir option was specified with a relative path name.
(Bug #25364806)
• With read_only enabled, creation of non-TEMPORARY tables by non-SUPER users was permitted under
certain conditions. (Bug #25250768)
• Certain stored functions, if used in a query WHERE clause, could be handled using Index Condition
Pushdown (which should not happen), resulting in a server exit. (Bug #25196653, Bug #25174454)
• On x86 machines, the uint3korr() macro read 4 bytes of data instead of the intended 3 bytes. (Bug
#24807826, Bug #83264)
• An assertion was raised during a fetch operation by the memcached plugin. (Bug #24605783)
• Queries that contained UNION in a subquery and GROUP BY could return incorrect results. (Bug
#24595639)
• LOAD XML INFILE performance became noticeably slower when the XML file being read contained a
great many spaces, such as those introduced by indenting or pretty-printing. Now all leading whitespace
is trimmed from each such value before reading it into memory. (Bug #16212207)
Changes in MySQL 5.6.36 (2017-04-10, General Availability)
• Compilation Notes
• Configuration Notes
• Packaging Notes
• Security Notes
• Thread Pool Notes
• Platform-Specific Notes
• Functionality Added or Changed
• Bugs Fixed
Compilation Notes
• Windows builds now use the default runtime libraries (builds use the /MD flag). (Bug #25611609)
• CMake support was added for compiling with Developer Studio 12.6. (Bug #25384295)
Configuration Notes
• MySQL failed to compile if -DENABLE_DEBUG_SYNC=OFF AND -DWITH_DEBUG=ON were both given.
The ENABLE_DEBUG_SYNC option has been removed and enabling WITH_DEBUG enables Debug Sync.
(Bug #18374703)
Packaging Notes
• Microsoft Windows: Reminder: MySQL 5.6 requires the Microsoft Visual C++ 2010 Redistributable
Package to run on Windows platforms. Users should make sure the package has been installed on the
system before starting the server. The package is available at the Microsoft Download Center.
• Changes in RPM package structure require a larger set of packages to be removed to install MySQL
Server cleanly. (Bug #25603087)
6
MySQL 5.6 Release Notes
• To avoid potential race conditions, Debian packages now use the GNU install utility rather than a
combination of mkdir, touch, and chown. (Bug #25258829)
• CMake-generated packaging for Debian/Ubuntu packages was refactored for improved maintainability.
The change includes updated logic for correctly replacing native distribution packaging in Debian and
Ubuntu. (Bug #25126961, Bug #25251872, Bug #84198)
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL Commercial Server has been updated to
version 1.0.2k. Issues fixed in the new OpenSSL version are described at http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #25768671, Bug #25615451, CVE-2016-7055, CVE-2017-3731,
CVE-2017-3732)
• The mysql_options() C API function now supports a MYSQL_OPT_SSL_MODE option. The only
permitted option value is SSL_MODE_REQUIRED, to require an encrypted connection to the server. It
causes mysql_real_connect() to fail if an encrypted connection cannot be obtained, without falling
back to an unencrypted connection. Thus, mysql_real_connect() returns an error if the server
does not support SSL or the client is not configured to use SSL. The client/server exchange terminates
immediately after the initial server packet has been received if the server indicates that it does not
support SSL.
To require an encrypted connection in MySQL 5.6, the standard MySQL client programs call
mysql_options() to set MYSQL_OPT_SSL_MODE if the --ssl-mode=REQUIRED command-line
option was specified. Third-party applications that must be able to require encrypted connections can
use the same technique. For details, see mysql_ssl_set().
The minor C API version number was not incremented for this change. Application programs compiled
for MySQL 5.6 that require MYSQL_OPT_SSL_MODE may fail to operate properly if the dynamic loader
provides an older client library without MYSQL_OPT_SSL_MODE. Such applications must be written
to handle this possibility by checking whether the mysql_options() call succeeds or fails. (Bug
#25575605)
Thread Pool Notes
• To improve thread_pool plugin performance, connection authentication and initialization have been
moved from the acceptor thread to the thread pool worker threads that handle client connections. This
enables the acceptor thread to handle new connections at a higher rate with reduced latency. The
INFORMATION_SCHEMA TP_THREAD_GROUP_STATE table now contains a CONNECT_THREAD_COUNT
column that indicates the number of threads that are processing or waiting to process connection
initialization and authentication. There can be a maximum of four connection threads per thread group;
these threads expire after a period of inactivity. (Bug #17159742)
Platform-Specific Notes
• Ubuntu 12.04 LTS: This is the last release in the MySQL 5.6 series to support Ubuntu 12.04 LTS. As per
the MySQL Support Lifecycle policy regarding ending support for OS versions that are obsolete or have
reached end of life, we plan to discontinue building binaries for the Linux distribution in future releases.
(Bug #25828475)
• Oracle Linux 5, Red Hat Enterprise Linux 5, and CentOS 5: This is the last release in the MySQL 5.6
series to support Oracle Linux 5, Red Hat Enterprise Linux 5, and CentOS 5. As per the MySQL Support
Lifecycle policy regarding ending support for OS versions that are obsolete or have reached end of life,
we plan to discontinue building binaries for those Linux distributions in future releases. Moreover, we
7
MySQL 5.6 Release Notes
plan to build the generic Linux tarballs for the next release on Oracle Linux 6 using glibc 2.12. (Bug
#25828375)
Functionality Added or Changed
• Replication: When a negative or fractional timeout parameter was supplied to
WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS(), the server behaved in unexpected ways. With this fix:
• A fractional timeout value is read as-is, with no round-off.
• A negative timeout value is rejected with an error if the server is on a strict SQL mode; if the server is
not on a strict SQL mode, the value makes the function return NULL immediately without any waiting
and then issue a warning.
(Bug #24976304, Bug #83537)
• The performance of UTF-8 binary collations was improved. (Bug #24788778, Bug #83247, Bug
#25076862)
• Consistency and maintainability of Debian/Ubuntu packaging maintainer scripts was improved. (Bug
#23588977)
• mysql_secure_installation is more strict about what it considers valid yes and no responses.
(Bug #13344753, Bug #62925)
Bugs Fixed
• InnoDB: The restriction that required the first undo tablespace to use space ID 1 was removed. The first
undo tablespace may now be assigned a space ID other than 1. Space ID values for undo tablespaces
are still assigned in a consecutive sequence. (Bug #25551311)
• InnoDB: Compiling the server without the Performance Schema caused a build failure. (Bug
#25348787)
• InnoDB: The file handle type name for InnoDB file I/O Performance Schema instrumentation was
changed from os_pfs_file_t to pfs_os_file_t. (Bug #25220118)
• InnoDB: A server exit on restart was caused by missing my_thread_init() and
my_thread_exit() functions for background threads that initialize the st_my_thread_var structure.
(Bug #25167032)
• InnoDB: A memcached read operation with a non-default read batch size configuration resulted in a
server exit. (Bug #25147515)
• InnoDB: Performance Schema instrumentation for InnoDB file I/O was disabled on Windows. (Bug
#14025581)
• InnoDB: The row_search_mvcc() function unnecessarily traversed the entire table for a range query,
which occurred when the record was not in the transaction read view. (Bug #84202, Bug #23481444,
Bug #25251375)
• Replication: When using a multi-threaded slave (slave_parallel_workers greater than 0) the value
of Seconds_Behind_Master was incorrect when rotating a relay log. (Bug #23532304)
• mysqldump failed to properly quote certain identifiers in SQL statements written to the dump output.
(Bug #25717383)
• Client preauthorization by the server was missing a length check for a length-encoded string. (Bug
#25714674)
8
MySQL 5.6 Release Notes
• For Debian/Ubuntu packages, user-defined collation files could be overwritten during MySQL upgrades.
Charset files are now marked as conffiles so that user customizations generate a prompt during
upgrades whether to overwrite them. (Bug #25525628, Bug #84761)
• For CREATE TABLE statements that specified the table name with a database qualifier and included a
DATA DIRECTORY or INDEX DIRECTORY option, an error occurred if there was no default database.
(Bug #25514146, Bug #84861)
• Starting the server with performance_schema_digests_size=1 caused an abnormal exit. (Bug
#25492129, Bug #84786)
• mysqld_safe did not check whether the directory named by the --basedir option existed. (Bug
#25365194)
• mysqld_safe failed if the error log file named by the --log-error option was a FIFO. (Bug
#25356221, Bug #84427)
• mysqld_safe could fail if the --datadir option value ended with a / character. (Bug #25319457)
• A recent change to mysqld_safe caused the mysql.server script to be unable to start it if the base
directory was specified as an absolute path that differed from the compiled-in default absolute path. (Bug
#25319392, Bug #84263)
• The fix for Bug #78777 had different effects depending on whether the Performance Schema is enabled.
(Bug #25309017, Bug #84305)
References: This issue is a regression of: Bug #78777.
• The CONNECTION_CONTROL plugin failed to compile if the Performance Schema was disabled. (Bug
#25308357, Bug #84304)
• For System V init scripts for RPMs, the [mysqld] option-file section was being ignored for some
options, such as pid-file. (Bug #25287707, Bug #84172)
• Init scripts failed to launch mysqld_safe if a non-default base directory was used. (Bug #25261472,
Bug #84219)
• mysqld_safe --no-defaults did not work (inadvertent consequence of an earlier bug fix). (Bug
#25244898, Bug #84173)
• Semicolon (;) characters within or between statements could cause distinct digests to be generated from
identical statements. (Bug #25244533, Bug #83253)
• For a client linked against libmysqlclient, invalid memory access could occur during use of
prepared statements. (Bug #25164932)
• The fix for Bug #25088048 caused the command used by mysqld_safe to start the MySQL server to
no longer include the mysqld path. (Bug #25144379)
References: This issue is a regression of: Bug #25088048.
• Executing a stored procedure containing a query that accessed a view could allocate memory that was
not freed until the session ended. (Bug #25053286)
• A query could produce incorrect results if the WHERE clause contained a dependent subquery, the table
had a secondary index on the columns in the select list followed by the columns in the subquery, and
GROUP BY or DISTINCT permitted the query to use a Loose Index Scan. (Bug #24671968, Bug #83005)
9
MySQL 5.6 Release Notes
• Creation of a MyISAM temporary table during query processing could fail if the key length in the query
was greater than the maximum MyISAM key length, resulting in a server exit. (Bug #24659861)
• The DebugPrintTest and DebugPrintDeathTest unit tests did not handle divide-by-zero testing
properly on the Aarch64 platform. Thanks to Alexey Kopytov for the patch. (Bug #24624555, Bug
#82889)
• Changes made to mysqld_safe in recent MySQL releases require the --ledir, --mysqld, -mysqld-version options to be specified on the command line; they can no longer be specified in
option files. This could cause failure of init scripts that invoke mysqld_safe. Such scripts now pass the
value of the MYSQLD_OPTS environment variable as the first command-line argument to mysqld_safe,
with the value set to such command line-only mysqld_safe option values as may be required. On
platforms that use systemd, the MYSQLD_OPTS value can be set in /etc/sysconfig/mysqld with a
line such as this:
MYSQLD_OPTS=" --ledir=/mysqld_ledir --mysqld=my_wrapper "
The value of MYSQLD_OPTS can also include mysqld options for mysqld_safe to pass to mysqld.
(Bug #24619033, Bug #82920)
References: This issue is a regression of: Bug #24464380, Bug #24483092, Bug #25088048, Bug
#25378439, Bug #25378565.
• For LOAD DATA used to insert data into an updateable view, the check to verify whether a column is
actually updatable was missing. (Bug #24595937)
• On Debian/Ubuntu platforms, the systemd startup script for MySQL ignored datadir settings in /etc/
mysql/my.cnf. (Bug #24517024, Bug #82709)
• A regular expression pattern match into a large string could result in a server exit due to memory
allocation failure or integer overflow. (Bug #24449076, Bug #24449090)
• An incorrect error was reported for CREATE TABLE statements with a large value for the CONNECTION
table option. The value is now limited to 1024 bytes. (Bug #24437124)
• MySQL now uses readdir() rather than readdir_r(). The latter has been deprecated since glibc
2.24 and caused debug builds of MySQL and builds using GCC 6.1 to fail.
Additionally, several problems resulting in GCC 6.1 compiler warnings were corrected. (Bug #23708395,
Bug #24437737, Bug #82515, Bug #24459890, Bug #25103242)
• The -DWITH_EDITLINE=system CMake option failed with recent versions of the editline library.
(Bug #23708332, Bug #25391997, Bug #84501)
• Grant tables with incorrect structure may cause problems in user management operations. As a
consequence of the fix for this, for any operation that modifies a grant table, the server now checks
whether the table has the expected structure and produces an error if not. mysql_upgrade must be run
to update the tables to the expected structure. (Bug #23295423, Bug #25095876, Bug #25448037)
• The QUOTE() function could allocate excessive memory. A limit of max_allowed_packet bytes is now
imposed and returns NULL with a warning for attempts to allocate more. (Bug #23195404)
• When attempting to locate the data directory, mysqld_safe incorrectly considered
$MY_BASEDIR_VERSION/var as one of the possible locations. (Bug #23013510, Bug #80866)
• The main.log_tables-big test case could be unstable on highly loaded hosts. Thanks to Laurynas
Biveinis for the patch. (Bug #22874167, Bug #80607)
10
MySQL 5.6 Release Notes
• Queries that used an aggregate function with DISTINCT could produce incorrect results. (Bug
#22686994, Bug #80310)
• With the use_index_extensions flag of the optimizer_switch system variable disabled, some
SELECT DISTINCT queries could return incorrect results. (Bug #21749123, Bug #78244)
• Debian packages were missing an AppArmor-related include file and incorrectly were marked dependent
on AppArmor (making it impossible to disable AppArmor by uninstalling it). (Bug #20768958)
• In a replication environment, SET PASSWORD or ALTER USER could fail to execute on the slave due to
failure to parse the hash string correctly. (Bug #20228478)
• On non-Linux Unix systems, the mysql.server startup script used the Linux command pidof rather
than pgrep. (Bug #13788154, Bug #64342)
• Starting multiple instances of mysqld_safe after an abnormal server exit could result in one
mysqld_safe instance killing another. As a consequence of the bug fix, the mysqld_safe.pid file is
no longer used. (Bug #11751149, Bug #41908)
• The --help message for mysqld_safe was corrected to mention that the --no-defaults, -defaults-file, and --defaults-extra-file options, if given, must be the first argument. (Bug
#11745176, Bug #11192)
• The bounds check for the XML parser position stack for each level (which has a fixed depth) used the
size of the array as the upper limit, and so was off by one. This is fixed by decreasing the allowable
depth by one, which actually matches the maximum number of elements in the position stack. (Bug
#83871, Bug #25111907)
References: See also: Bug #14040071, Bug #15948580.
• Timestamps for server-side prepared statements could be written to the binary log up to a second behind
timestamps for the corresponding nonprepared statements, leading to time value differences between
master and slave servers. (Bug #74550, Bug #19894382, Bug #25187670)
Changes in MySQL 5.6.35 (2016-12-12, General Availability)
• MySQL Enterprise Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
MySQL Enterprise Notes
• Enterprise Encryption for MySQL Enterprise Edition now enables server administrators to impose limits
on maximum key length by setting environment variables. These can be used to prevent clients from
using excessive CPU resources by passing very long key lengths to key-generation operations. For
more information, see Enterprise Encryption Usage and Examples. (Bug #19687742)
Security Notes
• Security Fix: OpenSSL is ending support for version 1.0.1 in December 2016; see https://
www.openssl.org/policies/releasestrat.html. Consequently, MySQL Commercial Server builds now use
version 1.0.2 rather than version 1.0.1, and the linked OpenSSL library for the MySQL Commercial
11
MySQL 5.6 Release Notes
Server has been updated from version 1.0.1 to version 1.0.2j. For a description of issues fixed in this
version, see https://www.openssl.org/news/vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead.
• Incompatible Change: These changes were made to mysqld_safe:
• Unsafe use of rm and chown in mysqld_safe could result in privilege escalation. chown now can be
used only when the target directory is /var/log. An incompatible change is that if the directory for
the Unix socket file is missing, it is no longer created; instead, an error occurs. Due to these changes,
/bin/bash is required to run mysqld_safe on Solaris. /bin/sh is still used on other Unix/Linux
platforms.
• The --ledir option now is accepted only on the command line, not in option files.
• mysqld_safe ignores the current working directory.
Other related changes:
• Initialization scripts that invoke mysqld_safe pass --basedir explicitly.
• Initialization scripts create the error log file only if the base directory is /var/log or /var/lib.
• Unused systemd files for SLES were removed.
(Bug #24483092, Bug #25088048, Bug #25378439, Bug #25378565)
References: See also: Bug #24464380, Bug #24388753, Bug #24619033, Bug #82920.
• MySQL Server now includes a plugin library that enables administrators to introduce an increasing delay
in server response to clients after a certain number of consecutive failed connection attempts. This
capability provides a deterrent that slows down brute force attacks that attempt to access MySQL user
accounts. For more information, see The Connection-Control Plugins.
Functionality Added or Changed
• InnoDB: By default, InnoDB reads uncommitted data when calculating statistics. In the case of
an uncommitted transaction that deletes rows from a table, InnoDB excludes records that are
delete-marked when calculating row estimates and index statistics, which can lead to non-optimal
execution plans for other transactions that are operating on the table concurrently using a transaction
isolation level other than READ UNCOMMITTED. To avoid this scenario, a new configuration option,
innodb_stats_include_delete_marked, can be enabled to ensure that InnoDB includes deletemarked records when calculating persistent optimizer statistics. (Bug #23333990)
• Unit testing now uses Google Mock 1.8. (Bug #24572381, Bug #82823)
Bugs Fixed
• Incompatible Change: A change made in MySQL 5.6.32 for handling of multibyte character sets by
LOAD DATA was reverted due to the replication incompatibility (Bug #24487120, Bug #82641)
References: See also: Bug #23080148.
• InnoDB: The GCC mach_parse_compressed function should load one to five bytes depending on the
value of the first byte. Due to a GCC bug, GCC 5 and 6 emit code to load four bytes before the first byte
value is checked (GCC Bug #77673). A workaround prevents this behavior. Thanks to Laurynas Biveinis
for the patch. (Bug #24707869, Bug #83073)
12
MySQL 5.6 Release Notes
• InnoDB: Due to a glibc bug, short-lived detached threads could exit before the caller had returned
from pthread_create(), causing a server exit. Thanks to Laurynas Biveinis for the patch. (Bug
#24605956, Bug #82886)
• InnoDB: An error during a table-rebuilding operation on a table with only a generated clustered index
(GEN_CLUST_INDEX) raised and assertion due to an error called with an invalid key name. (Bug
#24444831)
• InnoDB: On a table without an explicitly defined primary key, InnoDB did not replace the implicit
clustered index (GEN_CLUST_INDEX) when a unique key was defined on a NOT NULL column. (Bug
#24397406)
• InnoDB: InnoDB failed to free memory used by the full-text optimizer thread. (Bug #24331265)
• InnoDB: SHOW ENGINE INNODB STATUS output showed a “cleaning up” state for an idle thread.
Thread state information was not reset after statement execution. (Bug #21974225, Bug #78777)
• InnoDB: After a server restart, concurrent INSERT operations a table with an auto-increment primary
key resulted in a duplicate entry error. The current auto-increment value was not changed after
auto_increment_increment and auto_increment_offset settings were modified. (Bug
#20989615, Bug #76872)
• Replication: Tables with special DEFAULT columns, such as DEFAULT CURRENT_TIMESTAMP,
that existed only on a slave were not being updated when using row-based replication
(binlog_format=ROW). (Bug #22916743)
• Replication: Enabling semisynchronous replication when a server was during the commit stage could
cause the master to stop unexpectedly. This was related to the patch for Bug# 75570. (Bug #22202516)
• Replication: The fix for Bug #81657 was not correctly merged into MySQL 5.6. Thanks to Laurynas
Biveinis for alerting us. (Bug #83124, Bug #24715790)
• Some Linux startup scripts did not process the datadir setting correctly. (Bug #25159791)
• CREATE TABLE now requires the FILE privilege if DATA DIRECTORY or INDEX DIRECTORY is
specified explicitly as a table or partition option. ALTER TABLE requires the FILE privilege if either
option is specified explicitly as a partition option (it ignores them if specified as table options). (Bug
#25092566)
• OEL RPM packages now better detect which platforms have multilib support (for which 32-bit and 64-bit
libraries can be installed). Thanks to Alexey Kopytov for the patch. (Bug #24925181, Bug #83457)
• Compiling MySQL using Microsoft Visual Studio 2015 Version 14.0.25420.1 in relwithdebinfo mode
failed with linking errors. (Bug #24748505)
• Warnings occurring during CREATE TABLE ... SELECT could cause a server exit. (Bug #24595992)
• For segmentation faults on FreeBSD, the server did not generate a stack trace. (Bug #24566529, Bug
#23575445, Bug #81827)
• The .mylogin.cnf option file is intended for use by client programs, but the server was reading it as
well. The server no longer reads it. (Bug #24557925)
• If mysqladmin shutdown encountered an error determining the server process ID file, it displayed
an error message that did not clearly indicate the error was nonfatal. It now indicates that execution
continues. (Bug #24496214)
• The data structure used for ZEROFILL columns could experience memory corruption, leading eventually
to a server exit. (Bug #24489302)
13
MySQL 5.6 Release Notes
• Use of very long subpartition names could result in a server exit. Now partition or subpartition names
larger than 64 characters produce an ER_TOO_LONG_IDENT error. (Bug #24400628, Bug #82429)
• On Solaris, gettimeofday() could return an invalid value and cause a server shutdown. (Bug
#23499695)
• A union query resulting in tuples larger than max_join_size could result in a server exit. (Bug
#23303485)
• The optimizer could choose ref access on a secondary index rather than range access on the primary
key, even when the cost was higher. (Bug #23259872, Bug #81341)
• For some deeply nested expressions, the optimizer failed to detect stack overflow, resulting in a server
exit. (Bug #23135667)
• When taking the server offline, a race condition within the Performance Schema could lead to a server
exit. (Bug #22551677)
• The Performance Schema events_statements_summary_by_digest table could contain multiple
rows for the same statement digest and schema combination, rather than the expected single (unique)
row. (Bug #22320066, Bug #79533)
• For debug builds: Adding a unique index to a POINT NOT NULL column triggered a warning and the key
was not promoted to a primary key. Creating a unique index on a different non-NULL column in the same
table then raised an assertion. (Bug #19635706, Bug #24469860)
• Compiling using Clang 3.5 or higher with AddressSanitizer (ASAN) enabled caused the gen_lex_hash
utility to abort on Clang LeakSanitizer memory leak check failures. (Bug #76351, Bug #20720615, Bug
#22558597, Bug #80014)
• Miscalculation of memory requirements for qsort operations could result in stack overflow errors in
situations with a large number of concurrent server connections. (Bug #73979, Bug #19678930, Bug
#23224078)
Changes in MySQL 5.6.34 (2016-10-12, General Availability)
• Packaging Notes
• Security Notes
Packaging Notes
• RPM and Debian packages now create the /var/lib/mysql-files directory, which is now the
default value of the secure_file_priv system variable that specifies a directory for import and export
operations. (Bug #24709892, Bug #24761774)
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL Commercial Server has been updated to
version 1.0.1u. For a description of issues fixed in this version, see http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #24753389)
• Incompatible Change: The secure_file_priv system variable is used to limit the effect of data
import and export operations. The following changes have been made to how the server handles this
variable:
14
MySQL 5.6 Release Notes
• secure_file_priv can be set to NULL to disable all import and export operations.
• The server checks the value of secure_file_priv at startup and writes a warning to the error log
if the value is insecure. A non-NULL value is considered insecure if it is empty, or the value is the data
directory or a subdirectory of it, or a directory that is accessible by all users. If secure_file_priv is
set to a nonexistent path, the server writes an error message to the error log and exits.
• Previously, the secure_file_priv system variable was empty by default. Now the default value is
platform specific and depends on the value of the INSTALL_LAYOUT CMake option, as shown in the
following table.
INSTALL_LAYOUT Value
Default secure_file_priv Value
STANDALONE, WIN
NULL
DEB, RPM, SLES, SVR4
/var/lib/mysql-files
Otherwise
mysql-files under the CMAKE_INSTALL_PREFIX value
• To specify the default secure_file_priv value explicitly if you are building from source, use the
new INSTALL_SECURE_FILE_PRIVDIR CMake option. To specify a directory for the embedded
server, set the new INSTALL_SECURE_FILE_PRIV_EMBEDDEDDIR option. Its default value is NULL.
(Bug #24679907, Bug #24695274, Bug #24707666)
• yaSSL was upgraded to version 2.4.2. This upgrade corrects issues with: Potential AES side channel
leaks; DSA padding for unusual sizes; the SSL_CTX_load_verify_locations() OpenSSL
compatibility function failing to handle long path directory names. (Bug #24512715, Bug #24740291)
Changes in MySQL 5.6.33 (2016-09-06, General Availability)
• Compilation Notes
• Test Suite Notes
• Bugs Fixed
Compilation Notes
• CMake support was added for compiling with Developer Studio 12.5. (Bug #82249, Bug #24303829, Bug
#81274, Bug #23212938)
Test Suite Notes
• In mysql-test-run.pl, a limit of 50 was imposed on the number of workers for parallel testing, which
on systems with more than 50 CPUs resulted in exhaustion of unique thread IDs. The ID-exhaustion
problem has been corrected, and the limit of 50 on number of workers has been lifted. Thanks to Daniel
Black for the patch on which this change was based. Additionally, these changes were made:
• To avoid idle workers, the number of parallel workers now is limited to the number of tests.
• Previously, if --parallel=auto was given and the MTR_MAX_PARALLEL environment variable was
not set, a limit of 8 was imposed on the number of parallel workers. This limit has been lifted.
(Bug #22342399, Bug #79585)
Bugs Fixed
15
MySQL 5.6 Release Notes
• InnoDB: An operation that dropped and created a full-text search table raised an assertion. (Bug
#24315031)
• InnoDB: Accessing full-text search auxiliary tables while dropping the indexed table raised an assertion.
(Bug #24009272)
• InnoDB: An online DDL operation on a table with indexed BLOB columns raised an assertion during
logging of table modifications. (Bug #23760086)
• Replication: mysqlbinlog --read-from-remote-server log1 log2 was opening a new
connection for log2 without freeing the connection used for log1. Thanks to Laurynas Biveinis for the
contribution. (Bug #81675, Bug #23540182)
• Replication: With binlog_row_image=FULL, when updating single tables temporary tables were
unnecessarily being used. The fix ensures single table update follows the same pattern as multi-table
update. (Bug #79867, Bug #22510353)
• For mysqld_safe, the argument to --malloc-lib now must be one of the directories /usr/lib, /
usr/lib64, /usr/lib/i386-linux-gnu, or /usr/lib/x86_64-linux-gnu. In addition, the -mysqld and --mysqld-version options are accepted only on the command line, not in option files.
(Bug #24464380)
References: See also: Bug #24619033, Bug #82920.
• It was possible to write log files ending with .ini or .cnf that later could be parsed as option files. The
general query log and slow query log can no longer be written to a file ending with .ini or .cnf. (Bug
#24388753)
• Privilege escalation was possible by exploiting the way REPAIR TABLE used temporary files. (Bug
#24388746)
• If the basedir system variable was set at server startup from the command line or option file, the value
was not normalized (on Windows, / was not replaced with \). (Bug #23747899, Bug #82125)
• In-place ALTER TABLE operations which when executed separately caused no table rebuild could when
combined into a single statement result in a table rebuild. (Bug #23475211, Bug #81587)
• A blank server name in CREATE SERVER statements produced a server exit rather than an error. (Bug
#23295288)
• A prepared statement that used a parameter in the select list of a derived table that was part of a join
could cause a server exit. (Bug #22392374, Bug #24380263)
• MEDIUMINT columns used in operations with long integer values could result in buffer overflow. (Bug
#19984392)
• A spurious ER_NO_SUCH_TABLE error could occur when attempting to execute a prepared CREATE
TABLE ... SELECT statement that used a temporary table in the FROM clause and called a stored
function. The same error could occur for a nonprepared version of the statement if used in a stored
procedure when the procedure was re-executed. (Bug #16672723, Bug #68972)
• EINTR handling in the client library has been fixed so that interrupted read and write calls are retried.
Previously, EINTR was ignored. (Bug #82019, Bug #23703570)
Changes in MySQL 5.6.32 (2016-07-29, General Availability)
Bugs Fixed
16
MySQL 5.6 Release Notes
• Incompatible Change: For multibyte character sets, LOAD DATA could fail to allocate space correctly
and ignore input rows as a result.
A consequence of this change is that previously accepted invalid character data is now rejected, which
can cause issues if you replicate from an older server without this bug fix to a newer server with this bug
fix. For example, if an older server that accepts invalid utf8 character set data replicates to a newer
server with this bug fix, the newer server will not accept the data and replication will fail with an “Invalid
utf8 character string” error. Solutions for this issue include:
• Correct the invalid data so that it is correct for the character set
• Use a different character set for which the data is not invalid
• Upgrade the master to a version that has the bug fix so that master and slave interpret the data the
same way
(Bug #76237, Bug #20683959, Bug #23080148)
References: This issue is a regression of: Bug #14653594.
• InnoDB: Full-text search auxiliary tables could be dropped by one session while being access by
another. (Bug #23742339)
• InnoDB: Selecting full-text index information schema tables for a deleted table caused a segmentation
fault. (Bug #23479595)
• InnoDB: Rollback of a full-text index synchronization operation raised an assertion. The rollback
operation attempted to acquire a mutex still held by the background synchronization thread. (Bug
#23320569)
• InnoDB: Setting innodb_monitor_enable to all did not enable all counters. (Bug #22576241, Bug
#80083)
• Replication: An incorrectly formed server_uuid read in from auto.conf could cause an unexpected
halt. (Bug #21936933)
• Replication: After issuing a PURGE BINARY LOGS statement, if the binary log index file was not
available, for example because it had been opened by another application such as MEB, the server
could stop unexpectedly. Although this situation was rare, the handling has been made more robust to
avoid unexpected halts and more informative errors are provided. (Bug #20381055)
• Replication: When using row-based replication and InnoDB, replication slaves reverted to using an
older locking scheme when a transaction had already acquired an AUTOINC lock related to a LOAD
FILE or INSERT ... SELECT type of statement, reducing replication slave performance. The fix
ensures that sql_command is set correctly for any of the DML events such as WRITE_ROWS_EVENT,
UPDATE_EVENT, and DELETE_EVENT. (Bug #79324, Bug #22247668)
• Replication: A MySQL version 5.5 slave does not have a server_uuid and replication identified
servers by their server_id. Starting from MySQL version 5.6, replication masters detected a zombie
dump thread based only on a slave's server_uuid value, under the assumption that each slave has
a unique UUID. Connecting a MySQL 5.5 slave to a MySQL 5.6 and later master meant that the master
was unable to detect zombie dump threads that were created to serve slaves running versions older than
MySQL 5.6. The fix ensures that a master now first checks if a slave has a server_uuid set. If it is set,
zombie dump thread detection happens based on the slave's UUID. If a slave's server_uuid is not set,
zombie dump thread detection happens based on server_id. (Bug #77195, Bug #21179199)
• Replication: With slave_skip_errors enabled there were still special cases when slave errors were
not being correctly ignored. For example:
17
MySQL 5.6 Release Notes
• When opening and locking a table failed.
• When field conversions failed on a server running row-based replication.
In these cases the error was considered critical and it was not respecting the state of
slave_skip_errors. The fix ensures that with slave_skip_errors enabled, all errors reported
during applying a transaction are correctly handled. This means that in such a set up, upon receiving an
error with the log_warnings option set to greater than 1, if the error can be ignored then the warning
is printed into the error log and the server continues as it does in the case of other ignored errors. (Bug
#70640, Bug #17653275)
• Replication: When using statement-based or mixed binary logging format with --read-only=ON, it
was not possible to modify temporary tables. (Bug #62008, Bug #12818255)
References: See also: Bug #14294223, Bug #16561483.
• MySQL Server upgrades performed using RPM packages failed when upgrading from MySQL 5.5
Community to MySQL 5.6 Community or MySQL 5.5 Commercial to MySQL 5.6 Commercial. (Bug
#23736787)
• The code for reading character set information from Performance Schema statement events tables (for
example, events_statements_current) did not prevent simultaneous writing to that information. As
a result, the SQL query text character set could be invalid, which could result in a server exit. Now an
invalid character set causes SQL_TEXT column truncation. (Bug #23540008)
• A buffer overflow in the regex library was fixed. (Bug #23498283)
• Certain arguments to NAME_CONST() could cause a server exit. (Bug #23279858)
• For unit-testing with the MySQL test suite, the make unit-test command is no longer available.
The ctest program should be used instead. See http://dev.mysql.com/doc/dev/mysql-server/
PAGE_UNIT_TESTS_MAIN_TEST_RUNS.html. (Bug #23273434, Bug #81389)
• ST_Distance() could raise an assertion for NULL return values. (Bug #22760390)
• With the query cache enabled, executing a prepared statement with CURSOR_TYPE_READ_ONLY and
then again with CURSOR_TYPE_NO_CURSOR caused the server to return an error. (Bug #22559575, Bug
#80026)
• mysql_real_connect() was not thread-safe when invoked with the MYSQL_READ_DEFAULT_FILE
or MYSQL_READ_DEFAULT_GROUP option enabled. (Bug #22322504, Bug #79510)
• Installing MySQL from a yum or zypper repository resulted in /var/log/mysqld.log being created
with incorrect user and group permissions. (Bug #21879694, Bug #78512)
• If a stored function updated a view for which the view table had a trigger defined that updated another
table, it could fail and report an error that an existing table did not exist. (Bug #21142859, Bug #76808)
• If an INSTALL PLUGIN statement contained invalid UTF-8 characters in the shared library name, it
caused the server to hang (or to raise an assertion in debug builds). (Bug #14653594, Bug #23080148)
Changes in MySQL 5.6.31 (2016-06-02, General Availability)
• Packaging Notes
• Security Notes
• Functionality Added or Changed
18
MySQL 5.6 Release Notes
• Bugs Fixed
Packaging Notes
• support-files/MacOSX/ReadMe.txt is no longer included in MySQL distributions. (Bug #81038,
Bug #23088916)
• The INSTALL-SOURCE file had partly outdated information and has been removed from source
packages. (Binary packages are unaffected). (Bug #80680, Bug #23081064)
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL Commercial Server has been updated to
version 1.0.1t. For a description of issues fixed in this version, see http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #23229564)
Functionality Added or Changed
• A new CMake option, WITH_SYMVER16, if enabled, causes the libmysqlclient client library
to contain extra symbols to be compatible with libmysqlclient on RHEL/OEL 5, 6, 7, and
Fedora releases. All symbols present in libmysqlclient.so.16 are tagged with symver 16 in
libmsqlclient.so.18, making those symbols have both symver 16 and 18. (Bug #22980983)
• The version of the tcmalloc library included in MySQL distributions was very old. It has been removed
and is no longer included with MySQL. (Bug #80994, Bug #23068660)
Bugs Fixed
• InnoDB: MySQL failed to build on Fedora 24 using GCC 6. (Bug #23227804)
• InnoDB: Potential buffer overflow issues were corrected for the InnoDB memcached plugin. (Bug
#23187607)
• InnoDB: The full-text index cache was freed during a background index cache synchronization. (Bug
#22996488)
• InnoDB: A full-text index operation raised an assertion. (Bug #22963169)
• InnoDB: An INSERT operation on a table with a FULLTEXT index and FTS_DOC_ID column
failed because the inserted FTS_DOC_ID value exceeded the permitted gap between consecutive
FTS_DOC_ID values. To avoid this problem, the permitted gap between the largest used FTS_DOC_ID
value and new FTS_DOC_ID value was raised from 10000 to 65535. (Bug #22679185)
• InnoDB: With innodb_autoinc_lock_mode=0, multiple threads waiting for a table-level lock caused
an unexpected deadlock. (Bug #21983865, Bug #78761)
• InnoDB: A FLUSH TABLES ... FOR EXPORT operation appeared to stall. A loop in the
ibuf_contract_in_background function failed to exit. (Bug #21133329, Bug #77011)
• InnoDB: A full-text query raised an assertion. Under certain circumstances, DDL operations such as
ALTER TABLE ... RENAME caused full-text auxiliary tables to be removed on server restart. (Bug
#13651665)
• Replication: In the next_event() function, which is called by a slave's SQL thread to read the next
even from the relay log, the SQL thread did not release the relaylog.log_lock it acquired when it
ran into an error (for example, due to a closed relay log), causing all other threads waiting to acquire a
19
MySQL 5.6 Release Notes
lock on the relay log to hang. With this fix, the lock is released before the SQL thread leaves the function
under the situation. (Bug #21697821)
References: See also: Bug #20492319.
• Replication: When using row-based replication in a cascading or circular replication setup, where
a master is replicating to server 1 which is then replicating to server 2, merge tables were not being
correctly applied on server 2. This could cause an unexpected halt on server 2 while server 1 was
unaffected. (Bug #17018343)
• Replication: If a multi-threaded replication slave running with relay_log_recovery=1 stopped
unexpectedly, during restart the relay log recovery process could fail. This was due to transaction
inconsistencies not being filled, see Handling an Unexpected Halt of a Replication Slave. Prior to this
fix, to recover from this situation required manually setting relay_log_recovery=0, starting the slave
with START SLAVE UNTIL SQL_AFTER_MTS_GAPS to fix any transaction inconsistencies and then
restarting the slave with relay_log_recovery=1. This process has now been automated, enabling
relay log recovery of a multi-threaded slave upon restart automatically. (Bug #77496, Bug #21507981)
• Microsoft Windows: On Windows, MySQL installation could result in MySQL being placed under C:
\Program Files\Canon\Easy-WebPrint EX. (Bug #14583183)
References: See also: Bug #70918, Bug #68821, Bug #68227.
• Microsoft Windows: On Windows, MySQL installation failed if the HKEY_LOCAL_MACHINE\SOFTWARE
\Microsoft\Windows\CurrentVersion\Uninstall\ registry key was present with a key/value
pair of "InstallLocation" and "\Hewlett-Packard\\". (Bug #74631, Bug #19949163)
• INSERT with ON DUPLICATE KEY UPDATE and REPLACE on a table with a foreign key constraint
defined failed with an incorrect duplicate entry error rather than a foreign key constraint violation
error. (Bug #23135731)
References: This issue is a regression of: Bug #78853, Bug #22037930.
• For debug builds, CONCAT_WS() could raise an assertion if there was nothing to append. (Bug
#22888420)
• Invoking Enterprise Encryption functions in multiple threads simultaneously could cause a server exit.
(Bug #22839278)
• Attempting to use Enterprise Encryption functions after creating and dropping them could cause a server
exit. (Bug #22669012)
• Setting sort_buffer_size to a very large value could cause some operations to fail with an out-ofmemory error. (Bug #22594514)
• An assertion could be raised when a deadlock occurred due to a SELECT ... GROUP BY ... FOR
UPDATE query executed using a Loose Index Scan. (Bug #22187476)
• Several potential buffer overflow issues were corrected. (Bug #21977380, Bug #23187436, Bug
#23202778, Bug #23195370, Bug #23202699)
• If the CA certificate as given to the --ssl-ca option had an invalid path, yaSSL returned
an error message different from OpenSSL. Now both return SSL connection error:
SSL_CTX_set_default_verify_paths failed. (Bug #21920657)
• Some string functions returned one or a combination of their parameters as their result. If one of the
parameters had a non-ASCII character set, the result string had the same character set, resulting in
incorrect behavior when an ASCII string was expected. (Bug #18740222)
20
MySQL 5.6 Release Notes
• On Fedora 24, upgrades using a Community MySQL Server RPM failed to replace an installed MariaDB
Galera server due to a change in the MariaDB package. (Bug #81390, Bug #23273818)
• MySQL did not compile under Solaris 12 using Sun Studio. To correct this, instances of
__attribute__ were changed to MY_ATTRIBUTE. (Bug #80748, Bug #22932576)
• For a server compiled with -DWITH_PERFSCHEMA_STORAGE_ENGINE=0, a memory leak could occur for
buffered log messages used during server startup. (Bug #80089, Bug #22578574)
• For debug builds, merging a derived table into an outer query block could raise an assertion. (Bug
#79502, Bug #22305361, Bug #21139722)
• A null pointer dereference of a parser structure could occur during stored procedure name validation.
(Bug #79396, Bug #22286421)
• Using CREATE USER to create an account with the mysql_native_password or
mysql_old_password authentication plugin and using a clause of the form IDENTIFIED WITH
plugin AS 'hash_string' caused the account to be created without a password. (Bug #78033, Bug
#21616496)
• Failure of UNINSTALL PLUGIN could lead to inaccurate or confusing errors for subsequent INSTALL
PLUGIN operations. (Bug #74977, Bug #20085672)
• mysqld_multi displayed misleading error messages when it was unable to execute
my_print_defaults. (Bug #74636, Bug #19920049)
• mysqldump failed silently with no error message when it encountered an error while executing FLUSH
LOGS. (Bug #71783, Bug #18284273)
Changes in MySQL 5.6.30 (2016-04-11, General Availability)
• Security Notes
• Bugs Fixed
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL Commercial Server has been updated to
version 1.0.1s. For a description of issues fixed in this version, see http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #22685885, Bug #22923458)
• MySQL client programs now support an --ssl-mode option that enables you to specify the security
state of the connection to the server. If the option is not specified, the default value is DISABLED
(establish an unencrypted connection). --ssl-mode=REQUIRED can be specified to require an
encrypted connection, or fail if an encrypted connection cannot be obtained.
These clients support --ssl-mode: mysql, mysqladmin, mysqlcheck, mysqldump, mysqlimport,
mysqlshow, mysqlpump, mysqlslap, mysqltest, mysql_upgrade.
For more information, see Command Options for Encrypted Connections.
Note
In MySQL 5.7 and higher, the C client library provides native support for requiring
encrypted connections: call the mysql_options() C API function, passing the
21
MySQL 5.6 Release Notes
MYSQL_OPT_SSL_MODE option with a value of SSL_MODE_REQUIRED. In MySQL
5.6, the client library provides no such support because doing so would break
binary compatibility with previous library versions within the series. Clients that
require encrypted connections must implement the logic themselves.
To require encrypted connections in MySQL 5.6, the standard MySQL client
programs use this technique: If --ssl-mode=REQUIRED was specified, the
client program turns on SSL, connects to the server, and checks whether the
resulting connection is encrypted. If not, the client exits with an error. Third-party
applications that must be able to require encrypted connections can use the
same technique. For details, see mysql_ssl_set().
Bugs Fixed
• InnoDB; Partitioning: When OPTIMIZE TABLE rebuilt a partitioned InnoDB table, it placed the
resulting partition tablespace files (*.ibd files) in the default data directory instead of the directory
specified using the DATA DIRECTORY option. (Bug #75112, Bug #20160327)
• InnoDB: Running REPLACE operations on multiple connections resulted in a hang. (Bug #22530768,
Bug #79185)
• InnoDB: MySQL stalled when synchronizing the InnoDB full-text index cache. (Bug #22516559, Bug
#16510576, Bug #73816)
• InnoDB: A CREATE TABLE ... DATA DIRECTORY operation failed to create a table while
innodb_flush_method was set to O_DIRECT. (Bug #22180006, Bug #79200)
References: This issue is a regression of: Bug #21113036.
• InnoDB: The innodb_open_files setting could exceed the open files limit. (Bug #22111472)
• Replication: Issuing STOP SLAVE caused a spurious Error reading packet from server:
Lost connection to MySQL server during query message to be written to the error log. With
this fix, when connection to the master is lost, the abort_slave flag is checked and the error message
is printed only if the flag is not set. (Bug #22305605, Bug #79504)
References: See also: Bug #12977988, Bug #22290309.
• Replication: When a multi-threaded slave stopped with an error, the same error message was printed
three times. Now, the SQL thread's kill acceptance status is saved, and only printed once. (Bug
#21198611, Bug #77237)
• Replication: mysqlbinlog --verbose displayed BINARY and VARBINARY data as ordinary
strings, causing any single quote (“'”) or backslash (“\”) among the data to be printed as such, which was
confusing to the users and, in the case of a backslash, caused the next character to be skipped. This
fix makes mysqlbinlog print the characters' hexadecimal values (“\x27” for single quote and “\x5c” for
backslash) instead. (Bug #20836250)
• Replication: The test case main.merge failed when the variables binlog_format was set to “ROW,”
as the server tried to get information for table creation for a child table before it was opened. With this fix,
the server skips getting information for the table in the situation. (Bug #20574550, Bug #75976)
• Replication: If a query on a master generated an error and partial results were written to the binary log,
for example due to a DROP TABLE IF EXISTS statement applying to multiple tables that would break
foreign key constraints, when a slave configured with replication filters encountered the query it could be
incorrectly binary logged. This caused errors such as:
22
MySQL 5.6 Release Notes
Last_SQL_Error: Query caused different errors on master and slave. Error on
master: message (format)='Cannot delete or update a parent row: a foreign
key constraint fails' error code=1217 ; Error on slave: actual message='no
error', error code=0. Default database: 'db1'. Query: 'DROP TABLE IF EXISTS
`table1` /* generated by server */'
There were two fixes required for this bug.
• If a DROP TABLE statement used to drop a single table fails, to avoid partial results causing this bug
the query is not written to the binary log. If a DROP TABLE statement used to drop a list of tables fails,
any partial results it generates are written to the binary log with an error.
• When a query that generates an error as expected was received by a slave but it was skipped due
to replication filters, the slave was incorrectly checking the error. The fix for Bug #76493 ensures that
this comparison of the expected error from the master with the actual error from the slave does not
happen.
(Bug #77684, Bug #21435502)
References: See also: Bug #20797764, Bug #76493.
• Integer overflow could occur during client handshake processing, leading to a server exit. (Bug
#22722946)
• The System-V initialization script for RHEL6 or older failed to enable the mysqld service by default. (Bug
#22600974)
• When ExtractValue() found no match for the supplied expression, it returned NULL instead of an
empty string as expected.
This issue affected MySQL 5.6.28 and 5.6.29 only. (Bug #22552615)
• Improper host name checking in X509 certificates could permit man-in-the-middle attacks. (Bug
#22295186, Bug #22738607)
• A boolean mode full-text search caused a segmentation fault. (Bug #22176795)
• Concurrent selecting and flushing of a FEDERATED table while killing connections accessing it could
result in a server exit. (Bug #21918190)
• Executing GRANT PROXY statements after altering the definition of the mysql.user system table could
result in a server exit. (Bug #21699037)
• Certain error messages included part of the SQL statement that produced them, possibly exposing data.
(Bug #21682356)
• Although it is possible to create nontemporary tables using the prefix #sql, Performance Schema
assumed that tables named using this prefix were temporary and could be ignored. Performance
Schema now uses table attributes other than the name to identify temporary tables. (Bug #21105475,
Bug #22532368, Bug #79934)
• Account filtering performed by the audit_log plugin incorrectly used the account named by the
USER() function rather than the CURRENT_USER() function (the latter being the account used for
authentication). (Bug #19509471, Bug #22454245, Bug #77553)
• Character set conversion operations on NULL parameters to prepared statements could cause a server
exit. (Bug #18823979)
• Loose Index Scan was not chosen for queries that had an equality condition. (Bug #18109609)
23
MySQL 5.6 Release Notes
• A MySQL 5.6 server exited during startup if used with a 5.7 data directory due to the change in 5.7 of the
mysql.plugin table from MyISAM to InnoDB. A safe shutdown now occurs in this circumstance. (Bug
#79290, Bug #22216779)
• For INSERT and UPDATE operations that caused FOREIGN KEY constraint violations, errors were
reported rather than warnings when the IGNORE keyword was used. (Bug #78853, Bug #22037930)
References: See also: Bug #23135731.
• For some queries, an Index Merge access plan was chosen over a range scan when the cost for the
range scan was the same or less. (Bug #77209, Bug #21178196)
• Certain queries could raise an assertion when a internal string operation produced a NULL pointer rather
than an empty string. (Bug #74500, Bug #19875294, Bug #13358486, Bug #79988, Bug #22551116)
• EXPLAIN for SELECT ... FOR UPDATE statements acquired locks. (Bug #72858, Bug #18899860)
• Processlist state information was not updated correctly for LOAD DATA INFILE and could show a state
different from executing. (Bug #69375, Bug #16912362)
Changes in MySQL 5.6.29 (2016-02-05, General Availability)
• Packaging Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
Packaging Notes
• Packaging support was added for Ubuntu 15.10. (Bug #79104, Bug #22147191)
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL Commercial Server has been updated
from version 1.0.1p to version 1.0.1q. For a description of issues fixed in this version, see http://
www.openssl.org/news/vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #22348181)
• yaSSL was upgraded to version 2.3.9. This upgrade corrects an issue in which yaSSL handled only
cases of zero or one leading zeros for the key agreement instead of potentially any number, which in
rare cases could cause connections to fail when using DHE cipher suites. (Bug #22361038)
Functionality Added or Changed
• InnoDB: A new InnoDB configuration option, innodb_tmpdir, allows you to configure a separate
directory for temporary files created during online ALTER TABLE operations that rebuild the table. This
option was introduced to help avoid MySQL temporary directory overflows that could occur as a result
of large temporary files created during online ALTER TABLE operations. innodb_tmpdir can be
configured dynamically using a SET statement.
Online ALTER TABLE operations that rebuild a table also create an intermediate table file in the same
directory as the original table. The innodb_tmpdir option is not applicable to intermediate table files.
(Bug #19183565)
24
MySQL 5.6 Release Notes
• The Valgrind function signature in mysql-test/valgrind.supp was upgraded for Valgrind 3.11.
(Bug #22214867)
Bugs Fixed
• InnoDB: A small InnoDB buffer pool size with a large innodb_stats_persistent_sample_pages
setting resulted in a Difficult to find free blocks in the buffer pool warning. (Bug
#22385442)
• InnoDB: Starting the server with an empty innodb_data_home_dir entry in the configuration file
caused InnoDB to look for the buffer pool file in the root directory, resulting in a startup error. (Bug
#22016556, Bug #78831)
• InnoDB: A full-text query run under high concurrency caused a server exit due to an invalid memory
access. (Bug #21922532)
• InnoDB: With a large innodb_sort_buffer_size setting, adding an index on an empty table
performed more slowly than expected. (Bug #21762319, Bug #78262)
• Replication: When DML invokes a trigger or a stored function that inserts into an AUTO_INCREMENT
column, that DML has to be marked as an unsafe statement. If the tables are locked in the transaction
prior to the DML statement (for example by using LOCK TABLES), then the DML statement was not
being marked as an unsafe statement. The fix ensures that such DML statements are marked correctly
as unsafe. (Bug #17047208)
• Replication: As part of the fix for Bug #16290902, when writing a DROP TEMPORARY TABLE IF
EXISTS query into the binary log, the query is no longer preceded by a USE `db` statement. Instead
the query uses a fully qualified table name, for example DROP TEMPORARY TABLE IF EXISTS
`db`.`t1`;. This changed the application of replicate-rewrite-db filter rules, as they work
only on the default database specified in a USE statement. This caused slaves to fail when the
resulting CREATE TEMPORARY TABLE was applied. The fix ensures that at the time of writing a DROP
TEMPORARY TABLE IF EXISTS query into the binary log, a check is made for the default database.
If it exists then the query is written as USE default_db in the binary log. If a default database is not
present then the query is logged with the qualified table name. (Bug #77417, Bug #21317739)
• Replication: If generating a GTID for a transaction fails, the transaction is not written
to the binary log but still gets committed. Although running out of GTIDs is a rare
situation, if it did occur an error was written to the binary log as a sync stage error. With
binlog_error_action=ABORT_SERVER, the server aborts on such an error, avoiding data
inconsistency. When binlog_error_action=IGNORE_ERROR, the server continues binary logging
after such an error, potentially leading to data inconsistency between the master and the slave. The fix
changes the error to be correctly logged as a flush stage error. (Bug #77393, Bug #21276561)
• Replication: When using --gtid-mode=on , --enforce-gtid-consistency , and -binlog-format=row, if a user defined function with multiple DROP TEMPORARY TABLE
statements was executed on a master, the resulting binary log caused an error on slaves.
The fix ensures that stored functions and triggers are also considered multi-statement
transactions, and that when --enforce-gtid-consistency is enabled, functions
with CREATE TEMPORARY TABLE or DROP TEMPORARY TABLE statements generate an
ER_GTID_UNSAFE_CREATE_DROP_TEMPORARY_TABLE_IN_TRANSACTION error. (Bug #77354, Bug
#21253415)
• Replication: Stored procedure local variables that were used in an ALTER EVENT statement were
not being replicated correctly. This was related to the fact that CALL statements are not written into
the binary log. Instead each statement executed in a stored procedure is binary logged separately,
with the exception that the statement string is modified so that uses of stored procedure local variables
25
MySQL 5.6 Release Notes
are replaced with NAME_CONST('spvar_name', 'spvar-value') calls. DDL statements (which
are always binary logged in statement binary log mode irrespective of the current binary log format)
can also use stored procedure local variables and a clash could cause them to not be replicated
correctly. The fix ensures that any stored procedure local variables used in a statement are replaced with
NAME_CONST(...), except for the case when it is a DML statement and the binary log format is ROW.
(Bug #77288, Bug #21229951)
• Replication: DROP TABLE statements are regenerated by the server before being written to the binary
log. If a table or database name contained a non-regular character, such as non-latin characters, the
regenerated statement was using the wrong name, breaking replication. The fix ensures that in such a
case the regenerated name is correctly converted back to the original character set. Also during work on
this bug, it was discovered that in the rare case that a table or database name contained 64 characters,
the server was throwing an assert(M_TBLLEN < 128) assertion. The assertion has been corrected to
be less than or equal 128. (Bug #77249, Bug #21205695)
References: See also: Bug #78036, Bug #22261585, Bug #21619371.
• Replication: Irrespective of the current binlog_format setting, DDL that changes metadata on a
master is always identified and written to the binary log in STATEMENT format. Such DDL could occur
from event based SQL statements, such as CREATE EVENT or DROP EVENT, or transactions that had
unsafe functions such as sysdate(). When binlog_format=MIXED and attempting to replicate such
DDL, it was not being correctly identified and therefore was not being correctly replicated. (Bug #71859,
Bug #19286708)
• Microsoft Windows: Added Microsoft Visual Studio 2015 support. Changes include using the
native (added in VS 2015) timespec library if it exists, renamed lfind/lsearch and timezone/tzname
to avoid redefinition problems, set TMPDIR to "" by default as P_tmpdir no longer exists, deprecated
std::hash_map in favor of std::unordered_map, and added Wix Toolset 3.10 support. (Bug #21770366)
References: See also: Bug #21657078.
• Inserting a token of 84 4-byte characters into a full-text index raised an assertion. The maximum token
length was 84 characters up to a maximum of 252 bytes, which did not account for 4-byte characters.
The maximum byte length is now 336 bytes. (Bug #22291765, Bug #79475)
• If a client attempted to use an unsupported client character set (ucs2, utf16, utf32), the error
message reported to the client differed for SSL and non-SSL connections. (Bug #22216715)
• Data corruption or a server exit could occur if a stored procedure had a variable declared as TEXT or
BLOB and data was copied to that variable using SELECT ... INTO syntax from a TEXT or BLOB column.
(Bug #22203532, Bug #22232332, Bug #21941152)
• CREATE TEMPORARY TABLE .. SELECT statements involving BIT columns that resulted in a column
type redefinition could cause a server exit or an improperly created table. (Bug #21902059)
• With character_set_server=utf16le, some values of ft_boolean_syntax could cause a server
exit for full-text searches. (Bug #21631855)
• With LOCK TABLES in force, an attempt to open a temporary MERGE table consisting of a view in its list
of tables (not the last table in the list) caused a server exit. (Bug #20691429)
• For certain prepared statements, the optimizer could transform join conditions such that it used a pointer
to a temporary table field that was no longer available after the initial execution. Subsequent executions
caused a server exit. (Bug #19941403)
• Repeated execution of ALTER TABLE v1 CHECK PARTITION as a prepared statement, where v1 is a
view, led to a server exit.
26
MySQL 5.6 Release Notes
In addition, output for some administrative operations, when they are attempted on a view, changes
from “Corrupt” to “Operation failed”. These include ANALYZE TABLE, OPTIMIZE TABLE, and REPAIR
TABLE, and ALTER TABLE statements that perform ANALYZE PARTITION, CHECK PARTITION,
OPTIMIZE PARTITION, and REPAIR PARTITION operations. (Bug #19817021)
• Valgrind detected some possibly unsafe use of string functions in code used for asymmetric encryption.
(Bug #19688135)
• SSL connections ignored any change made by passing the MYSQL_OPT_READ_TIMEOUT option to the
mysql_options() C API function. (Bug #17618162)
• Solaris packages failed to note the dependency of the MySQL client library on the libstlport library.
(Bug #79778, Bug #22504264)
• Using systemd to start mysqld failed if configuration files contained multiple datadir lines. Now the
last datadir line is used. (Bug #79613, Bug #22361702)
• If server was started with --thread-handling=no-threads, no foreground thread was created for a
client connection. The Performance Schema did not account for the possibility of no foreground threads
for queries on the session_connect_attrs table, causing an assertion to be raised. (Bug #78292,
Bug #21765843)
• ALTER TABLE ... CONVERT TO CHARACTER SET operations that used the INPLACE algorithm were
ineffective if the table contained only numeric data types. Also, such operations failed to clean up their
temporary .frm file. (Bug #77554, Bug #21345391)
• Heavy SHOW PROCESSLIST or SELECT ... FROM INFORMATION_SCHEMA.PROCESSLIST activity
could result in the server accepting more than max_connections connections. (Bug #75155, Bug
#20201006)
• When used with the libmysqld embedded server, the mysql_stmt_execute() C API function
failed with a malformed communication packet error, even for simple prepared statements. (Bug
#70664, Bug #17883203)
Changes in MySQL 5.6.28 (2015-12-07, General Availability)
• Functionality Added or Changed
• Bugs Fixed
Functionality Added or Changed
• MySQL Server RPM packages now contain a conflict indicator for MySQL Connector C, such that an
error occurs when installing MySQL Server if MySQL Connector C is also installed. To install MySQL
Server, remove any MySQL Connector C packages first. (Bug #21900800)
• These client programs now support the --enable-cleartext-plugin option: mysqlcheck,
mysqldump, mysqlimport, mysqlshow. This option enables the mysql_clear_password cleartext
authentication plugin. (See Client-Side Cleartext Pluggable Authentication.) (Bug #21235226)
• Support for building with Solaris Studio 5.13 was added. (Bug #21185883)
• mysql_upgrade now attempts to print more informative errors than FATAL ERROR: Upgrade
failed. (Bug #77803, Bug #21489398)
• Performance Schema digests in DIGEST_TEXT columns have ... appended to the end to indicate
when statements exceed the maximum statement size and were truncated. This is also now done for
statement text values in SQL_TEXT columns. (Bug #75861, Bug #20519832)
27
MySQL 5.6 Release Notes
Bugs Fixed
• InnoDB: InnoDB returned an invalid corruption-related error message during an IMPORT TABLESPACE
operation. (Bug #21838158, Bug #77321)
• InnoDB: An old version of numactl headers on the build host caused a compilation error when building
a MySQL version that includes NUMA memory policy support. (Bug #21785074)
• InnoDB: An online ALTER TABLE operation caused a server exit. (Bug #21640679)
• InnoDB: A schema mismatch error occurred when importing a tablespace that was altered by DROP
INDEX operation on the source server. (Bug #21514135, Bug #77659)
• InnoDB: A duplicate key error that occurred during an online DDL operation reported an incorrect key
name. (Bug #21364096, Bug #77572)
• InnoDB: An ALTER TABLE operation caused the server to exit on disk full. (Bug #21326304, Bug
#77497)
• InnoDB: The system tablespace data file did not extend automatically when reaching the file size
limit, causing startup to fail with a size mismatch error and preventing the addition of another system
tablespace data file. (Bug #21287796, Bug #77128)
• InnoDB: Altering the letter case of a column introduced an inconsistency between the frm file and data
dictionary resulting in a failed CREATE INDEX operation on the altered column. (Bug #20755615)
• InnoDB: An ALTER TABLE operation that converted a table to an InnoDB file-per-table tablespace did
not check for unknown files with the same name as the destination .idb file, permitting an unknown file
of the same name to be overwritten. (Bug #19218794, Bug #73225)
• Replication: As binlog_error_action=ABORT_SERVER is the default in MySQL 5.7.7 and later
it is being used for more error situations. The behavior has been adjusted to generate a core dump to
improve troubleshooting possibilities. (Bug #21486161, Bug #77738)
• Replication: On a multi-threaded slave configured with master_info_repository=TABLE and
relay_log_info_repository=TABLE which had previously been run with autocommit=1,
if the slave was stopped and autocommit changed to 0, executing START SLAVE caused the
session to appear to hang. After the lock wait timeout, when START SLAVE proceeded the server
would stop unexpectedly. The fix ensures that when master_info_repository=TABLE,
relay_log_info_repository=TABLE, and autocommit=0 a new transaction is generated for start
and commit to avoid deadlocks. (Bug #21440793)
• Replication: Fatal errors encountered during flushing or synchronizing the binary log were being
ignored. Such errors are now caught and handled depending on the setting of binlog_error_action.
(Bug #76795, Bug #68953, Bug #20938915, Bug #16666407)
• Possible buffer overflow from incorrect use of strcpy() and sprintf() was corrected. (Bug
#21973610)
• MySQL RPM packages for RHEL5 failed to create the mysql system user. (Bug #21950975)
• For Debian package control files, libnuma-dev was added to Build-Depends to enable NUMA
support. (Bug #21822631)
• Selecting DECIMAL values into user-defined variables could cause a server exit. (Bug #21819304)
• Concurrent FLUSH PRIVILEGES and REVOKE or GRANT statements could produce a small time window
during which invalid memory access to proxy user information could occur, leading to a server exit. (Bug
#21602056)
28
MySQL 5.6 Release Notes
• Starting the server with the query_alloc_block_size system variable set to certain negative values
on a machine without enough memory could result in out-of-memory errors. (Bug #21503595)
• Using UNINSTALL PLUGIN to uninstall the daemon_example plugin could cause a server exit. (Bug
#21467458)
• FLUSH DES_KEY_FILE failed to reload the DES key file. (Bug #21370329)
• If an error occurred during the setup phase of subquery materialization used to compute an IN predicate,
cleanup of the temporary table did not happen, leading to Valgrind errors. (Bug #21346081)
• Queries rejected by MySQL Enterprise Firewall were truncated to 512 characters when written to the
error log. (Bug #20948270)
• A server exit could occur for the second execution of a prepared statement for which an ORDER BY
clause referred to a column position. (Bug #20755389)
• Repeated execution of a prepared statement could cause a server exit if the default database was
changed. (Bug #20447262)
• Outer references do not work as arguments to MATCH(), but the server did not properly detect them.
Now it does and raises an error. (Bug #20007383)
References: See also: Bug #21140088.
• Valgrind errors were produced during row comparator setup. (Bug #19929406)
• After failure to create a temporary table during join processing and releasing the table descriptor, an
attempt to access the now-invalid descriptor could cause a server exit. (Bug #19918299)
• Type conversion failure for DECIMAL values could cause a server exit. (Bug #19912326, Bug
#20013538)
• INSERT DELAYED could cause a server exit for tables partitioned with a character column as the key
and for which the expression required a character set conversion. (Bug #19894161)
• During a filesort for an UPDATE statement, the optimizer could access a stale pointer, resulting in a
server exit. (Bug #19893908)
• A server exit could occur when updating a view using an ALL comparison operator on a subquery that
selects from an indexed column in the main table. (Bug #19434916)
• Internal buffer sizes in resolve_stack_dump were increased to accommodate larger symbol space
requirements for C++ code. (Bug #78885, Bug #22071592)
• MySQL development RPM packages could fail to install if MySQL Connector/C development RPM
packages were installed. (Bug #78815, Bug #22005375)
• Some stress test files in the mysql-test/suite/innodb_stress directory had the executable file
mode set although they were not script files. (Bug #78403, Bug #21822413)
• The server initialization script used for the service mysql status command on Linux sometimes
incorrectly reported that the server was stopped. (Bug #77696, Bug #21768876)
Changes in MySQL 5.6.27 (2015-09-30, General Availability)
• Security Notes
• Functionality Added or Changed
29
MySQL 5.6 Release Notes
• Bugs Fixed
Security Notes
• yaSSL was upgraded to version 2.3.8.
Upgrading from older versions fixes a connection-failure issue when used with the thread pool plugin.
(Bug #20774956, Bug #21888925)
Functionality Added or Changed
• InnoDB: The new innodb_numa_interleave read-only configuration option allows you to
enable the NUMA interleave memory policy for allocation of the InnoDB buffer pool. When
innodb_numa_interleave is enabled, the NUMA memory policy is set to MPOL_INTERLEAVE for
the mysqld process. After the InnoDB buffer pool is allocated, the NUMA memory policy is set back to
MPOL_DEFAULT. This option is only available on NUMA-enabled Linux systems.
Thanks to Stewart Smith for the patch. (Bug #18871046, Bug #72811)
• RPM .spec files were updated so that MySQL Server builds from source RPM packages will include
the proper files to take advantage of operating system NUMA capabilities. This introduces a runtime
dependency on libnuma.so.1. RPM and yum detect this and refuse to install if that library is not
installed. (Bug #21775221)
Bugs Fixed
• InnoDB; Microsoft Windows: Setting lower_case_table_names=0 on a case-insensitive file system
could result in a hang condition when running an INSERT INTO ... SELECT ... FROM tbl_name
operation with the wrong tbl_name letter case. An error message is now printed and the server exits
when attempting to start the server with --lower_case_table_names=0 on a case-insensitive file
system. (Bug #20198490, Bug #75185)
• InnoDB: Reloading a table that was evicted while empty caused an AUTO_INCREMENT value to be
reset. (Bug #21454472, Bug #77743)
• InnoDB: Memory allocation sanity checks were added to the memcached code. (Bug #21288106)
• InnoDB: A memcached flush_all command raised an assertion. A function that starts a transaction
was called from within assertion code. (Bug #21239299, Bug #75199)
• InnoDB: A data corruption occurred on ARM64. GCC builtins did not issue the correct fences when
setting or unsetting the lock word. (Bug #21102971, Bug #76135)
• InnoDB: Server shutdown was delayed waiting for the purge thread to exit. To avoid this problem, the
number of calls to trx_purge() was reduced, and the trx_purge() batch size was reduced to 20.
(Bug #21040050)
• InnoDB: In READ COMMITTED mode, a REPLACE operation on a unique secondary index resulted in a
constraint violation. Thanks to Alexey Kopytov for the patch. (Bug #21025880, Bug #76927)
• InnoDB: The IBUF_BITMAP_FREE bit indicated that there was more free space in the leaf page than
was actually available. (Bug #20796566)
• InnoDB: The server failed to start with an innodb_force_recovery setting greater than 3. InnoDB
was set to read-only mode before redo logs were applied.
DROP TABLE is now supported with an innodb_force_recovery setting greater than 3. (Bug
#19779113)
30
MySQL 5.6 Release Notes
• InnoDB: The trx_sys_read_pertable_file_format_id() function reported the wrong file format.
(Bug #19206671)
• Packaging; OS X: Using user=mysql during installation on OS X did not allow the mysql database
to be installed. To fix this problem, OS X packages now use the --no-defaults option when creating
this database. This also means that having a my.cnf file on the system no longer affects the installation.
(Bug #21364902)
• Partitioning: CREATE TABLE statements that used an invalid function in a subpartitioning expression
did not always fail gracefully as expected. (Bug #20310212)
• Partitioning: Error handling for failed partitioning-related ALTER TABLE operations against nonpartitioned tables was not performed correctly (Bug #20284744)
• Partitioning: ALTER TABLE when executed from a stored procedure did not always work correctly with
tables partitioned by RANGE. (Bug #77333, Bug #16613004, Bug #21246891)
• Replication: Repeatedly checking for ERR_LOCK_WAIT_TIMEOUT (as done, for example by repeatedly
executing SHOW SLAVE STATUS) during a prolonged write lock on a table led to an assert. (Bug
#21095969)
• Replication: If statement based logging was in use, when updating multiple tables in a single statement,
a single transaction could be logged as two different transactions. This was due to the binary logging
process not properly identifying statements which were operating over transactional tables. The fix
ensures that they are correctly identified, even if such statements do not change the contents of the
tables. (Bug #16621582, Bug #21349028)
• Replication: When the dump thread was killed while dumping an inactive binary log, some events in this
log could be skipped and thus not replicated. (Bug #78337, Bug #21816399)
References: See also: Bug #74607, Bug #19975697.
• Replication: Under certain circumstances it was possible for Retrieved_Gtid_Set on the slave to
contain gaps while no gaps appeared in Executed_Gtid_Set or the slave's binary logs. This could
happen when slave rotated the relay log in such a way that the last event of this log contained the record
which set gtid_next, and was then restarted after reading GTIDs from the following log. Following the
restart, Retrieved_Gtid_Set contained GTIDs which were executed incorrectly as well as spurious or
"phantom" gaps.
TYhe fix for this problem adds a GTID to Retrieved_Gtid_Set before writing the event to the
relay log, rather than after. If for some reason writing to relay log fails, the GTID is removed from
Retrieved_Gtid_Set. (Bug #76959, Bug #21046372)
References: See also: Bug #17943188.
• Replication: SAVEPOINT and ROLLBACK TO SAVEPOINT within a trigger led to an assertion. (Bug
#76727, Bug #20901025)
• Replication: While a SHOW BINLOG EVENTS statement was executing, any parallel transaction was
blocked. The fix ensures that the SHOW BINLOG EVENTS process now only acquires a lock for the
duration of calculating the file's end position, therefore parallel transactions are not blocked for long
durations. (Bug #76618, Bug #20928790)
• Replication: If a CREATE VIEW statement failed, it was being incorrectly written to the binary log even
though it did not result in the creation of a partial view. The fix ensures that such statements are not
recorded in the binary log. Additionally it was found that when a statement which had failed on a master
was received by a slave with an expected error, if the statement was skipped on the slave, for example
31
MySQL 5.6 Release Notes
due to a replication filter, the expected error was being compared with the actual error that happened
on the slave. The fix ensures that if a statement with an expected error is received by a slave, if the
statement has not been filtered, only then is it compared with the actual error that happened on the
slave. (Bug #76493, Bug #20797764)
• Replication: The action specified for binlog_error_action was not always honored correctly after a
hardware failure occurred during log rotation. (Bug #76379, Bug #20805298)
• Replication: Modifying the master_info_repository or relay_log_info_repository inside a
transaction and later rolling back that transaction left the repository in an unusable state. We fix this by
preventing any modification of these repositories inside a transaction. (Bug #74950, Bug #20074353)
• Replication: When relay_log_recovery is set, the error log entry that reports the new recovery
positions has been extended to also report the old relay log positions. (Bug #74089, Bug #21305976)
• Replication: When a master with --binlog_checksum=none and --gtid-mode=ON was
replicating to a slave with --binlog_checksum=crc32, restarting the slave's SQL thread caused
an Event crc check error. This was due to the Format_description_log_event from
the master not being correctly found in existing relay logs after restarting the slave's SQL thread.
The fix ensures that the Previous_gtids_log_event is correctly skipped and that the correct
Format_description_log_event is found in existing relay logs after restarting the slave's SQL
thread. (Bug #73806, Bug #20644100, Bug #76746, Bug #20909880)
• Replication: When using --relay-log-info-repository=TABLE, the
mysql.slave_relay_log_info table is updated when a transaction is committed or when a flush
is performed explicitly, such as during relay log rotation. If a transaction that uses any nontransactional
tables (for example MyISAM tables) is split across multiple relay logs, it is partially committed on relay
log flush. When gtid_mode=ON, this caused the same GTID to be used for the remaining portion of the
transaction, which raised an ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error.
We fix this issue by postponing in such cases the update of the relay log information repository that
normally occurs on relay log rotation until the commit for the transaction in question has been executed.
This issue did not affect tables using transactional storage engines such as InnoDB. (Bug #68525, Bug
#16418100)
References: See also: Bug #21630907, Bug #76974.
• The CMake checks for NUMA availability could cause compilation problems on platforms without NUMA
support. (Bug #21774859)
• Certain subqueries as arguments to PROCEDURE ANALYSE() could cause a server exit. (Bug
#21350175)
• An assertion could be raised due to incorrect error handling if a SELECT ... FOR UPDATE subquery
resulted in deadlock and caused a rollback. (Bug #21096444)
• Selecting the result of an INSERT() function call to which input was passed as a hexidecimal string
could expose more information than was passed to the function. (Bug #21056907)
• The updatable property of a view is set during view creation. If the underlying table was dropped and recreated as a nonupdatable one, the updatable property of the original view was not revised accordingly.
This could cause a server exit for attempts to insert or replace into the view is made. (This problem was
specific to views with multiple tables/views and did not occur with update statements.) (Bug #21039264)
• Servers linked against yaSSL and compiled with GCC 4.8.2 could fail to respond correctly to connection
attempts until several seconds after startup. (Bug #21025377)
32
MySQL 5.6 Release Notes
• For tables with subpartitions, the server could exit due to incorrect error handling during partition pruning
if the partition could be identified but not the subpartition. (Bug #20909518)
• DELETE could check privileges for the wrong database when table aliases were used. (Bug #20777016)
• Within a trigger, use of a cursor that accessed OLD or NEW values from a row could cause a server exit.
(Bug #20760261)
• Long path name values for some options could lead to stack overflow. (Bug #20376760)
• MySQL sometimes produced no warning when it was unable to interpret a character in a given character
set. (Bug #20238729)
• On Windows, the validate_password plugin could cause a server exit during the dictionary check.
(Bug #18636874)
• On Windows, setting query_cache_min_res_unit to too large a value could result in a value of 0
and a subsequent server exit. (Bug #18487951)
• EXPLAIN of statements containing GROUP_CONCAT() could cause a server exit. (Bug #17865675)
• On Windows, heap corruption in the audit log plugin caused server startup failure. (Bug #14700102)
• RPM installation scripts failed if configuration files contained multiple datadir lines. Now the last
datadir line is used. (Bug #77878, Bug #21527467)
• For wait events, the Performance Schema uses the CYCLE timer by default, but failed to fall back to a
different timer if CYCLE was unavailable. (Bug #77577, Bug #21374104)
• Updating VARCHAR and TEXT columns in the same UPDATE statement could produce incorrect results.
When a VARCHAR column was assigned to a TEXT column and the VARCHAR column was then set to a
different value, the TEXT column's result contained the VARCHAR column's new value. (Bug #77135, Bug
#21143080)
• If an INFORMATION_SCHEMA query that performed a table-open operation encountered a corrupt
table and attempted to repair it, a deadlock could occur, resulting in an aborted transaction without
an appropriate error being reported. Such queries now do not attempt table repair. (Bug #76912, Bug
#21021848)
• mysqladmin -u root -p could exit with a segmentation fault. (Bug #76538, Bug #20802751)
• mysqlimport --use-threads did not actually use multiple threads. (Bug #76480, Bug #20772273)
• The optimizer sometimes generates an index for a derived table (subquery in the FROM clause). If this
occurred for a statement executed within a stored program, a memory leak could occur. (Bug #76349,
Bug #20728894)
• For OS X 10.9 packages, the version_compile_os system variable indicated 10.8. (Bug #75581, Bug
#20400501)
• The optimizer could incorrectly assume an out-of-memory condition while optimizing a range scan for the
OR operator, resulting in overestimation of the number of qualifying rows. (Bug #75248, Bug #20229614)
• On platforms where the char is unsigned, the server was unable to parse collation definitions that
included non-7-bit ASCII characters. Affected platforms include ARM and PowerPC. Thanks to Alexey
Kopytov for the patch. (Bug #74891, Bug #20928289, Bug #21682439)
• The events_statements_history Performance Schema table could have an ERRORS column value
of 0 when other columns indicated there were errors. (Bug #74614, Bug #19929832)
33
MySQL 5.6 Release Notes
• View creation from a UNION failed with a duplicate-column error if a SELECT statement in the UNION
other than the first used the same column name multiple times. (Bug #74539, Bug #19886430)
• Empty XML elements having the form <element/> were not handled correctly by the LOAD XML
statement. (Bug #67542, Bug #16171518)
Changes in MySQL 5.6.26 (2015-07-24, General Availability)
This release adds support for Debian 8 and Ubuntu 15.04.
• MySQL Enterprise Notes
• Performance Schema Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
MySQL Enterprise Notes
• MySQL Enterprise Edition incorporates these changes for MySQL Enterprise Firewall:
• The firewall implements a DETECTING intrusion-detection mode. For accounts in this mode, the
firewall detects suspicious statements and writes them to the error log but does not deny access.
The new Firewall_access_suspicious status variable counts the number of such statements.
The sp_set_firewall_mode() stored procedure now synchronizes between in-memory rules and
those in persistent storage for DETECTING mode, just as it does for PROTECTING mode.
• A new sp_reload_firewall_rules() stored procedure reloads the in-memory rules for a
registered account from the rules stored in the mysql.firewall_whitelist table, providing better
control over firewall operation for individual accounts.
• A new mysql_firewall_flush_status() UDF resets firewall access-counter status variables.
To upgrade MySQL Enterprise Firewall if you have a version installed from a previous release, first
uninstall the old version. Then install the new version and register your firewall configuration again. For
instructions, see Installing or Uninstalling MySQL Enterprise Firewall.
Performance Schema Notes
• Current-event timing now provides more information. Previously, while a wait, stage, or statement
event was executing, the respective tables displayed the event with TIMER_START populated, but with
TIMER_END and TIMER_WAIT as NULL:
events_waits_current
events_stages_current
events_statements_current
To make it possible to determine how how long a not-yet-completed event has been running, the timer
columns now are set as follows:
• TIMER_START is populated (unchanged from previous behavior)
• TIMER_END is populated with the current timer value
34
MySQL 5.6 Release Notes
• TIMER_WAIT is populated with the time elapsed so far (TIMER_END − TIMER_START)
To find events that have not yet completed (that is, have no END_EVENT_ID) and have taken longer
than N picoseconds thus far, monitoring applications can use this expression in queries:
WHERE END_EVENT_ID IS NULL AND TIMER_WAIT > N
(Bug #75156, Bug #20889406)
Security Notes
• Security Fix: Due to the LogJam issue (https://weakdh.org/), OpenSSL has changed the Diffie-Hellman
key length parameters for openssl-1.0.1n and up. OpenSSL has provided a detailed explanation at http://
openssl.org/news/secadv_20150611.txt. To adopt this change in MySQL, the following modifications
were made:
• The key length used in vio/viosslfactories.c for creating Diffie-Hellman keys has been
increased from 512 to 2,048 bits.
• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1m
to version 1.0.1p. Issues fixed in the new version are described at http://www.openssl.org/news/
vulnerabilities.html. This change does not affect the Oracle-produced MySQL Community build of
MySQL Server, which uses the yaSSL library instead.
(Bug #77275, Bug #21221862, Bug #18367167, Bug #21307471, Bug #21449838)
Functionality Added or Changed
• Replication: When using a multi-threaded slave, each worker thread has its own queue of transactions
to process. In previous MySQL versions, STOP SLAVE waited for all workers to process their entire
queue. This logic has been changed so that STOP SLAVE first finds the newest transaction that was
committed by any worker thread. Then, it waits for all workers to complete transactions older than that.
Newer transactions are not processed. The new logic allows STOP SLAVE to complete faster in case
some worker queues contain multiple transactions. (Bug #75525, Bug #20369401)
• Previously, the max_digest_length system variable controlled the maximum digest length for all
server functions that computed statement digests. However, whereas the Performance Schema may
need to maintain many digest values, other server functions such as MySQL Enterprise Firewall need
only one digest per session. Increasing the max_digest_length value has little impact on total
memory requirements for those functions, but can increase Performance Schema memory requirements
significantly. To enable configuring digest length separately for the Performance Schema, its digest
length is now controlled by the new performance_schema_max_digest_length system variable.
(Bug #20963147)
• Previously, changes to the validate_password plugin dictionary file (named by the
validate_password_dictionary_file system variable) while the server was running required a
restart for the server to recognize the changes. Now validate_password_dictionary_file can be
set at runtime and assigning a value causes the named file to be read without a restart.
In addition, two new status variables are available.
validate_password_dictionary_file_last_parsed indicates when the dictionary file was last
read, and validate_password_dictionary_file_words_count indicates how many words it
contains. (Bug #66697, Bug #14588145)
Bugs Fixed
35
MySQL 5.6 Release Notes
• InnoDB: The ib_cursor_moveto function did not accept a search tuple with fewer fields than are
defined for the index. (Bug #21121197, Bug #77083)
• InnoDB: The ib_table_truncate function failed to release a transaction, resulting in a hang on
server shutdown. (Bug #21121164, Bug #77084)
• InnoDB: The ib_open_table_by_id function passed an incorrect argument to
dict_table_open_on_id. (Bug #21121084, Bug #77100)
• InnoDB: On Unix-like platforms, os_file_create_simple_no_error_handling_func and
os_file_create_func opened files in different modes when innodb_flush_method was set to
O_DIRECT. (Bug #21113036, Bug #76627)
• InnoDB: Opening a foreign key-referenced table with foreign_key_checks enabled resulted in an
error when the table or database name contained special characters. (Bug #21094069, Bug #77043)
• InnoDB: The page_zip_verify_checksum function returned false for a valid compressed page. (Bug
#21086723)
• InnoDB: An ALTER TABLE ... IMPORT TABLESPACE operation on a table with prefix index failed
with a schema mismatch error. (Bug #20977779, Bug #76877)
• InnoDB: A failure to load a change buffer bitmap page during a concurrent delete tablespace operation
caused a server exit. (Bug #20878735)
• InnoDB: An assertion was raised when InnoDB attempted to dereference a NULL foreign key object.
(Bug #20762798)
• InnoDB: Importing a tablespace with a full-text index resulted in an assertion when attempting to rebuild
the index. (Bug #20637494)
• InnoDB: After dropping a full-text search index, the hidden FTS_DOC_ID and FTS_DOC_ID_INDEX
columns prevented online DDL operations. (Bug #20590013, Bug #76012)
• InnoDB: The InnoDB memcached plugin handled unsigned NOT NULL integer columns incorrectly.
Thanks to Piotr Jurkiewicz for the patch. (Bug #20535517, Bug #75864)
• InnoDB: A DROP DATABASE operation raised an assertion. (Bug #19929435)
• InnoDB: An index record was not found on rollback due to inconsistencies in the purge_node_t
structure. The inconsistency resulted in warnings and error messages such as “error in sec index entry
update”, “unable to purge a record”, and “tried to purge sec index entry not marked for deletion”. (Bug
#19138298, Bug #70214, Bug #21126772, Bug #21065746)
• Partitioning: In certain cases, ALTER TABLE ... REBUILD PARTITION was not handled correctly
when executed on a locked table. (Bug #75677, Bug #20437706)
• Replication: When using GTIDs, a multi-threaded slave which had relay_log_recovery=1 and
that stopped unexpectedly could encounter a relay-log-recovery cannot be executed when
the slave was stopped with an error or killed in MTS mode error upon restart. The fix
ensures that the relay log recovery process checks if GTIDs are in use or not. If GTIDs are in use, the
multi-threaded slave recovery process uses the GTID protocol to fill any unprocessed transactions. (Bug
#73397, Bug #19316063)
• Replication: When two slaves with the same server_uuid were configured to replicate from a single
master, the I/O thread of the slaves kept reconnecting and generating new relay log files without new
content. In such a situation, the master now generates an error which is sent to the slave. By receiving
this error from the master, the slave I/O thread does not try to reconnect, avoiding this problem. (Bug
#72581, Bug #18731252)
36
MySQL 5.6 Release Notes
• Incorrect cost calculation for the semi-join Duplicate Weedout strategy could result in a server exit. (Bug
#21184091)
• MySQL Enterprise Firewall recorded prepared statements as they were received by the server, not as
normalized digests. (Bug #20929568)
• For MySQL Enterprise Firewall operation, max_digest_length had to be larger than
mysql_firewall_max_query_size or normalized statements were truncated. The
mysql_firewall_max_query_size has been removed so that issue no longer applies, but
max_digest_length should still be set large enough to avoid statement truncation. (Bug #20894024)
• Enabling MySQL Enterprise Firewall and binary logging could result in the server reading freed memory.
(Bug #20848324)
• For large values of max_digest_length, the Performance Schema could encounter an overflow error
when computing memory requirements, resulting in a server exit. (Bug #20738072)
• The Spencer regex library used for the REGEXP operator could be subject to heap overflow in some
circumstances. (Bug #20642505)
• A buffer-overflow error could occur for mysqlslap during option parsing. (Bug #20605441)
• An off-by-one error in string-copying code could result in a buffer overflow. (Bug #20359808)
• GROUP BY or ORDER BY on a CHAR(0) NOT NULL column could lead to a server exit. (Bug
#19660891)
• For some status variables that should monotonically increase, SHOW GLOBAL STATUS in one session
could show them as decreasing when other concurrent sessions changed user or disconnected. (Bug
#18591145)
• An unnecessary memset() call invoked during Performance Schema digest operations has been
removed, which improves performance by reducing overhead. (Bug #77863, Bug #21528683)
• mysql-systemd-start failed if datadir was set in /etc/my.cnf. (Bug #77357, Bug #21262883)
• Compilation failed when building MySQL without the Performance Schema. (Bug #77292, Bug
#21229433)
• A call to the MySQL Enterprise Firewall sp_set_firewall_mode() stored procedure with an invalid
user name produced an error but added the user to the firewall_users table anyway. (Bug #76914,
Bug #21021875)
• Identifiers in normalized statements were sometimes quoted and sometimes not, an inconsistency
that caused matching failure for statement digests and digest texts. This caused problems for MySQL
Enterprise Firewall and for Performance Schema aggregation by digest. Identifiers now are quoted
consistently. (Bug #76723, Bug #20896539)
• Ubuntu packages were missing dependencies for killall and psmisc. (Bug #76716, Bug #20893836)
• On OS X 10.10 (Yosemite), mysqld failed to start automatically. The startup item has been replaced
with a launchd job, which enables the preference pane checkbox for automatic startup to work again.
(Bug #74434, Bug #19858350)
• When choosing join order, the optimizer could incorrectly calculate the cost of a table scan and choose a
table scan over a more efficient eq_ref join. (Bug #71584, Bug #18194196)
Changes in MySQL 5.6.25 (2015-05-29, General Availability)
37
MySQL 5.6 Release Notes
• MySQL Enterprise Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
MySQL Enterprise Notes
• Previously, enabling the mysql_firewall_trace system variable caused MySQL Enterprise Firewall
to write a file named firewall_trace.txt in the data directory. That is no longer done. Now with
mysql_firewall_trace enabled, for PROTECTING mode, the firewall writes rejected statements to
the error log.
Security Notes
• my_print_defaults now masks passwords. To display passwords in cleartext, use the new --show
option. (Bug #19953365, Bug #20903330)
Functionality Added or Changed
• MySQL Enterprise Firewall operates on parser states and does not work well together with the query
cache, which circumvents the parser. MySQL Enterprise Firewall now checks whether the query cache
is enabled. If so, it displays a message that the query cache must be disabled and does not load. (Bug
#20913616)
• MySQL distributions now include an innodb_stress suite of test cases. Thanks to Mark Callaghan for
the contribution. (Bug #76347, Bug #20717127)
Bugs Fixed
• InnoDB; Partitioning: The CREATE_TIME column of the INFORMATION_SCHEMA.TABLES table now
shows the correct table creation time for partitioned InnoDB tables. The CREATE_TIME column of the
INFORMATION_SCHEMA.PARTITIONS table now shows the correct partition creation time for a partition
of partitioned InnoDB tables.
The UPDATE_TIME column of the INFORMATION_SCHEMA.TABLES table now shows when a partitioned
InnoDB table was last updated by an INSERT, DELETE, or UPDATE. The UPDATE_TIME column of the
INFORMATION_SCHEMA.PARTITIONS table now shows when a partition of a partitioned InnoDB table
was last updated. (Bug #69990, Bug #17299181)
• InnoDB: An assertion was raised on shutdown due to XA PREPARE transactions holding explicit locks.
(Bug #20816223, Bug #76567)
• InnoDB: The innodb_checksum_algorithm strict_* settings (strict_none, strict_innodb,
and strict_crc32) caused the server to halt when InnoDB encountered a valid but non-matching
checksum. For example, with innodb_checksum_algorithm=strict_crc32, a valid innodb
checksum would cause the server to halt. Now, instead of halting the server, InnoDB only prints an error
message. (Bug #20568464)
• InnoDB: The memcached set command permitted a negative expire time value. Expire time is stored
internally as an unsigned integer. A negative value would be converted to a large number and accepted.
The maximum expire time value is now restricted to INT_MAX32 to prevent negative expire time values.
(Bug #20478242, Bug #75790)
• InnoDB: Removal of a foreign key object from the data dictionary cache during error handling caused
the server to exit. (Bug #20442523)
38
MySQL 5.6 Release Notes
• InnoDB: SHOW ENGINE INNODB STATUS output showed negative reservation and signal count values
due to a counter overflow error. (Bug #20417397)
• InnoDB: Failure to check the status of a cursor transaction read-only option before reusing the
cursor transaction for a write operation resulted in a server exit during a memcached workload. (Bug
#20391552)
• InnoDB: MDL locks taken by memcached clients caused a MySQL Enterprise Backup FLUSH TABLES
WITH READ LOCK operation to hang. (Bug #20275612)
• InnoDB: Estimates that were too low for the size of merge chunks in the result sorting algorithm caused
a server exit. (Bug #20049521)
• InnoDB: For full-text searches, the optimizer could choose an index that does not produce correct
relevancy rankings. (Bug #74686, Bug #19950568)
• Partitioning: When creating a partitioned table, partition-level DATA DIRECTORY or INDEX
DIRECTORY option values that contained an excessive number of characters were handled incorrectly.
(Bug #20809045)
• Partitioning: Executing an ALTER TABLE on a partitioned table on which a write lock was in effect
could cause subsequent SQL statements on this table to fail. (Bug #74288, Bug #74634, Bug
#19784790, Bug #19918805)
References: See also: Bug #19856162, Bug #74451.
• Replication: Row unpacking did not function correctly in some cases when running the server with
binlog_row_image set to minimal. (Bug #20468712)
• Replication: When binary logging was enabled, using stored functions and triggers resulting in a long
running procedure that inserted many records caused the memory use to increase rapidly. This was due
to memory being allocated per variable. The fix ensures that in such a situation, memory is allocated
once and the same memory is reused. (Bug #75879, Bug #20531812)
• Replication: If an error was encountered while adding a GTID to the received GTID set, the log lock was
not being correctly released. This could cause a deadlock. (Bug #75781, Bug #20492319)
• Replication: A slave running MySQL 5.6.24 or earlier could not connect to a master running
MySQL 5.7.6 and later that had gtid_mode=OFF_PERMISSIVE or gtid_mode=ON_PERMISSIVE.
The fix ensures that a slave running MySQL 5.6.25 and later can connect to such a master as
long as the slave's gtid_mode is compatible. In other words, a slave running MySQL 5.6.25
and later which has gtid_mode=OFF can connect to a master running MySQL 5.7.6 and
later which has gtid_mode=OFF_PERMISSIVE, and a slave running MySQL 5.6.25 and later
which has gtid_mode=ON can connect to a master running MySQL 5.7.6 and later which has
gtid_mode=ON_PERMISSIVE. Other combinations are incompatible. (Bug #75769, Bug #20471216)
• Replication: If an error occurred when using a multi-threaded slave, issuing a CHANGE MASTER
TO statement which resulted in an ER_MTS_CHANGE_MASTER_CANT_RUN_WITH_GAPS
error, and then issuing RESET SLAVE, made it impossible to change master due to repeated
ER_MTS_CHANGE_MASTER_CANT_RUN_WITH_GAPS errors. Running the debug version of mysqld
caused an unexpected exit in this case. The fix ensures that the recovery process for multi-threaded
slaves avoids this. (Bug #75574, Bug #20411374)
• Replication: When using semisynchronous replication performance was degrading when the number
of threads increased beyond a certain threshold. To improve performance, now only the thread which is
committing is responsible for deleting the active transaction node. All other operations do not touch this
active transaction list. (Bug #75570, Bug #20574628)
39
MySQL 5.6 Release Notes
• Replication: Using mysqlbinlog to process log events greater than 1.6GB failed with an out of
memory error. This was caused by an internal error converting the length variable. The fix upgrades
the length variable to avoid overflow in both encoding and decoding functions. (Bug #74734, Bug
#20350989)
• Replication: When master_info_repository=TABLE the receiver thread stores received event
information in a table. The memory used in the process of updating the table was not being freed
correctly and this could lead to an out of memory error. The fix ensures that after an event is flushed to
the relay log file by a receiver thread, the memory used is freed. (Bug #72885, Bug #19390463, Bug
#69848, Bug #20124342)
• Replication: Using mysqlbinlog to replay a relay log which ended with GTID_LOG_EVENT could
cause the following error:
ERROR 1790 (HY000) @@SESSION.GTID_NEXT cannot be changed by a client that
owns a GTID. The client owns UUID:GTID. Ownership is released on COMMIT or
ROLLBACK.
If a relay log rotate happens (either through a receiver thread restart or after issuing the ROTATE
command) exactly after writing a GTID_LOG_EVENT, when replaying such a relay log's end
ROTATE_EVENT, it was mistakenly identified as being inside a transaction, whereas the transaction
was actually started after GTID_LOG_EVENT. This caused mysqlbinlog to append SET
@@SESSION.GTID_NEXT='AUTOMATIC', resulting in two GTID_NEXT statements one after the other.
The fix ensures that mysqlbinlog generates SET @@SESSION.GTID_NEXT='AUTOMATIC' only
outside of a transaction and when there has not been a previous GTID_LOG_EVENT.
Similarly, using mysqlbinlog to concatenate and replay a relay log which contained a partial
GTID transaction caused the above error. A relay log can contain a partial GTID transaction when
AUTO_POSITION is enabled if a receiver thread is restarted when it is in the middle of transferring a
transaction from a master. On restart the slave retrieves the full transaction again. In this case, the first
relay log contains a partial GTID transaction and the second relay log contains the full GTID transaction
again. When using mysqlbinlog to concatenate such a relay log, the partial transaction was not being
correctly detected and therefore a ROLLBACK was not being correctly generated. The fix identifies partial
GTID transactions using the format description event of the second relay log, ensuring that a ROLLBACK
is correctly added. (Bug #70711, Bug #17650326)
• For small values of the read_rnd_buffer_size system variable, internal caching of temporary results
could fail and cause query execution failure. (Bug #20895852)
• The normalize_statement() UDF used by MySQL Enterprise Firewall could cause a server exit for
certain password-related statements. (Bug #20873209)
• A failed FLUSH PRIVILEGES statement followed by statements to create or drop accounts could cause
a server exit. (Bug #20857652)
• MySQL Enterprise Firewall debug code could leak memory. (Bug #20849157)
• std::stringstream code used by MySQL Enterprise Firewall could cause a server exit. (Bug
#20848536)
• SHOW VARIABLES mutexes were being locked twice, resulting in a server exit. (Bug #20788853)
• ull2dec() was modified to avoid a problem with GCC 5 in optimized mode. (Bug #20768820)
• Using GCC 5, debug builds failed due to compiler warnings. (Bug #20768717)
• The mysql_firewall_max_query_size system variable should be read only at runtime, but it was
possible to modify it. (Bug #20608993)
40
MySQL 5.6 Release Notes
• MySQL Enterprise Firewall could leak memory in the unlikely event of failure to store information in an
INFORMATION_SCHEMA table. (Bug #20593257)
• Under certain conditions, the libedit command-line library could write outside an array boundary and
cause a client program crash. (Bug #20318154)
• mysql_config_editor could exit abnormally while encrypting passwords. (Bug #20294225)
• Host value matching for the grant tables could fail to use the most specific of values that contained
wildcard characters. (Bug #20181776)
• For MySQL distributions linked against yaSSL, a corrupt client key file could cause clients to exit. (Bug
#20168526)
• For join queries with a large number of tables, the server could exit converting the join to a semi-join.
(Bug #20109861)
• Deleting rows from mysql.user following by granting privileges to a new account could result in a
server exit. (Bug #20031475)
• Renaming the mysql.procs_priv table and executing SHOW GRANTS resulted in a server exit. (Bug
#20006361)
• Within a stored procedure, access to view columns after DDL or FLUSH TABLES statements in the
procedure could cause a server exit. (Bug #19897405)
• Execution of certain BINLOG statements while temporary tables were open by HANDLER statements
could cause a server exit. (Bug #19894987, Bug #20449914)
• For a prepared statement with an ORDER BY that refers by column number to a GROUP_CONCAT()
expression that has an outer reference, repeated statement execution could cause a server exit. (Bug
#19814337)
• CMake configuration was adjusted to handle new warnings reported by Clang 3.5, using the Wpointer-bool-conversion and -Wundefined-bool-conversion compiler options. (Bug
#19584183)
• Loading corrupt spatial data into a MyISAM table could cause the server to exit during index building.
(Bug #19573096)
• Specifying --general_log_file= (with an empty value) at server startup caused the server to fail
and exit. (Bug #19392264)
• CMake configuration was adjusted to handle warnings reported by Clang 3.3. (Bug #17486216)
• Some MySQL Enterprise Firewall diagnostic messages were written outside the control of the
log_error_verbosity system variable. (Bug #76612, Bug #20848331)
• The server rejected empty COM_SHUTDOWN packets. (Bug #76552, Bug #20810928)
References: This issue is a regression of: Bug #14525642.
• A Provides rule in RPM .spec files misspelled “mysql-embedded” as “mysql-emdedded”. (Bug
#76385, Bug #20734434)
• Inappropriate -Werror options could appear in mysql_config --cflags output. (Bug #76019, Bug
#20590904)
• Using a MySQL 5.6 version of mysqladmin to change the password for an account on a MySQL 5.7.6
installation resulted in an unusable account password. (Bug #76018, Bug #20590548)
41
MySQL 5.6 Release Notes
• AddressSanitizer compilation errors were silenced. (Bug #75739, Bug #20459338, Bug #75740, Bug
#20459363)
• In the threads Performance Schema table, the PROCESSLIST_STATE and PROCESSLIST_INFO
values did not change for the thread/sql/main main thread instrument as the thread state changed.
(Bug #74517, Bug #19887143)
• Certain queries for the INFORMATION_SCHEMA TABLES and COLUMNS tables could lead to excessive
memory use when there were large numbers of empty InnoDB tables. (Bug #72322, Bug #18592390)
• Queries that included a HAVING clause based on nondeterministic functions could produce incorrect
results. (Bug #69638, Bug #17055185)
• For logging of prepared statements to the general query log, the Execute line was logged after
statement execution, not before. (Bug #69453, Bug #16953758, Bug #20536590)
• MySQL failed to compile using OpenSSL 0.9.8e. (Bug #68999, Bug #16861371)
Changes in MySQL 5.6.24 (2015-04-06, General Availability)
• MySQL Enterprise Notes
• Functionality Added or Changed
• Bugs Fixed
MySQL Enterprise Notes
• MySQL Enterprise Edition now includes MySQL Enterprise Firewall, an application-level firewall that
enables database administrators to permit or deny SQL statement execution based on matching against
whitelists of accepted statement patterns. This helps harden MySQL Server against attacks such as
SQL injection or attempts to exploit applications by using them outside of their legitimate query workload
characteristics.
Each MySQL account registered with the firewall has its own statement whitelist, enabling protection to
be tailored per account. For a given account, the firewall can operate in recording or protecting mode,
for training in the accepted statement patterns or protection against unacceptable statements. For more
information, see MySQL Enterprise Firewall.
Functionality Added or Changed
• CMake support was updated to handle CMake version 3.1. (Bug #20344207)
• The server now includes its version number when it writes the initial “starting” message to the error log,
to make it easier to tell which server instance error log output applies to. This value is the same as that
available from the version system variable. (Bug #74917, Bug #20052694)
• ALTER TABLE did not take advantage of fast alterations that might otherwise apply to the operation to
be performed, if the table contained temporal columns found to be in pre-5.6.4 format (TIME, DATETIME,
and TIMESTAMP columns without support for fractional seconds precision). Instead, it upgraded the table
by rebuilding it. Two new system variables enable control over upgrading such columns and provide
information about them:
• avoid_temporal_upgrade controls whether ALTER TABLE implicitly upgrades temporal columns
found to be in pre-5.6.4 format. This variable is disabled by default. Enabling it causes ALTER TABLE
not to rebuild temporal columns and thereby be able to take advantage of possible fast alterations.
42
MySQL 5.6 Release Notes
• show_old_temporals controls whether SHOW CREATE TABLE output includes comments to
flag temporal columns found to be in pre-5.6.4 format. Output for the COLUMN_TYPE column of the
INFORMATION_SCHEMA.COLUMNS table is affected similarly. This variable is disabled by default.
Both variables are deprecated and will be removed in a future MySQL release. (Bug #72997, Bug
#18985760)
• Statement digesting as done previously by the Performance Schema is now done at the SQL level
regardless of whether the Performance Schema is compiled in and is available to other aspects of server
operation that could benefit from it. The default space available for digesting is 1024 bytes, but can be
changed at server startup using the max_digest_length system variable.
References: See also: Bug #18304086, Bug #20015246.
Bugs Fixed
• InnoDB: A TRUNCATE TABLE operation on a temporary table raised an assertion. The temporary table
object was incompletely constructed when reloaded from SYS_TABLES. (Bug #20527363, Bug #72080)
• InnoDB: A full-text phrase search returned an incorrect result. An empty string was handled incorrectly
when tokenizing a newly inserted row. (Bug #20465273, Bug #75755)
• InnoDB: Optimizing a FULLTEXT index raised an assertion. The last optimized word of a FULLTEXT
index is stored in the CONFIG table value column which is defined as CHAR(50). An assertion was
raised when the last optimized word was greater than 50 characters in length. The CONFIG table value
column is defined as CHAR(200) as of MySQL 5.6.24 and MySQL 5.7.6.
If your innodb_ft_max_token_size setting is greater than 50, it is recommended that you recreate
existing InnoDB FULLTEXT indexes after upgrading to MySQL 5.6.24 or MySQL 5.7.6 to avoid this
issue. FULLTEXT indexes created after upgrading to MySQL 5.6.24 or MySQL 5.7.6 are unaffected.
(Bug #20418326)
• InnoDB: An InnoDB memcached extra_col_value[] array was freed without checking the allocated
flag, causing a server exit. (Bug #20400373)
• InnoDB: A DML operation performed while a flushing operation was in progress raised a memcachedrelated assertion. (Bug #20390277)
• InnoDB: The memcached process_arithmetic_command raised an assertion. The wrong error code
was returned for a nonexistent decr key. (Bug #20386835)
• InnoDB: The expiration time (exptime) defined using the memcached set command was ignored.
InnoDB memcached set the expiration time to an interval value instead of a system time value. (Bug
#20381342, Bug #70055)
• InnoDB: An assertion was raised when the full-text search fts_savepoint_release() function
released a named transaction savepoint and all subsequent savepoints. Only the initial savepoint should
be released. (Bug #20341916)
• InnoDB: A full-text search optimization operation raised an assertion. (Bug #20281800)
• InnoDB: Due to a regression introduced in MySQL 5.6.20, mysqld stop did not stop the mysqld
server process while the InnoDB memcached plugin was active. (Bug #20078646, Bug #74956)
References: This issue is a regression of: Bug #18409840.
• InnoDB: An ALTER TABLE ... RENAME failure on a table with a FULLTEXT index raised an assertion.
(Bug #20043707)
43
MySQL 5.6 Release Notes
• InnoDB: A severe error occurred during the log apply phase of an online ALTER TABLE operation
that was converting a table with a UTF-8 charset to ROW_FORMAT=REDUNDANT. (Bug #19843246, Bug
#19895661, Bug #20219871)
• InnoDB: When dummy tables are created, the autoinc_mutex member of the of the dict_table_t
object was created unnecessarily. Similarly, the zip_pad.mutex object of dict_index_t object was
created unnecessarily for dummy indexes. To avoid unnecessary mutex contention, autoinc_mutex
and zip_pad.mutex objects are now allocated and initialized on the first lock attempt. (Bug
#19788198, Bug #73361)
• InnoDB: An ALTER TABLE ... RENAME operation raised an invalid assertion. The assertion code
used an incorrect transaction object. (Bug #18523599)
References: This issue is a regression of: Bug #17447500.
• InnoDB: A memcached append operation on an INT column caused a segmentation fault. append
operations on INT columns are not supported and are now blocked. (Bug #75200, Bug #20209756)
• Partitioning: A number of ALTER TABLE statements that attempted to add partitions, columns, or
indexes to a partitioned table while a write lock was in effect for this table were not handled correctly.
(Bug #74451, Bug #74478, Bug #74491, Bug #74560, Bug #74746, Bug #74841, Bug #74860, Bug
#74869, Bug #19856162, Bug #19864284, Bug #19873019, Bug #19891663, Bug #19990815, Bug
#20026661, Bug #20031966, Bug #20033503, Bug #19827845)
• Replication: When replicating from a MySQL 5.7.6 or later server to a MySQL 5.6.23 or earlier server,
if the older version applier thread encountered an Anonymous_gtid_log_event it caused an
assert. The fix ensures that these new log events added in MySQL 5.7.6 and later do not cause this
problem with MySQL 5.6.24 and later slaves. If gtid_mode is OFF and the applier thread encounters a
Gtid_log_event, the applier thread aborts with an error. If gtid_mode is ON and the applier thread
encounters a Anonymous_gtid_log_event, the applier thread aborts with an error. (Bug #20436436)
• Replication: When the automatic_sp_privileges variable is set, the server automatically
grants the EXECUTE and ALTER ROUTINE privileges to the creator of a stored routine, if the user
does not already have these privileges. When a privileged user creates a procedure with DEFINER
as a non privileged user on a master, the current user is considered to be a privileged user and the
mysql.procs_priv table is not updated. When such a statement was replicated to slave, the
non-privileged DEFINER was considered as the current user on the slave and privileges were being
allocated. This caused a difference in the privileges that were being allocated on the master and the
slave. The fix ensures that creater of the stored routine is added to the binary log, and the slave now
checks first if the user exists before granting privileges. To maintain compatibility with previous versions,
the DEFINER is used when the INVOKER is not available. As part of this fix, anonymous users can be
used to replicate from master to slave. (Bug #20049894)
• Replication: When using a slave configured to use a special character set such as UTF-16, UTF-32,
or UCS-2, the receiver (I/O) thread failed to connect. The fix ensures that in such a situation, if a slave's
character set is not supported then default to using the latin1 character set. (Bug #19855907)
• Replication: An internal problem with binary log group commit caused an incompatibility with the
threadpool plugin. (Bug #18845301)
• Replication: When gtid_mode=ON and slave_net_timeout was set to a low value, the slave I/O
thread could appear to hang. This was due to the slave heartbeat not being sent regularly enough when
the dump thread found many events that could be skipped. The fix ensures that the heartbeat is sent
correctly in such a situation. (Bug #74607, Bug #19975697)
• CMake failed to detect the OpenSSL version properly for recent versions of OpenSSL (the format of the
version string changed). (Bug #20756770)
44
MySQL 5.6 Release Notes
• For execution of prepared statements, no check was made whether an audit log plugin returned an error,
so statement success could erroneously be returned. (Bug #20567900)
• Debian packages were missing some dependencies. (Bug #20561621)
• Following execution of a GRANT ... WITH GRANT OPTION statement, execution of a prepared
statement with a view could cause a server exit. (Bug #20030284)
• A user with a name of event_scheduler could view the Event Scheduler process list without the
PROCESS privilege. (Bug #20007583, Bug #20754369)
• Trying to create a user after dropping columns from the mysql.user table could result in a server exit.
(Bug #19910140)
• Ordering by a GROUP_CONCAT() result could cause a server exit. (Bug #19880368, Bug #20730220)
• A malformed mysql.proc table row could result in a server exit for DROP DATABASE of the database
associated with the proc row. (Bug #19875331)
• SHOW GRANTS after connecting using a proxy user could display the password hash of the proxied user.
(Bug #19817663)
• Large values of the transaction_prealloc_size system variable could cause the server to allocate
excessive amounts of memory. The maximum value has been adjusted down to 128K. A similar change
was made for transaction_alloc_block_size. Transactions can still allocate more than 128K if
necessary; this change reduces the amount that can be preallocated, as well as the maximum size of the
incremental allocation blocks. (Bug #19770858, Bug #20730053)
• Certain queries on the INFORMATION_SCHEMA.INNODB_FT_CONFIG table could cause a server exit.
(Bug #19703520)
• A server exit could occur for queries that compared two rows using the <=> operator and the rows
belonged to different character sets. (Bug #19699237, Bug #20730155)
• Certain InnoDB errors caused stored function and trigger condition handlers to be ignored. (Bug
#19683834, Bug #20094067)
• The optimizer could raise an assertion due to incorrectly associating an incorrect field with a temporary
table. (Bug #19612819, Bug #20730129)
• Audit log filtering was not applied to connection events. (Bug #19509398)
• With audit_log_connection_policy=ERRORS, successful COM_QUIT events were errroneously
written to the audit log. With audit_log_statement_policy=NONE, no connection events were
written to the audit log, regardless of the the current audit_log_connection_policy setting. (Bug
#19509373, Bug #21027210)
• The value of the Audit_log_events status variable did not equal the sum of the other audit log
counters. (Bug #19509336)
• The Audit_log_events_filtered status variable did not increment when audit log events were
filtered. (Bug #19509263)
• Many new features were added to the audit log plugin in MySQL 5.6.20, but the version number was not
increased. The version has been bumped to 1.1. (Bug #19502900)
• The server could exit due to an optimizer failure to allocate enough memory for resolving outer
references. (Bug #18782905, Bug #19892803)
45
MySQL 5.6 Release Notes
• If the audit log file was found to be corrupt at server startup, an appropriate error message was not
always written. Also, if the plugin is loaded, it will be initialized regardless of whether the log was corrupt,
except in the case that renaming the log file fails. (Bug #14584292)
• Creating a FEDERATED table with an AUTO_INCREMENT column using a LIKE clause results in a server
exit. (Bug #12671631)
• Corrections were made for a number of code issues that resulted in compiler warnings about array
bounds, possibly uninitialized variables, and variables being set but not used. (Bug #75735, Bug
#20458574)
• NULL as an expression was not recognized as a literal for calculation of Performance Schema statement
digests. (Bug #74813, Bug #20015246)
• The group_concat_max_len system variable could be set to its maximum value at runtime, but not in
an option file. (Bug #74037, Bug #19670915)
• A server warning error message referred to the obsolete table_cache system variable rather than
to table_open_cache. Thanks to Daniël van Eeden for the patch to fix some of the instances. (Bug
#73373, Bug #19285052, Bug #75081, Bug #20135780)
• In the DIGEST_TEXT column of Performance Schema statement events tables, references to system
variables of the form @@var_name were stored as @ @ var_name. (Bug #71634, Bug #18304086)
• If the WITH_SSL CMake option was specified with an incorrect path to the SSL installation or the path to
an unsupported (too old) SSL installation, the option was implicitly changed to the bundled value and
yaSSL was used instead. Now CMake exits with an error so the user knows that the option value must
be changed. (Bug #69744, Bug #17162055)
• mysql_real_connect() could close a file descriptor twice if the server was not running. (Bug #69423,
Bug #19226740)
• Notification of events for the general log were received by the audit log plugin only if the general query
log was enabled. Now notifications are posted regardless of whether the general query log is enabled.
(Bug #60782, Bug #12368204, Bug #20536590, Bug #75796, Bug #20479643)
Changes in MySQL 5.6.23 (2015-02-02, General Availability)
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
Security Notes
• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1j
to version 1.0.1k. Issues fixed in the new version are described at http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #20375530)
• yaSSL was upgraded to version 2.3.7. (Bug #19695101, Bug #20201864)
Functionality Added or Changed
• SSL 2.0 and SSL 3.0 protocols are now explicitly disabled because they provide weak encryption. (Bug
#19820550)
46
MySQL 5.6 Release Notes
References: See also: Bug #19921150.
• The valid date range of the SSL certificates in mysql-test/std_data has been extended to the year
2029. (Bug #18366947)
Bugs Fixed
• InnoDB: A tablespace export operation set the purge state to PURGE_STATE_STOP, but the purge
thread did not check the purge state until the current purge operation was completed. In the case of a
large history list, the tablespace export operation was delayed, waiting for the current purge operation to
finish. The purge state is now checked with every purge batch. (Bug #20266847, Bug #75298)
• InnoDB: An ALTER TABLE ... ADD INDEX operation raised an assertion due to assertion code that
did not allow an online index status of ONLINE_INDEX_ABORTED_DROPPED. The assertion code was
relaxed. (Bug #20198726)
• InnoDB: An error occurred when the push_warning_printf function was invoked during
server recovery. This function was previously used to print a warning message to the client. Also,
current_thd was NULL when the server was restarted. (Bug #20144839)
• InnoDB: The INNODB_METRICS adaptive_hash_searches_btree counter failed to report counter
data. (Bug #20080942, Bug #74511)
• InnoDB: An ALTER TABLE operation that changed the name of a foreign key column resulted in a
failure when reloading the foreign key constraint. The previous column name remained in the data
dictionary cache instead of being evicted. (Bug #20031243)
• InnoDB: With foreign_key_checks disabled, an assertion was raised when adding a foreign key
constraint on a renamed column that was part of a previous foreign key constraint. (Bug #20029625)
• InnoDB: Error messages regarding a size limitation on BLOB or TEXT data inserted in a single
transaction were revised. (Bug #19975322)
• InnoDB: DML operations on a table with full-text search indexes raised an invalid assertion. (Bug
#19905246)
References: This issue is a regression of: Bug #19314480.
• InnoDB: A multiple-table delete operation caused the server to halt. (Bug #19815702)
• InnoDB: A FLUSH TABLES operation raised an assertion. (Bug #19803418)
• InnoDB: With change buffering enabled, a buffered sequence of operations that should not have been
buffered resulted in an Unable to purge a record error. (Bug #19528825, Bug #73767)
• InnoDB: On non-Windows platforms, os-file_pread and os_file_pwrite functions return -1 when
an error occurs. This value was printed in an error message as the number of bytes read or written.
Instead of printing the -1 value in the error message, a separate error message indicating a system call
failure is now printed. Thanks to David Bennett for the patch. (Bug #19315210, Bug #73365)
• InnoDB: A slow shutdown (innodb_fast_shutdown=0) after crash recovery raised an assertion. Slow
shutdown did not wait for background rollback operations to finish before proceeding. (Bug #16862810)
• InnoDB: The integer column value was handled incorrectly for the memcached incr and decr
commands. (Bug #69415, Bug #20083106, Bug #74874, Bug #20044123)
• Partitioning: A failed ALTER TABLE ... TRUNCATE PARTITION statement or a failed TRUNCATE
TABLE statement against a partitioned table sometimes left inconsistent metadata in the table cache;
47
MySQL 5.6 Release Notes
subsequent SQL statements reusing this metadata failed, and could in some cases also lead to a failure
of the server. (Bug #74292, Bug #19786861)
• Replication: If a client thread on a slave executed FLUSH TABLES WITH READ LOCK while the
master executed a DML, executing SHOW SLAVE STATUS in the same client became blocked, causing
a deadlock. The fix ensures that the read lock is only held during the period that the relay log is being
updated and the deadlock is avoided. (Bug #19843808)
• Replication: Ignorable log events were introduced in MySQL 5.6, but were found to not be functioning
correctly. This has now been fixed. (Bug #74683, Bug #19949915)
• Replication: When an XA transaction was active, executing an internal rollback, for example using
the BINLOG statement, resulted in an assertion. The fix ensures that a rollback happens only for
a slave when a transaction spans multiple binary log files. Rollback does not happen now if the
Format_description comes from the BINLOG statement being executed in the MySQL client. (Bug
#74597, Bug #19928622)
• Replication: In normal usage, it is not possible for a slave to have more GTIDs than the master. But in
certain situations, such as after a hardware failure or incorrectly cleared gtid_purged, the master's
binary log could be truncated. This fix ensures that in such a situation, the master now detects that the
slave has transactions with GTIDs which are not on the master. An error is now generated on the slave
and the I/O thread is stopped with an error. The master's dump thread is also stopped. This prevents
data inconsistencies during replication. (Bug #72635, Bug #18789758)
• Replication: When using SHOW SLAVE STATUS to monitor replication performance,
Seconds_Behind_Master sometimes displayed unexpected lag behind the master. This was
caused by Previous_gtids log events being written to the slave's relay log with a timestamp behind
the master, and then being used to calculate the Seconds_Behind_Master. This fix ensures that
events generated on the slave that are added to the relay log and are not used when calculating
Seconds_Behind_Master. (Bug #72376, Bug #18622657)
• On Ubuntu 14.10, MySQL install operations could fail to reload AppArmor. (Bug #20092641)
• EXPLAIN within an XA transaction could raise an assertion. (Bug #19941492)
• Unlocking a temporary table after locking and truncating it could cause a server exit. (Bug #19786309)
• The Enterprise Encryption plugin could mishandle string arguments. (Bug #19688008, Bug #20730103)
• Binary log files created by streaming the binary log from a remote server with mysqlbinlog were given
an access mode more permissive than the original files. (Bug #19649868)
• If the audit_log plugin encountered a disk-full error, the server would exit.
Now, if the file system to which the audit log is being written fills up, a “disk full” error is written to the
error log. Audit logging continues until the audit log buffer is full. If free disk space has not been made
available by the time the buffer fills, client sessions will hang, and stopping the server at the time of client
sessions hanging will result in audit log corruption. To avoid this if client sessions are hung, ensure that
free space is available on the audit logging file system before stopping the server. (Bug #19411485)
• For failure to create a temporary table due to being out of file descriptors, the server exited rather than
returning an error. (Bug #18948649)
• For some queries that contained a derived table (subquery in the FROM clause), delay of materialization
resulted in a suboptimal execution plan due to a less accurate row-count estimate. (Bug #18607971)
• For UPDATE and DELETE statements, the server could exit after attempting to access an uninitialized
data structure. (Bug #18036143)
48
MySQL 5.6 Release Notes
• Starting the server with start service or mysqld_safe could result in failure to use the correct
plugin directory. (Bug #17619241)
• FLUSH TABLES on a FEDERATED table failed if the table had been idle longer than the wait_timeout
time plus the TCP keepalive time. (Bug #17599258)
• Selecting all columns from INFORMATION_SCHEMA.TABLES did not reopen tables if they were in the
table cache, but selecting a subset of those columns under the same conditions did reopen tables. (Bug
#16869534)
• If my_write() encountered a disk-full condition, it could return an incorrect error value. (Bug
#16078792, Bug #19984788)
• InnoDB boolean full-text searches incorrectly handled + combined with parentheses; for example,
+word1 +(>word2 <word3). (Bug #74845, Bug #20028323)
• MySQL failed to compile with GCC 4.9.1 in debug mode. (Bug #74710, Bug #19974500)
• For debug builds, the server could exit due to an optimizer failure to allocate enough memory for group
references. (Bug #74447, Bug #19855522)
• The server no longer logs the following warnings because they are uninformative: Client failed to provide
its character set. 'charset' will be used as client character set. (Bug #72543, Bug #18708334)
• A file created for an internal temporary table could cause problems if the file was orphaned for some
reason and the file name was reused for later queries. (Bug #32917, Bug #11747548)
Changes in MySQL 5.6.22 (2014-12-01, General Availability)
• Compilation Notes
• Deprecation and Removal Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
Compilation Notes
• Noisy compiler warnings on FreeBSD 10 were silenced. (Bug #18790490)
• CMake workarounds for older OS X and XCode versions were removed. On OS X, compilation always
uses Clang, even for 32-bit builds.
Compilation on OS X is now supported for OS X 10.8 and up, using XCode 5 and up. Compilation on
older versions may work but is unsupported. (Bug #18510941)
• Previously, the MYSQL_MAINTAINER_MODE CMake option was turned on by default for debug builds
and off for release builds, and MYSQL_MAINTAINER_MODE caused -Werror to be enabled when
building with GCC. This made it cumbersome to enable -Werror under certain conditions, such as
when compiling with Clang.
Now, MYSQL_MAINTAINER_MODE is on by default when compiling debug builds with GCC, and
MYSQL_MAINTAINER_MODE enbles -Werror regardless of whether GCC or Clang is used. Enabling
-Werror with Clang can be done simply by explicitly setting -DMYSQL_MAINTAINER_MODE=1 when
running CMake. In addition, some compilation warnings reported by Clang 3.4 were fixed, making it
possible to build the default debug build with -Werror. (Bug #18313717)
49
MySQL 5.6 Release Notes
• Build support was modified to produce the same warnings for Clang as for gcc. (Bug #17959689)
• CMake configuration for the Clang compiler sets more appropriate flags for building on Linux.
Specifically, -g -fno-omit-frame-pointer -fno-strict-aliasing is now added. (Bug
#17633291)
Deprecation and Removal Notes
• Replication: The global scope for the sql_log_bin system variable has been deprecated, and this
variable can now be set with session scope only. The statement SET GLOBAL SQL_LOG_BIN now
produces an error. It remains possible to read the global value of sql_log_bin, but doing so produces
a warning. You should act now to remove from your applications any dependencies on reading this
value; the global scope sql_log_bin is removed in MySQL 8.0. (Bug #67433, Bug #15868071)
Security Notes
• yaSSL was upgraded to version 2.3.5. (Bug #19695101, Bug #20201864)
• The linked OpenSSL library for the MySQL Commercial Server has been updated from version 1.0.1h
to version 1.0.1j. Issues fixed in the new version are described at http://www.openssl.org/news/
vulnerabilities.html.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server, which
uses the yaSSL library instead. (Bug #74174, Bug #19717832)
Functionality Added or Changed
• Replication: The variable binlogging_impossible_mode has been renamed
binlog_error_action. binlogging_impossible_mode is now deprecated. (Bug #19507567)
Bugs Fixed
• InnoDB: An ALTER TABLE operation raised an assertion. When a foreign key object was removed from
the dictionary cache, an incorrect foreign key object was removed from the rb-tree. (Bug #19908343)
References: This issue is a regression of: Bug #18806829.
• InnoDB: In debug builds, setting the innodb_limit_optimistic_insert_debug debug
configuration option to 1 caused an infinite B-tree page split. (Bug #19904003, Bug #74605)
• InnoDB: The dict_set_corrupted() function attempted to update the clustered index of the
SYS_INDEXES data dictionary table incorrectly. (Bug #19584379)
• InnoDB: Pages with a checksum value of zero were incorrectly treated as empty pages. A page should
only be considered empty if its checksum value and LSN field values are zero. (Bug #19500258, Bug
#73689)
References: This issue is a regression of: Bug #17335427.
• InnoDB: The InnoDB data dictionary was not updated when a ALTER TABLE ... CHANGE COLUMN
operation changed the case of the column name. (Bug #19465984)
• InnoDB: A memory access violation caused fts_optimize_thread and mysqld to terminate. (Bug
#19314480)
• InnoDB: A procedure, called from a function to perform an operation on a temporary table, caused the
server to halt. (Bug #19306524)
50
MySQL 5.6 Release Notes
• InnoDB: Attempting to shut down the server after starting the server with innodb_force_recovery=6
resulted in a hang. (Bug #19265668, Bug #73341)
• InnoDB: A COMMIT operation related to full-text search resulted in a segmentation fault. (Bug
#18503734)
• InnoDB: If a database is named using uppercase letters on a MySQL server with
lower_case_table_names=2 (which is default on OS X), InnoDB stores the database name as
specified in the InnoDB internal system table (SYS_TABLES) but stores the name in lowercase on disk.
During crash recovery, the case mismatch resulted in a conflict that marked the tablespace .ibd file
as missing. The patch for this bug converts database names to lowercase on crash recovery. (Bug
#18412598, Bug #72043)
• InnoDB: In debug builds, the InnoDB Lock Monitor asserted after a DROP TABLE operation, and the
InnoDB Monitor encountered an assertion in buf_page_get_gen. (Bug #18062698, Bug #71343, Bug
#18173184, Bug #68116)
• InnoDB: A CREATE TABLE operation that failed when innodb_strict_mode was enabled succeeded
without printing a warning when innodb_strict_mode was disabled. (Bug #17852083)
• InnoDB: For explicit cache coherency, a write barrier was added to the head of
os_thread_create_func(), and a read barrier was added to assertion code in
rw_lock_free_func(). (Bug #13364876, Bug #62692, Bug #18870970, Bug #72809)
• InnoDB: The MySQL 5.6.20 patch for Bug #16963396 / MySQL Bug #69477 limited the size
of redo log BLOB writes to 10% of the redo log file size. This limitation has been relaxed. Redo
log BLOB writes are now limited to 10% of the total redo log size (innodb_log_file_size *
innodb_log_files_in_group).
As a result, innodb_log_file_size * innodb_log_files_in_group should be 10 times larger
than the largest BLOB data size found in the rows of your tables plus the length of other variable length
fields (VARCHAR, VARBINARY, and TEXT type fields). No action is required if innodb_log_file_size
* innodb_log_files_in_group is already sufficiently large or if your tables contain no BLOB data.
(Bug #73707, Bug #19498877)
References: See also: Bug #16963396.
• Partitioning: When multiple columns are used in KEY partitioning, their order may help determine
the partition in which the row is placed. Changing this order by means of an ALTER TABLE that uses
ALGORITHM=INPLACE can lead to inconsistency when placing rows in partitions; in other words, a row
inserted before such an operation is placed in one partition, but the same row inserted afterwards is
placed in a different one. For this reason, altering the order of a multicolumn index online is no longer
allowed when that index is also used as the base for partitioning the table by KEY; instead, you must use
a copying ALTER TABLE to perform the change. (Bug #17896265)
• Replication: When using a MySQL version that had been compiled with the WITH_DEBUG option
enabled, using expire_logs_days to purge binary logs caused a restart to crash the server. This
problem arose after the fix for Bug #17283409. The fix ensures that current_thd is checked before
calling DEBUG_SYNC(). (Bug #19553099)
• Replication: Sometimes the slave I/O thread leaves a partial group in the current relay log, for
example when it is killed or stopped. After it is restarted, a new relay log is created on rotation
and a pair of ROTATE_EVENT and FORMAT_DESCRIPTION_EVENT is replicated from master and
written into the new relay log. When using a multi-threaded slave, problems such as error 1755 were
encountered when applying the remaining part of the group in the relay log. This fix ensures that if
MASTER_AUTO_POSITION is enabled, then the worker rolls back the partial group, finishes its work, and
51
MySQL 5.6 Release Notes
then applies the new complete copy of the group. If MASTER_AUTO_POSITION is disabled, the worker
does not roll back the partial group. (Bug #19545298)
• Replication: A corrupted header length in FORMAT_DESCRIPTION_LOG_EVENT could cause the server
to stop unexpectedly. This was due to FORMAT_DESCRIPTION_LOG_EVENT being considered invalid if
the header length was too short. (Bug #19145712)
• Replication: Start log events were not checked by slaves for minimum size. (Bug #19145698)
• Replication: When using row-based replication with slave_type_conversions enabled, a binary
log with more than one Rows_log_event in succession caused a crash. This was due to the temporary
tables generated as part of the slave_type_conversions process being released too early. This fix
ensures that the temporary tables are not released too early, and also ensures that long transactions do
not cause an out of memory error. (Bug #18770469, Bug #19704825)
• Replication: When using binary log files that had been manually copied from the master, for
example to avoid I/O thread reading delay, a multi-threaded slave generated error 1755. Because
the Previous_gtids log event is logged using the master's server_id and not the slave's
server_id, the previous events were not being skipped correctly. This fix ensures that the events
in Previous_gtids log event are always skipped, regardless of whether they are from the relay log
(generated on the slave) or from the binary log (generated on the master and manually copied to the
slave as the relay log). (Bug #17812024)
• Replication: When replicating from an earlier version MySQL master, such as version 4.1, checksums
are not used for events. Replicating to a slave running a newer version of MySQL, such as version 5.6,
which has slave_sql_verify_checksum enabled by default meant that the last 4 bytes of events
from the older master were being incorrectly interpreted as the checksum. A warning is now generated
and to avoid such a situation, set slave_sql_verify_checksum=0 to disable checksums on the
slave. (Bug #17276183)
• Replication: When restarting MySQL with relay_log_recovery enabled to recover from a crash,
if the SQL thread had never been started, the position from which to start recovery was not correctly
initialized because Relay_Master_Log_File was missing. This fix ensures that in such a situation
each of the relay logs, starting from the first relay log file, is searched for a rotate event from the master,
which specifies where replication started from. This rotate event is then used to set the SQL thread's
Relay_Master_Log_File and Relay_Log_Pos and recovery continues as normal. (Bug #73039,
Bug #19021091)
• Replication: When using GTIDs for replication and with MASTER_AUTO_POSITION enabled, if a
slave requested GTIDs which had been already been purged by the master, the master was sending
all available GTIDs. This happened because the master reads all available binary logs and searches
for a binary log which contains a GTID that is not contained in the union of gtid_executed and
gtid_retrieved. If such a GTID is found, the master starts sending the information starting from that
location. In a situation where the union of the slave's gtid_executed and gtid_retreived set did
not contain the master's gtid_purged set, the slave would expect GTIDs which had already been
purged by the master. This fix ensures that in such a situation, the slave's I/O thread is aborted with
an error "Master has purged binary logs containing GTIDs that the slave requires.". (Bug #73032, Bug
#19012085)
• Replication: A kernel mutex contention was being caused because mysqlbinlog was calling
localtime() for every event read, which in turn called stat(/etc/localtime). This fix ensures that
mysqlbinlog uses localtime_r(), which is optimized to store the read only timezone internal structure.
This also means that mysqlbinlog now establishes the time zone at the beginning of processing and
you can not change it during processing. This is the same behavior as MySQL server. (Bug #72701, Bug
#18808072)
• Microsoft Windows: On Windows, the replace utility did not work. (Bug #16581605)
52
MySQL 5.6 Release Notes
• The AppArmor profile installed by Debian packages was missing entries required for successful server
startup. (Bug #20057782)
• InnoDB table checksum calculation could yield an incorrect result if the value of the
innodb_checksum_algorithm system variable was modified during the operation. (Bug #19931177)
• For a materialized internal temporary table used with semi-joins, the optimizer could add an index to it
but then use an inappropriate lookup strategy, causing a server exit. (Bug #19695490, Bug #21782943)
• GROUP BY or ORDER BY on a CHAR(0) NOT NULL column could lead to a server exit. (Bug
#19660891)
• With the validate_password plugin activated and dictionary lookups enabled, passing a user-defined
variable to PASSWORD() could cause a server exit. (Bug #19388163)
• Debian packages were built using the complex set of character sets, not the all set of character sets.
(Bug #19363801)
• mysqldump failed to report a disk-full error if the dump destination was located on an NFS mount. (Bug
#18817867)
• Previously, InnoDB permitted a foreign key to be created which referenced a parent table for which
the user did not have sufficient privileges. Now, the user must have at least one of the SELECT,
INSERT, UPDATE, DELETE, or REFERENCES privileges for the parent table to create a foreign key. (Bug
#18790730)
• Copying InnoDB tables containing full-text columns from Windows to Linux caused a server exit on
Linux during full-text index initialization. (Bug #18285007, Bug #19864963, Bug #73155)
• On Debian, apt-get upgrade did not replace some packages from the repository. The workaround is
to first manually install mysql-client by running apt-get install mysql-client or directly run
apt-get dist-upgrade. (Bug #75485, Bug #20348793)
• On CentOS 6, specifying a relative path name for the --socket option caused MySQL startup script
failure. (Bug #74111, Bug #19775856)
• In Solaris 11.2, dtrace -V output changed from Sun D to Oracle D, causing detection of DTrace
availability to fail during MySQL configuration. (Bug #73826, Bug #19586917)
• mysql_config --libs_r produces output containing link flags for libmysqlclient_r, even
though that library was removed in MySQL 5.5 and replaced with a symlink to the underlying
libmysqlclient library. The output now refers directly to libmysqlclient. (The implication is that
it is no longer necessary to maintain the symlink for the sake of being able to use mysql_config -libs_r.) (Bug #73724, Bug #19506315)
• For statement digest calculation, the Performance Schema failed to recognize signed literal numbers as
values representable by ? and created multiple digests for statements that should have had the same
signature. Now all instances of unary plus and unary minus followed by a number reduce to ? in digests.
(Bug #73504, Bug #19389709)
• Compilation on Windows using Visual Studio 2013 resulted in “unresolved external symbol” errors. (Bug
#73461, Bug #19351573)
• OLD_PASSWORD() is deprecated, but no warning was produced when it was invoked. (Bug #73376, Bug
#19285177)
• Certain queries for which subquery materialization or UNION DISTINCT was used together with a hash
index on a temporary table could produce incorrect results or cause a server exit. (Bug #73368, Bug
#19297190)
53
MySQL 5.6 Release Notes
• The IS_FREE_LOCK() and IS_USED_LOCK() function implementations contained a race condition
due to which they could access freed memory when a user lock was concurrently checked and freed.
Accessing freed memory could result in an incorrect function return value or server exit. (Bug #73123,
Bug #19070633)
• LOCK TABLES sometimes acquired an insufficiently strong lock for implicitly locked tables. (Bug #72887,
Bug #18913551)
• The ENABLED_LOCAL_INFILE CMake option incorrectly was enabled by default. (Bug #72106, Bug
#18448743)
• Use of ODBC-format date literals could produce incorrect query results. (Bug #69233, Bug #16812821)
• mysql_install_db ignored option files in the default locations. (Bug #68807, Bug #16570238)
• mysql_setpermission failed to properly quote user names in SQL statements that it generated. (Bug
#66317, Bug #14486004)
Changes in MySQL 5.6.21 (2014-09-23, General Availability)
• InnoDB Notes
• MySQL Enterprise Notes
• Functionality Added or Changed
• Bugs Fixed
InnoDB Notes
• The --skip-innodb option is now deprecated and its use results in a warning. It will be removed in a
future MySQL release. This also applies to its synonyms (--innodb=OFF, --disable-innodb, and
so forth).
MySQL Enterprise Notes
• MySQL Enterprise Edition now includes a set of encryption functions based on the OpenSSL library
that expose OpenSSL capabilities at the SQL level. These functions enable Enterprise applications to
perform the following operations:
• Implement added data protection using public-key asymmetric cryptography
• Create public and private keys and digital signatures
• Perform asymmetric encryption and decryption
• Use cryptographic hashing for digital signing and data verification and validation
For more information, see MySQL Enterprise Encryption Functions.
Functionality Added or Changed
• Replication: The new variable simplified_binlog_gtid_recovery can be used to change the
way binary log files are searched for previous GTIDs during recovery, speeding up the process when a
large number of binary log files exist. (Bug #69097, Bug #16741603, Bug #74071, Bug #19686914)
• Internally, spatial data types such as Geometry are represented as BLOB values, so when invoked with
the --hex-blob option, mysqldump now displays spatial values in hex. (Bug #43544, Bug #11752369)
54
MySQL 5.6 Release Notes
Bugs Fixed
• InnoDB; Partitioning: Large numbers of partitioned InnoDB tables could consume much more memory
when used in MySQL 5.6 or 5.7 than the memory used by the same tables used in previous releases of
the MySQL Server. (Bug #17780517, Bug #70641)
References: This issue is a regression of: Bug #11764622, Bug #57480.
• InnoDB: An ALTER TABLE ... ADD FOREIGN KEY operation could cause a serious error. (Bug
#19471516, Bug #73650)
• InnoDB: In debug builds, an INSERT operation affecting compressed tables would raise a sync-related
assertion. (Bug #19295893)
• InnoDB: Retrieval of multiple values with a single get command would return incorrect results instead of
an error message. The InnoDB memcached plugin does not currently support retrieval of multiple values
with a single get command. (Bug #19172212, Bug #72453)
• InnoDB: Attempting to perform operations on a timed out key would cause the memcached daemon to
crash and restart. (Bug #19172013, Bug #72586)
• InnoDB: With a transaction isolation level less than or equal to READ COMMITTED, gap locks were not
taken when scanning a unique secondary index to check for duplicates. As a result, duplicate check logic
failed allowing duplicate key values in the unique secondary index. (Bug #19140907)
References: This issue is a regression of: Bug #16133801.
• InnoDB: During recovery, a segmentation fault would occur when marking a table as corrupt. (Bug
#18942294)
References: This issue is a regression of: Bug #11830883.
• InnoDB: A failed in-place ALTER TABLE operation would leave behind non-unique temporary file names
in the data dictionary preventing future ALTER TABLE operations on the same table due to temporary
file name conflicts. To avoid this problem, temporary file names are made unique by appending a
static global number that is initialized to a random distributed 32-bit number using ut_time() and
ut_crc32(). The number is then incremented atomically for each assigned temporary file name.
Previously, temporary files were named using the format #sql-ibtid, where tid is the table ID.
Temporary files are now named using the format #sql-ibtid-inc, where tid is the table ID and inc
is the incremented number. (Bug #18734396, Bug #72594)
• InnoDB: In rare cases, the purge process would attempt to delete a secondary index record that was not
marked for deletion, resulting in an inconsistent secondary index. (Bug #18631496)
• InnoDB: srv_active_wake_master_thread() was called directly in innobase_commit and
innobase_prepare, waking up the master thread and incrementing srv_activity_count.
srv_active_wake_master_thread() should only be called after committing write
transactions, not after read-only transactions or rollbacks. This patch also replaces some calls to
srv_active_wake_master_thread() with calls to ib_wake_master_thread(). (Bug #18477009,
Bug #72137)
• InnoDB: An in-place ALTER TABLE operation on a table with a broken foreign key constraint could raise
an assertion. (Bug #16869435)
• InnoDB: Inserting a record into an InnoDB table with a key that falls between the maximum key of a full
page and the minimum key of the “next” page could result in unnecessary page splits and under-filled
pages. If the insert point is at the end of a page, InnoDB now attempts to insert to the next page before
splitting the page. (Bug #15923864, Bug #67718)
55
MySQL 5.6 Release Notes
• Replication: After the fix for Bug #16861624, killing a multi-threaded slave worker which was waiting for
a commit lock caused a debug assertion to fail. This fix ensures that such a situation can not occur. (Bug
#19311260)
• Replication: When committing a transaction, a flag is now used to check whether a thread has been
created, rather than checking the thread itself, which uses more resources, particularly when running the
server with master_info_repository=TABLE. (Bug #18684222)
References: See also: Bug #17967378.
• Replication: When using GTIDs with MASTER_AUTO_POSITION enabled, if an I/O thread was restarted
it failed with an ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error due to a partial transaction not being
correctly rolled back before resuming the I/O thread. This fix ensures that the partial transaction is
correctly rolled back. (Bug #18472603)
• Replication: When mysqlbinlog processed multiple binary log files into a single output file,
this file was not in a useful state for point-in-time recovery, when it failed with the error, When
@@SESSION.GTID_NEXT is set to a GTID, you must explicitly set it to a
different value after a COMMIT or ROLLBACK. Please check GTID_NEXT variable
manual page for detailed explanation. Current @@SESSION.GTID_NEXT is 'xyz'.
When mysqlbinlog processes a binary log containing GTIDs, it outputs SET gtid_next statements,
but gtid_next is set to undefined whenever a commit occurs; this left gtid_next undefined when the
server had finished processing the output from mysqlbinlog. When the next binary log file started with
one or more anonymous statements or transactions, the combination of gtid_next being left undefined at
the end of the first binary log and the second binary log containing anonymous transactions to the error
described previously (Error 1837, ER_GTID_NEXT_TYPE_UNDEFINED_GROUP).
To fix this issue, now, whenever mysqlbinlog encounters this situation, it inserts SET gtid_next =
AUTOMATIC if required to avoid leaving the previous binary log with gtid_next undefined.
In addition, as a result of this fix, mysqlbinlog no longer outputs session variable information for every
binary log; now, this value is printed only once unless it changes. (Bug #18258933, Bug #71695)
• Replication: When the I/O thread reconnected to a master using GTIDs and multithreaded slaves while
in the middle of a transaction, it failed to abort the transaction, leaving a partial transaction in the relay
log, and then retrieving the same transaction again. This occurred when performing a rotation of the
relay log. Now when reconnecting, the server checks before rotating the log in such cases, and waits
first for any ongoing transaction to complete. (Bug #17326020)
• Replication: The CLIENT_REMEMBER_OPTIONS flag for compressed slave connections is no longer
reset and all options are retained. This restores functionality of all options to compressed slave
connections. (Bug #72901, Bug #18923691, Bug #73324, Bug #19244772)
• Replication: When using row-based replication, setting a slave's slave_rows_search_algorithms
variable to HASH_SCAN caused an ER_KEY_NOT_FOUND error even though that record existed in the
storage layer. This fix ensures that the unique key for each record is correctly maintained and such a
situation does not occur. (Bug #72788, Bug #18860225)
• Replication: When using row-based replication, running a long transaction involving a large number
of events could trigger an Out of Memory (OOM) error if the slave's table structure was not compatible
with the master's table structure. Such an incompatible situation could occur if the table on the slave had
been manually changed, or when replicating between different MySQL versions that have different data
types. This OOM error was caused because the virtual temporary tables created for the row conversion
were not being freed until the end of the transaction, which was a problem when replicating large
numbers of events.
56
MySQL 5.6 Release Notes
Starting with this version, such virtual tables are correctly freed during the conversion process. (Bug
#72610, Bug #18770469)
References: See also: Bug #19692387.
• Replication: The error messages generated when a duplicate server UUID causes issues during
replication have been improved. The slave error now identifies the duplicate server UUID and the master
error identifies the zombie thread that has been killed. (Bug #72578, Bug #18731211)
• Replication: When an event group was spanned across multiple relay log files, a slave could incorrectly
identify GTID-header group boundaries. This meant that when a transaction was retried, or if the SQL
thread was stopped in the middle of a transaction after some rotates, the Gtid_log_event was being
silently skipped on the slave, and the transaction was logged with the slave's GTID. This problem also
impacted on using START SLAVE UNTIL MASTER_LOG_POS = log_pos; with GTIDs enabled.
If log_pos was in the middle of a transaction, the Gtid_log_event was not correctly detected
as the beginning of the transaction and replication stopped before this event. With this fix, threads
correctly detect that they are part of a group, and this is used to check if a Gtid_log_event is part of a
transaction. (Bug #72313, Bug #18652178, Bug #18306199)
• Replication: On a master that is using semisynchronous replication, where
rpl_semi_sync_master_wait_no_slave is enabled and rpl_semi_sync_master_timeout is
set to long timeout, killing the I/O thread could cause the server to hang on shutdown. This fix ensures
that if the dump thread finds that there no semisynchronous slaves connected to the master, the setting
of rpl_semi_sync_master_wait_no_slave is ignored and the shutdown proceeds correctly. (Bug
#71047, Bug #17879675)
• Replication: When using semisynchronous replication, if the binary log position was changed to a future
position on a slave then an assertion error was generated on the master. This fix ensures that in such
a situation the future position is correctly acknowledged and an error is instead generated on the slave.
(Bug #70327, Bug #17453826)
• Replication: When an SQL thread which was waiting for a commit lock was killed and restarted
it caused a transaction to be skipped on slave. This fix ensures that thread positions are correctly
persisted and transactions resume at the correct position. (Bug #69873, Bug #17450876)
• With DTrace support enabled, certain other compilation options could cause the build to fail. (Bug
#19506247)
• yaSSL client code did not validate the encryption size or session ID length, which could cause the client
to exit. (Bug #19463277, Bug #19463565)
• yaSSL could fail preauthorization if the client supplied inaccurate buffer lengths. (Bug #19370676, Bug
#19355577)
• Competition between threads could lead to timeout failure trying to rotate the audit log file. (Bug
#19184973)
• LPAD() and RPAD() could cause a server exit if the pad string argument was not well formed. (Bug
#18935421)
• The optimizer could create a zero-length column for a temporary table, causing a server exit. (Bug
#18928848)
• MOD for very small decimal right-hand arguments could cause a server exit. (Bug #18469276)
• The client library now includes a call to X509_verify_cert_error_string() in the SSL certificate
verification code, to be more robust in detecting invalid certificates. (Bug #18384260)
57
MySQL 5.6 Release Notes
• If the left-hand-side of an IN predicate was a scalar subquery but returned no row, the server could exit.
(Bug #18223655, Bug #18447874)
• The thread_concurrency system variable is deprecated, but no warning resulted from setting it at
server startup. (Bug #17873011)
• Sending a SIGQUIT or SIGINT signal to mysql could result in a glibc double free or corruption error.
(Bug #17297324)
• RPM Bundle tar file distributions did not include the shared compatibility library RPM. (Bug #74611,
Bug #19909411)
• On EL7, installation of MySQL from RPM packages could fail if postfix had previously been installed
using yum. (Bug #73507, Bug #19392051, Bug #19392149)
• The query cache was not invalidated for a table when a CASCADE DELETE or CASCADE UPDATE
referential constraint was specified and the database name or table name contained special characters.
(Bug #72547, Bug #18710853)
• mysql_upgrade could fail if the mysql.user table contained multiple accounts with the same user
name and host name where the host name differed in lettercase. This is still not permitted, but now
mysql_upgrade prints a more informative error message to indicate the nature of the problem:
ERROR 1644 (45000): Multiple accounts exist for user_name, host_name
that differ only in Host lettercase; remove all except one of them
(Bug #72066, Bug #18415196)
• A simultaneous OPTIMIZE TABLE and online ALTER TABLE on the same InnoDB table could result in
deadlock. (Bug #71433, Bug #18110156)
• Invalid memory access could occur when using prepared statements if a mysql client connection was
lost after statement preparation was complete and there was at least one statement that was in initialized
state but not prepared yet. (Bug #70429, Bug #17512527)
• If the general query log or slow query log file was set to a FIFO or socket file, and the file reader
went away, the server stopped executing statements. Now the server detects such files, logs an error
message, and continues with the appropriate log disabled. (Bug #67088, Bug #14757009)
• LIKE matches failed for code points of HALF WIDTH KATAKANA in the sjis and cp932 character
sets. (Bug #47641, Bug #11755818)
Changes in MySQL 5.6.20 (2014-07-31, General Availability)
• DTrace Support
• InnoDB Notes
• MySQL Enterprise Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
DTrace Support
58
MySQL 5.6 Release Notes
• MySQL now includes DTrace support on Oracle Linux 6 or higher with UEK kernel. If DTrace is present,
server builds will detect it with no special CMake options required. For information about using DTrace on
MySQL, see Tracing mysqld Using DTrace.
InnoDB Notes
• Important Change: Redo log writes for large, externally stored BLOB fields could overwrite the most
recent checkpoint. The 5.6.20 patch limits the size of redo log BLOB writes to 10% of the redo log file
size. The 5.7.5 patch addresses the bug without imposing a limitation. For MySQL 5.5, the bug remains
a known limitation.
As a result of the redo log BLOB write limit introduced for MySQL 5.6, the innodb_log_file_size
setting should be 10 times larger than the largest BLOB data size found in the rows of your tables plus
the length of other variable length fields (VARCHAR, VARBINARY, and TEXT type fields). No action is
required if your innodb_log_file_size setting is already sufficiently large or your tables contain no
BLOB data.
Note
In MySQL 5.6.22, the redo log BLOB write limit is relaxed to 10% of the total redo
log size (innodb_log_file_size * innodb_log_files_in_group).
(Bug #16963396, Bug #19030353, Bug #69477)
MySQL Enterprise Notes
• The audit log plugin included in MySQL Enterprise Edition now has the capability of filtering audited
events based on user account and event status. Several new system variables provide DBAs with
filtering control. In addition, audit log plugin reporting capability has been improved by the addition of
several status variables.
Incompatible configuration change: audit_log_policy can be set at server startup (as before), but
at runtime is now a read-only variable. This is due to the introduction of two new system variables,
audit_log_connection_policy and audit_log_statement_policy, that provide finer
control over logging policy and that can be set either at startup or at runtime. If you continue to use
audit_log_policy at startup instead of the other two variables, the server uses its value to set those
variables.
For more information, see Audit Log Logging Control, and Audit Log Plugin Status Variables.
Security Notes
• Security Fix: The linked OpenSSL library for the MySQL 5.6 Commercial Server has been updated from
version 1.0.1g to version 1.0.1h. Versions of OpenSSL prior to and including 1.0.1g are reported to be
vulnerable to CVE-2014-0224.
This change does not affect the Oracle-produced MySQL Community build of MySQL Server 5.6, which
uses the yaSSL library instead. (Bug #18917858, CVE-2014-0224)
Functionality Added or Changed
• Replication: The new system variable binlogging_impossible_mode controls what happens if the
server cannot write to the binary log, for example, due to a file error. For backward compatibility, the
default for binlogging_impossible_mode is IGNORE_ERROR, meaning the server logs the error,
halts logging, and continues updates to the database. Setting this variable to ABORT_SERVER makes the
server halt logging and shut down if it cannot write to the binary log. (Bug #51014, Bug #11758766)
59
MySQL 5.6 Release Notes
• New Debian7, Ubuntu12.04, and Ubuntu14.04 distribution support that was introduced with 5.6.17 now
comes with the platform-specific packaging source placed under the packaging directory, in the debprecise, deb-wheezy, and deb-trusty directories. (Bug #19020385)
• CMake support was updated to handle CMake version 3. (Bug #19001781)
• The timed_mutexes system variable has no effect and is deprecated. (Bug #18277305)
• Support for LinuxThreads has been removed from the source code. LinuxThreads was superseded by
NPTL in Linux 2.6. (Bug #17007529, Bug #72888, Bug #18913935)
• By default, mysql_install_db creates a my.cnf file in the installation base directory using a
template. This may be undesireable for some deployments. To enable this behavior to be suppressed,
mysql_install_db now supports a --keep-my-cnf option to preserve any existing my.cnf file and
not create a new my.cnf file. (Bug #71600, Bug #18205019)
• The mysqlhotcopy utility is now deprecated and will be removed in a future version of MySQL. Among
the reasons for this: It works only for the MyISAM and ARCHIVE storage engines; it works on Unix but not
Windows. Alternatives include mysqldump and MySQL Enterprise Backup.
Bugs Fixed
• Important Change; Replication: A DROP TABLE statement may be divided into multiple statements
before it is sent to the binary log if it contains regular (not temporary) tables and temporary tables, or
if it contains temporary tables using both transactional and non-transactional storage engines. Now,
when using GTIDs, DROP TABLE statements affecting these combinations of tables are no longer
allowed unless the value of the gtid_next system variable is AUTOMATIC. This is because, with GTIDs
enabled on the server, issuing a DROP TABLE in the cases just described while having only one GTID
associated with each statement (the SQL thread does this following SET gtid_next='uuid:number')
causes problems when there are not enough GTIDs for assignment to all the resulting statements
following the division of the original DROP TABLE.
A DROP TABLE statement might be split due to the behavior of the statement with respect to the current
transaction varying, depending on table characteristics, as follows:
• DROP TABLE of a regular (not temporary) table is committed immediately
• DROP TABLE of a temporary table using a transactional storage engine is committed with the current
transaction (following COMMIT)
• DROP TABLE of a temporary table that uses a nontransactional storage engine is committed
immediately
Naming all three of these types of tables in a single DROP TABLE statement causes the MySQL server
to divide the original statement into three separate DROP TABLE statements in the binary log. If GTIDs
are enabled but the value of gtid_next is not AUTOMATIC, issuing a DROP TABLE statement that
mixes any of the table types described previously causes the server to have an insufficient number
of GTIDs to write with all of the resulting statements into the binary log. In addition, DROP TABLE IF
EXISTS is always written in the binary log for all tables specified in the statement, even if some or all of
the tables do not exist.
Because temporary tables are handled differently by DROP TABLE depending on whether they use a
transactional or nontransactional storage engine, any tables named by a DROP TEMPORARY TABLE
statement that do not exist are assumed to be transactional. This means that, if a DROP TEMPORARY
TABLE with two nontransactional temporary tables is issued on the master, it would writes only one
DROP TABLE statement naming both tables. If one of the temporary tables no longer exists on the slave,
then, when the SQL thread executes the statement, it tries to divide it into multiple statements due to
60
MySQL 5.6 Release Notes
it affecting a nontransactional (but existing) temporary table and a nonexistent transactional temporary
table; this leads to problems because the SQL thread has only one GTID for the original DROP TABLE
statement but must write two DROP TABLE statements in the binary log.
In addition, when the slave dropped temporary tables after detecting that the master had restarted, it
logged one DROP TABLE statement per pseudo-thread and per database, but combined temporary
tables using transactional and nontransactional storage engines in a single DROP TABLE statement.
Now, we throw an error in the client session if gtid_next is set to a uuid:number value and a DROP
TABLE statement is issued mixing any of the table types described previously.
In addition, we now group the nonexistent temporary tables and assume them to be transactional only
if at least one transactional temporary table is dropped by the statement. If no transactional temporary
tables are dropped, any nonexistent temporary tables are assumed to be nontransactional temporary
tables.
The slave now also handles dropping of temporary tables correctly in the event of the restart by the
master. (Bug #17620053)
• InnoDB: Opening a parent table that has thousands of child tables could result in a long semaphore wait
condition. (Bug #18806829)
• InnoDB: On mysqld start, specifying multiple data files using the innodb_data_file_path
option would return a Space id in fsp header error after data is written to the second file. (Bug
#18767811)
• InnoDB: For single item full-text searches, deleted documents were included in inverse document
frequency (IDF) calculations. (Bug #18711306, Bug #72548)
• InnoDB: A DELETE operation on a table with full-text search indexes raised an assertion. (Bug
#18683832)
References: See also: Bug #14639605.
• InnoDB: When InnoDB is built as a shared library, attempting to load the InnoDB full-text search (FTS)
INFORMATION_SCHEMA plugin would fail with a Can't open shared library 'ha_innodb.so'
error. (Bug #18655281, Bug #70178)
• InnoDB: When calling the memcached flush_all command, InnoDB attempts to initialize a
connection and a transaction. If the transaction is in TRX_STATE_NOT_STARTED state, InnoDB failed to
set CONN_DATA->CRSR_TRX to NULL, resulting in a serious error. (Bug #18652854)
• InnoDB: A regression introduced in MySQL 5.6.5 would cause full-text search index tables to be created
in the system tablespace (space 0) even though innodb_file_per_table was enabled. (Bug
#18635485)
• InnoDB: The InnoDB memcached plugin would call plugin_del without acquiring the lock_plugin
mutex. This bug fix also addresses a race condition in ib_cursor_delete_row. (Bug #18409840)
• InnoDB: The fix for Bug#16418661 added superfluous buf_flush_list() logic to InnoDB startup
code. (Bug #17798076, Bug #70899)
References: This issue is a regression of: Bug #16418661.
• InnoDB: A race condition in fts_get_next_doc_id resulted in Duplicate FTS_DOC_ID and
Cannot find index FTS_DOC_ID_INDEX in InnoDB index translation table errors. (Bug
#17447086, Bug #70311)
61
MySQL 5.6 Release Notes
References: See also: Bug #16469399.
• InnoDB: Due to differences in memory ordering on different processor types, some mutex and readwrite lock flags were not read consistently. (Bug #11755438, Bug #47213)
• Partitioning: Selecting from a table having multiple columns in its primary key and partitioned by LIST
COLUMNS(R), where R was the last (rightmost) column listed in the primary key definition, returned an
incorrect result. (Bug #17909699, Bug #71095)
• Replication: mysqlbinlog --raw did not check for errors caused by failed writes, which could result in
silent corruption of binary logs. Now in such cases it stops with an error. (Bug #18742916, Bug #72597)
• Replication: When a slave worker thread tried to execute a statement that was too large, the resulting
error caused a crash. Now in such cases, the error is truncated to fit the size of the buffer. (Bug
#18563480)
• Replication: When using row-based replication, updating or deleting a row on the master that did not
exist on the slave led to failure of the slave when it tried to process the change. This problem occurred
with InnoDB tables lacking a primary key. (Bug #18432495, Bug #72085)
• Replication: Quotation marks were not always handled correctly by LOAD DATA INFILE when written
into the binary log. (Bug #18207212, Bug #71603)
• Replication: Beginning in MySQL 5.6.20, when a user specified AUTO_INCREMENT value falls outside
of the range between the current AUTO_INCREMENT value and the sum of the current and number of
rows affected values it is replicated correctly. In previous versions, an error was generated by the slave
even if the user specified AUTO_INCREMENT value fell outside of the range. (Bug #17588419, Bug
#70583)
• Replication: On Windows, mysqldump failed if the error log file was deleted (missing) from the active
MySQL server. (Bug #17076131)
• Replication: Client applications should be able to set the BINLOG_DUMP_NON_BLOCK flag in the initial
handshake packet (COM_BINLOG_DUMP). Clients connecting to a server issuing a COM_BINLOG_DUMP
with the flag unset do not get an EOF when the server has sent the last event in the binary log, which
causes the connection to block. This flag, which was removed in error in MySQL 5.6.5, is now restored in
the current release.
As part of this fix, a new --connection-server-id option is added to mysqlbinlog. This option
can be used by the client to test a MySQL server for the presence of this issue. (Bug #71178, Bug
#18000079)
• Replication: Uninstalling and reinstalling semisynchronous replication plugins while semisynchronous
replication was active caused replication failures. The plugins now check whether they can be
uninstalled and produce an error if semisynchronous replication is active. To uninstall the master-side
plugin, there must be no semisynchronous slaves. To uninstall the slave-side plugin, there must be no
semisynchronous I/O threads running. (Bug #70391, Bug #17638477)
• Replication: Replication of tables that contained temporal type fields (such as TIMESTAMP, DATETIME,
and TIME) from different MySQL versions failed due to incompatible TIMESTAMP types. The fractional
TIMESTAMP format added in MySQL 5.6.4 was not being correctly converted. You can now replicate
a TIMESTAMP in either format correctly according to the slave_type_conversions variable. (Bug
#70124, Bug #17532932)
• Replication: A group of threads involved in acquiring locks could deadlock when the following events
occurred:
62
MySQL 5.6 Release Notes
1. Dump thread reconnects from slave; on master, a new dump thread tries to kill zombie dump
threads; having acquired the thread's LOCK_thd_data, it is about to acquire LOCK_log.
2. Application thread executing show binary logs, having acquired LOCK_log and about to acquire
LOCK_index.
3. Application thread executing PURGE BINARY LOGS; having acquired LOCK_index, it is about to
acquire LOCK_thread_count.
4. Application thread executing SHOW PROCESSLIST (or SELECT * FROM
INFORMATION_SCHEMA.PROCESSLIST), having acquired LOCK_thread_count and about to
acquire the zombie dump thread's LOCK_thd_data.
This leads to the 4 threads deadlocking in the same order which the threads have been listed here.
This problem arises because there are ordering rules for LOCK_log and LOCK_index, as well as rules
for ordering LOCK_thread_count and LOCK_thd_data, but there are no rules for ordering across
these two sets of locks. This was because the internal mysqld_list_processes() function invoked
by SHOW PROCESSLIST acquired LOCK_thread_count for the complete lifetime of the function as
well as acquiring and releasing each thread's LOCK_thd_data. Now this function takes a copy of
the threads from the global thread list and performs its traversal on these, and only after releasing
LOCK_thread_count. During this traversal, removal from the global thread list is blocked using
LOCK_thd_remove such that the copies that would otherwise be destroyed by the removal remain valid
during traversal. The locking order following this fix is shown here:
LOCK_thd_remove -> LOCK_thd_data -> LOCK_log -> LOCK_index -> LOCK_thread_count
(Bug #69954, Bug #17283409)
References: See also: Bug #73475, Bug #19364731, Bug #19365180.
• When a SELECT included a derived table in a join in its FROM list and the SELECT list included
COUNT(DISTINCT), the COUNT() returned 1 even if the underlying result set was empty. (Bug
#18853696)
References: This issue is a regression of: Bug #11760197.
• Enabling optimizer trace could cause a server exit for queries with a subquery in a HAVING clause. (Bug
#18791851)
• SHA and MD5 functions failed for operations using the internal filename character set and could cause
a server exit. (Bug #18786138)
• Large arguments passed to mysqldump could lead to buffer overflow and program exit. (Bug
#18779944)
• After a metadata change, a reprepared trigger could cause a server exit or prune an incorrect partition.
(Bug #18684393)
• ALTER TABLE on a partitioned table could result in the wrong storage engine being written into the
table's .frm file and displayed in SHOW CREATE TABLE. (Bug #18618561)
• Compiler flags were not passed to DTrace, causing problems for 32-bit builds cross-compiled on 64-bit
platforms. (Bug #18593044)
63
MySQL 5.6 Release Notes
• With the max_heap_table_size system variable set to a large value (20GB), creation of a temporary
table or a table using the MEMORY storage engine caused a server exit. (Bug #18463911)
• If MySQL was built with the -DINSTALL_LIBDIR=lib64 option, mysql_config did not work if the
MySQL package was unpacked into a location with a different installation prefix. Also, mysql_config
did not work for some RPM builds because it used an incorrect installation prefix. (Bug #18382225)
• For debug builds, a 0x00 character in a full-text query string that used the ujis_japanese_ci,
utf8mb4_turkish_ci, or eucjpms_bin collation could raise an assertion. (Bug #18277305)
• yaSSL code had an off-by-one error in certificate decoding that could cause buffer overflow.
yaSSL code had an opendir() without a corresponding closedir(). (Bug #18178997, Bug
#17201924)
• mysqladmin password masked the old password given on the command line, but not the new
password. (Bug #18163964)
• For full-text queries on InnoDB tables, attempts to access deleted document IDs could lead to a server
exit. (Bug #18079671)
• MyISAM temporary files could be used to mount a code-execution attack. (Bug #18045646)
• For queries that selected from the events_statements_current Performance Schema table, adding
an ORDER BY clause could produce incorrect results. (Bug #17729044)
• If a query had both MIN()/MAX() and aggregate_function(DISTINCT) (for example,
SUM(DISTINCT)) and was executed using Loose Index Scan, the result values of MIN()/MAX() were
set improperly. (Bug #17217128)
• For UNION statements, the rows-examined value was calculated incorrectly. This was manifest as
too-large values for the ROWS_EXAMINED column of Performance Schema statement tables (such as
events_statements_current). (Bug #17059925)
• Clients could determine based on connection error message content whether an account existed. (Bug
#16513435, Bug #17357528, Bug #19273967)
• An assertion could be raised when creating a index on a prefix of a TINYBLOB or GEOMETRY column in
an InnoDB column. (Bug #16368875, Bug #18776592, Bug #17665767)
• Use of a nonmultibyte algorithm for skipping leading spaces in multibyte strings could cause a server
exit. (Bug #12368495, Bug #18315770)
• Binary MySQL distributions for OS X 10.8 and up now bundle the MySQL.prefPane and
MySQLStartupItem.pkg tools into the main package as configurable options instead of separate
packages. (Bug #74123, Bug #19701502)
• A new CMake option, SUNPRO_CXX_LIBRARY, enables linking against libCstd instead of stlport4
on Solaris 10 or later. This works only for client code because the server depends on C++98. Example
usage:
cmake -DWITHOUT_SERVER=1 -DSUNPRO_CXX_LIBRARY=Cstd
(Bug #72352, Bug #18605389)
• mysql_config_editor exited when given an empty argument to the --login-path option. (Bug
#71837, Bug #18311024, Bug #18830493)
64
MySQL 5.6 Release Notes
• Upgrades using RPM packages could change the ownership of an installation directory. (Bug #71715,
Bug #18281535)
• Proxy users were unable to execute statements if the proxied user password had expired. (Bug #71337,
Bug #18057562)
• MySQL did not compile with Bison 3. (Bug #71250, Bug #18017820, Bug #18978946)
• Deadlock could occur if three threads simultaneously performed INSTALL PLUGIN, SHOW VARIABLES,
and mysql_change_user(). (Bug #71236, Bug #18008907, Bug #72870, Bug #18903155)
• If there was a predicate on a column referenced by MIN() or MAX() and that predicate was not present
in all the disjunctions on key parts earlier in the compound index, Loose Index Scan returned an
incorrect result. (Bug #71097, Bug #17909656)
• Client auto-reconnect did not work for clients linked against libmysqlclient, even with
MYSQL_OPT_RECONNECT enabled.
Also, if a FEDERATED table was accessed after wait_timeout expired, a Lost connection to
MySQL server error occurred without an attempt to re-establish the connection. (Bug #70026, Bug
#17309863, Bug #14874, Bug #11745408)
• File permissions and line endings of several test and configuration files were made more consistent to
avoid warnings from package checkers. (Bug #68521, Bug #16415173, Bug #16395459, Bug #68517,
Bug #16415032, Bug #71112, Bug #17919313, Bug #71113, Bug #17919422)
• Configuring with cmake -DWITHOUT_SERVER to build clients without the server failed for builds outside
of the source tree. (Bug #66000, Bug #14367046)
• For a view defined on a UNION, the server could create an invalid view definition. (Bug #65388, Bug
#14117018, Bug #72018, Bug #18405221)
• With big_tables enabled, queries that used COUNT(DISTINCT) on a simple join with a constant
equality condition on a non-duplicate key returned incorrect results. (Bug #52582, Bug #11760197)
References: See also: Bug #18853696.
Changes in MySQL 5.6.19 (2014-05-30, General Availability)
There is no MySQL Community Server 5.6.18. That version number was used for an out-of-schedule
release of MySQL Enterprise Edition to address the OpenSSL “Heartbleed” issue. This issue did not affect
MySQL Community Edition because it uses yaSSL, not OpenSSL, so a new release of the Community
Server was not needed, and 5.6.17 is followed by 5.6.19.
• Functionality Added or Changed
• Bugs Fixed
Functionality Added or Changed
• The obsolete and unmaintained charset2html utility has been removed from MySQL distributions.
(Bug #71897, Bug #18352347)
• The mysqlbug, mysql_waitpid, and mysql_zap utilities have been deprecated and will be removed
in MySQL 5.7.
Bugs Fixed
65
MySQL 5.6 Release Notes
• InnoDB: After upgrading from 5.6.10 to MySQL versions up to and including MySQL 5.6.18, InnoDB
would attempt to rename obsolete full-text search auxiliary tables on server startup, resulting in an
assertion failure. (Bug #18634201, Bug #72079)
• InnoDB: With persistent statistics enabled, SHOW TABLE STATUS output and the TABLE_ROWS column
of INFORMATION_SCHEMA.TABLES could report an incorrect number of table rows for tables with
externally stored pages. (Bug #18384390)
• InnoDB: The fix for Bug#17699331 caused a high rate of read/write lock creation and destruction which
resulted in a performance regression. (Bug #18345645, Bug #71708)
References: This issue is a regression of: Bug #17699331.
• InnoDB: For each insert, memset would be called three times to allocate memory for system fields. To
reduce CPU usage, the three memset calls are now combined into a single call. (Bug #17858679, Bug
#71014)
• InnoDB: Enabling the InnoDB Table Monitor would result in a ib_table->stat_initialized
assertion failure. (Bug #17039528, Bug #69641)
• InnoDB: With innodb_max_dirty_pages_pct=0 buffer pool flushing would not be initiated until the
percentage of dirty pages reached at least 1%, which would leave up to 1% of dirty pages unflushed.
(Bug #13029450, Bug #62534)
• Replication: Log rotation events could cause group_relay_log_pos to be moved forward incorrectly
within a group. This meant that, when the transaction was retried, or if the SQL thread was stopped
in the middle of a transaction following one or more log rotations (such that the transaction or group
spanned multiple relay log files), part or all of the group was silently skipped.
This issue has been addressed by correcting a problem in the logic used to avoid touching the
coordinates of the SQL thread when updating the log position as part of a relay log rotation whereby it
was possible to update the SQL thread's coordinates when not using a multi-threaded slave, even in the
middle of a group. (Bug #18482854)
• Replication: When running the server with --gtid-mode=ON, STOP SLAVE followed
by START SLAVE resulted in a mismatch between the information provided by
INFORMATION_SCHEMA.INNODB_TEMP_TABLE_INFO and the Slave_open_temp_tables
status variable: the INNODB_TEMP_TABLE_INFO table showed that no temporary tables existed, but
Slave_open_temp_tables had a nonzero value. (Bug #18364070)
References: See also: Bug #18236612.
• Replication: In certain cases, the server mishandled triggers and stored procedures that tried to modify
other tables when called by CREATE TABLE ... SELECT. This is now handled correctly as an error.
(Bug #18137535)
• Replication: When used on a table employing a transactional storage engine, a failed TRUNCATE
TABLE was still written to the binary log and thus replayed on the slave. This could lead to inconsistency
when the master retained data that was removed on the slave.
Now in such cases TRUNCATE TABLE is logged only when it executes successfully. (Bug #17942050,
Bug #71070)
• Replication: The server did not always handle the auto.cnf file correctly in cases where this file's
permissions were incorrect. (Bug #17786581, Bug #70891)
• Replication: When the binary log was rotated due to receipt of a SIGHUP signal, the new binary log
did not contain the Previous_gtid_event required for subsequent processing of that binary log's
66
MySQL 5.6 Release Notes
GTID events. Now when SIGHUP is received, steps are taken to insure that the server writes the
necessary Previous_gtid_event to the new log before writing any GTID events to the new log. (Bug
#17026898)
• Replication: When gtid_mode=ON, and a transaction is filtered out on the slave, the GTID of the
transaction is still logged on the slave as an “empty” transaction (consisting of a GTID followed
immediately by BEGIN and then COMMIT). This is necessary to prevent the transaction from being
retransmitted the next time the slave reconnects or is involved in a failover. The current fix addresses
two issues relating to such “empty” transactions:
• No empty transaction was generated for CREATE TEMPORARY TABLE or DROP TEMPORARY TABLE
statements.
• If the slave used a database filter (--replicate-do-db or --replicate-ignore-db option), no
empty transaction was generated.
(Bug #71376, Bug #18095502, Bug #18145032)
• The server could fail to properly reprepare triggers that referred to another table after that table was
truncated. (Bug #18596756, Bug #72446, Bug #18665853)
• For indexes on prefixes or character string columns, index corruption could occur for assignment of
binary data to the column due to improper character counting. (Bug #18359924)
• Certain INFORMATION_SCHEMA queries could cause a server exit. (Bug #18319790)
• Solaris-specific scripts were included in and installed by non-Solaris packages. (Bug #18305641)
• innobase_strnxfrm() wrote one byte too many. (Bug #18277082)
• EXPLAIN on a query with an EXISTS subquery containing a UNION could cause a server exit.
Multiple executions of a prepared EXPLAIN on a UNION of subqueries could cause a server exit. (Bug
#18167356)
• Concurrent execution of a FLUSH TABLES operation and a stored program that used a cursor could
cause a server exit. (Bug #18158639)
• The client library could cause clients to exit due to incorrectly mapping the client error number to the
corresponding message, if reallocation of packet buffer memory occurred. (Bug #18080920)
• Calling mysql_get_server_version() with an invalid connection handler argument caused the
client to exit. Now it returns 0 and reports a CR_COMMANDS_OUT_OF_SYNC error. (Bug #18053212)
• On Windows, calling mysql_thread_init() call without mysql_init() caused the client to exit.
windows. Now it returns a nonzero result because it is an error to call mysql_thread_init() before
the client library is initialized with mysql_library_init(). (Bug #17514920)
• mysqldump could create table definitions in the dump file that resulted in Too many columns errors
when reloading the dump file. (Bug #17477959)
• The optimizer trace could cause a server exit in cases where a subquery was transformed away. (Bug
#17458054)
• The Debug Sync facility could lose a signal, leading to a spurious ER_DEBUG_SYNC_TIMEOUT error.
(Bug #14765080, Bug #18221750)
• A statement of the following form broke row-based replication because it created a table having a field of
data type BIGINT with a display width of 3000, which is beyond the maximum acceptable value of 255:
67
MySQL 5.6 Release Notes
CREATE TABLE t1 AS SELECT REPEAT('A',1000) DIV 1 AS a;
(Bug #71179, Bug #17994219)
• CMake produced not-useful warnings about INTERFACE_LINK_LIBRARIES policy. (Bug #71089, Bug
#17905155, Bug #17894997)
• Updates could fail to update all applicable rows in cases where multiple key values were identical except
for trailing spaces. (Bug #69684, Bug #17156940)
• On Windows, REPAIR TABLE and OPTIMIZE TABLE failed for MyISAM tables with .MYD files larger
than 4GB. (Bug #69683, Bug #17235179)
• Compilation problems were fixed for errors reported by Clang and gcc when compiling in C++11 mode.
(Bug #66803, Bug #14631159)
• LOAD DATA LOCAL INFILE could use all CPU if import errors occurred when there were no line
delimiters. (Bug #51840, Bug #11759519)
Changes in MySQL 5.6.18 (2014-04-11, General Availability)
A known limitation of this release:
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Heartbleed Bug
• Bugs Fixed
Heartbleed Bug
• Security Fix: The MySQL 5.6 Commercial Server has been updated to use OpenSSL version 1.0.1g,
which has been publicly reported as not vulnerable to CVE-2014-0160. Please see Oracle Note
#1645479.1 for further details.
The MySQL 5.6 Community Server is built using the yaSSL cryptographic software library instead of
OpenSSL. Oracle-produced MySQL 5.6 Community Server binaries use YaSSL libraries which have
been reported as not affected by CVE-2014-0160. Users of MySQL Server binaries produced by parties
other than Oracle should seek a vulnerability assessment from their respective binary providers.
Since the only change in MySQL Server 5.6.18 is the inclusion of OpenSSL libraries publicly reported
as unaffected by CVE-2014-0160, and since Oracle-produced MySQL Community builds do not include
OpenSSL libraries known to be affected by CVE-2014-0160, Oracle is not producing builds for MySQL
Community Server for version 5.6.18. This means that MySQL Community Server is skipping version
5.6.18. (Bug #18533200, CVE-2014-0160)
Bugs Fixed
68
MySQL 5.6 Release Notes
• Executing a correlated subquery on an ARCHIVE table which has an AUTO_INCREMENT column caused
the server to hang. (Bug #18065452)
Changes in MySQL 5.6.17 (2014-03-27, General Availability)
A known limitation of this release:
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Deprecation and Removal Notes
• Functionality Added or Changed
• Bugs Fixed
Deprecation and Removal Notes
• Incompatible Change: The ERROR_FOR_DIVISION_BY_ZERO, NO_ZERO_DATE, and
NO_ZERO_IN_DATE SQL modes now are deprecated and setting the sql_mode value to include any of
them generates a warning. In MySQL 5.7, these modes do nothing. Instead, their effects are included
in the effects of strict SQL mode (STRICT_ALL_TABLES or STRICT_TRANS_TABLES). The motivation
for the change in MySQL 5.7 is to reduce the number of SQL modes with an effect dependent on strict
mode and make them part of strict mode itself.
To make advance preparation for an upgrade to MySQL 5.7, see SQL Mode Changes in MySQL 5.7.
That discussion provides guidelines to assess whether your applications will be affected by the SQL
mode changes in MySQL 5.7.
• The msql2mysql, mysql_convert_table_format, mysql_find_rows,
mysql_fix_extensions, mysql_setpermission, and mysqlaccess utilities are now deprecated
and will be removed in MySQL 5.7. (Bug #27482, Bug #69012, Bug #69014, Bug #69015, Bug #69016,
Bug #69017, Bug #11746603, Bug #16699248, Bug #16699279, Bug #16699284, Bug #16699317, Bug
#18179576)
• The IGNORE clause for ALTER TABLE is now deprecated and will be removed in a future version of
MySQL. ALTER IGNORE TABLE causes problems for replication, prevents online ALTER TABLE for
unique index creation, and causes problems with foreign keys (rows removed in the parent table).
Functionality Added or Changed
• Incompatible Change: The AES_ENCRYPT() and AES_DECRYPT() functions now permit control of the
block encryption mode and take an optional initialization vector argument:
• The new block_encryption_mode system variable controls the mode for block-based encryption
algorithms. Its default value is aes-128-ecb, which signifies encryption using a key length of 128 bits
and ECB mode.
• An optional init_vector argument provides an initialization vector for encryption modes that require
it:
69
MySQL 5.6 Release Notes
AES_ENCRYPT(str,key_str[,init_vector])
AES_DECRYPT(crypt_str,key_str[,init_vector])
• A random string of bytes to use for the initialization vector can be produced by calling the new
RANDOM_BYTES() function.
For more information, see Encryption and Compression Functions.
These changes make statements that use AES_ENCRYPT() or AES_DECRYPT() unsafe for statementbased replication and they cannot be stored in the query cache. Queries that use RANDOM_BYTES() are
unsafe for statement-based replication and cannot be stored in the query cache.
• InnoDB: Online DDL support is extended to the following operations for regular and partitioned InnoDB
tables:
• OPTIMIZE TABLE
• ALTER TABLE ... FORCE
• ALTER TABLE ... ENGINE=INNODB (when run on an InnoDB table)
Online DDL support reduces table rebuild time and permits concurrent DML. See Online DDL
Overview.
(Bug #13975225)
• Solaris: On Solaris, mysql_config --libs now includes -R/path/to/library so that libraries
can be found at runtime. (Bug #18235669)
• mysql_install_db provides a more informative diagnostic message when required Perl modules are
missing. (Bug #69844, Bug #18187451)
Bugs Fixed
• Incompatible Change: Old clients (older than MySQL 5.5.7) failed to parse authentication data correctly
if the server was started with the --default-authentication-plugin=sha256_password option.
Note
As a result of this bug fix, MySQL 5.6.16 clients cannot connect to a 5.6.17 server
using an account that authenticates with the sha256_password plugin, nor
can 5.6.17 clients connect to a 5.6.16 server. Similarly, MySQL 5.7.3 clients
cannot connect to a 5.7.4 server using an account that authenticates with the
sha256_password plugin.
(Bug #17495562)
• Important Change; InnoDB; Partitioning: The FLUSH TABLES statement's FOR EXPORT option is
now supported for partitioned InnoDB tables. (Bug #16943907)
• InnoDB: Running a SELECT on a partitioned table caused a memory access violation in memcpy().
(Bug #18383840)
References: See also: Bug #18167648.
• InnoDB: For full-text queries, a failure to check that num_token is less than max_proximity_item
could result in an assertion. (Bug #18233051)
70
MySQL 5.6 Release Notes
• InnoDB: An invalid memmove in fts_query_fetch_document would cause a serious error. (Bug
#18229433)
• InnoDB: innodb_ft_result_cache_limit now has a hardcoded maximum value of 4294967295
bytes or (2**32 -1). The maximum value was previously defined as the maximum value of ulong. (Bug
#18180057, Bug #71554)
• InnoDB: An UPDATE resulted in a memory access error in lock_rec_other_trx_holds_expl. The
transaction list (trx_sys->rw_trx_list) was traversed without acquiring the transaction subsystem
mutex (trx_sys->mutex). (Bug #18161853)
• InnoDB: InnoDB failed to restore a corrupt first page of a system tablespace data file from the
doublewrite buffer, resulting in a startup failure. (Bug #18144349, Bug #18058884)
• InnoDB: A regression introduced by Bug #14329288 would result in a performance degradation when a
compressed table does not fit into memory. (Bug #18124788, Bug #71436)
References: This issue is a regression of: Bug #14329288.
• InnoDB: The maximum value for innodb_thread_sleep_delay is now 1000000
microseconds. The previous maximum value (4294967295 microseconds on 32-bit and
18446744073709551615 microseconds on 64-bit) was unnecessarily large. Because
the maximum value of innodb_thread_sleep_delay is limited by the value set for
innodb_adaptive_max_sleep_delay (when set to a non-zero value), the maximum
value for innodb_thread_sleep_delay is now the same as the maximum value for
innodb_adaptive_max_sleep_delay. (Bug #18117322)
• InnoDB: Attempting to uninstall the InnoDB memcached plugin while the InnoDB memcached plugin is
still initializing would kill the InnoDB memcached daemon thread. Uninstall should wait until initialization
is complete. (Bug #18038948)
• InnoDB: A full-text tokenizer thread would terminate with an incorrect error message. (Bug #18021306)
• InnoDB: In debug builds, creating a unique index on a binary column, with input data containing
duplicate keys, would cause an assertion. (Bug #18010711)
• InnoDB: The srv_monitor_thread would crash in the lock_print_info_summary() function due
to a race condition between the srv_monitor_thread and purge coordinator thread. (Bug #17980590,
Bug #70430)
• InnoDB: Attempting to add an invalid foreign key when foreign key checking is disabled
(foreign_key_checks=0) would cause a serious error. (Bug #17666774)
• InnoDB: For debug builds, the table rebuilding variant of online ALTER TABLE, when run on tables with
BLOB columns, would cause an assertion in the row_log_table_apply_update function. For normal
builds, a DB_PRODUCTION error would be returned. (Bug #17661919)
• InnoDB: When creating a table there are a minimum of three separate inserts on the
mysql.innodb_index_stats table. To improve CREATE TABLE performance, there is now a single
COMMIT operation instead of one for each insert. (Bug #17323202, Bug #70063)
• InnoDB: The server would halt with an assertion in lock_rec_has_to_wait_in_queue(lock) due
to a locking-related issue and a transaction being prematurely removed from trx_sys->rw_trx_set.
(Bug #17320977)
• InnoDB: Server shutdown would result in a hang with the following message written to the error log:
“[NOTE] InnoDB: Waiting for purge thread to be suspended.” (Bug #16495065)
71
MySQL 5.6 Release Notes
• InnoDB: InnoDB failed to start when innodb_data_file_path specified the data file size in kilobytes
by appending K to the size value. (Bug #16287752)
• InnoDB: An insert buffer merge would cause an assertion error due to incorrectly handled ownership
information for externally stored BLOBs.
InnoDB: Assertion failure in thread thread_num in file ibuf0ibuf.cc line 4080
InnoDB: Failing assertion: rec_get_deleted_flag(rec, page_is_comp(page))
(Bug #14668683)
• InnoDB: Decreasing the auto_increment_increment value would have no affect on the next autoincrement value. (Bug #14049391, Bug #65225)
• Partitioning: When the index_merge_intersection flag (enabled by default) or the
index_merge_union flag was enabled by the setting of the optimizer_switch system variable,
queries returned incorrect results when executed against partitoned tables that used the MyISAM storage
engine, as well as partitioned InnoDB tables that lacked a primary key. (Bug #18167648)
References: See also: Bug #16862316, Bug #17588348, Bug #17648468.
• Replication: The MASTER_SSL_CRL and MASTER_SSL_CRLPATH options are not available when using
yaSSL; MySQL Replication now sets these to NULL automatically whenever yaSSL is enabled. (Bug
#18165937)
• Replication: Setting --slave-parallel-workers to 1 or greater and starting the slave caused the
slave SQL thread to use but not release memory until the slave was restarted with STOP SLAVE and
START SLAVE. (Bug #18001777, Bug #71197)
• Replication: When a slave was configured with replication filters and --log-warnings=2, every
statement which was filtered caused an entry to be written in the error log. For busy servers which
generated many statements to be filtered, the result was that the error log could quickly grow to many
gigabytes in size. Now a throttle is used for such errors, so that an error message is printed only once in
a given interval, saying that this particular error occurred a specific number of times during that interval.
(Bug #17986385)
• Replication: SHOW SLAVE STATUS used incorrect values when reporting MASTER_SSL_CRL and
MASTER_SSL_CRLPATH. (Bug #17772911, Bug #70866)
References: This issue is a regression of: Bug #11747191.
• Replication: Binary log events could be sent to slaves before they were flushed to disk on the master,
even when sync_binlog was set to 1. This could lead to either of those of the following two issues
when the master was restarted following a crash of the operating system:
• Replication cannot continue because one or more slaves are requesting replicate events that do not
exist on the master.
• Data exists on one or more slaves, but not on the master.
Such problems are expected on less durable settings (sync_binlog not equal to 1), but it should
not happen when sync_binlog is 1. To fix this issue, a lock (LOCK_log) is now held during
synchronization, and is released only after the binary events are actually written to disk. (Bug
#17632285, Bug #70669)
• Replication: When running the slave with --slave-parallel-workers at 1 or greater, setting -slave-skip-errors=all caused the error log to be filled with instances of the warning Slave SQL:
72
MySQL 5.6 Release Notes
Could not execute Query event. Detailed error: ;, Error_code: 0. (Bug #17581990,
Bug #68429)
References: See also: Bug #17986385.
• Replication: A number of possible state messages used as values for the PROCESSLIST_STATE
column of the threads Performance Schema table were longer than the width of the column (64
characters).
The long state messages are now silently truncated in order to avoid errors. This fix applies in MySQL
5.6 only; a permanent fix for the issue is made in MySQL 5.7 and later. (Bug #17319380)
• Replication: The server did not handle correctly the insertion of a row larger than 4 GB when using rowbased replication. (Bug #17081415)
• Replication: When using row-based replication, an additional auto-increment column on the slave
version of a table was not updated correctly; a zero was inserted instead. (Bug #17066269, Bug #69680)
• Replication: Statements involving the Performance Schema tables should not be written to the binary
log, because the content of these tables is applicable only to a given MySQL Server instance, and may
differ greatly between different servers in a replication topology. The database administrator should be
able to configure (INSERT, UPDATE, or DELETE) or flush (TRUNCATE TABLE) performance schema
tables on a single server without affecting others. However, when replicating from a MySQL 5.5 master
to a MySQL 5.5 or later slave, warnings about unsafe statements updating Performance Schema
tables were elevated to errors. For MySQL 5.6 and later slaves, this prevented the simultaneous use of
performance_schema and GTIDs (see Replication with Global Transaction Identifiers).
This fix causes all updates on tables in the performance_schema database to be filtered on the
master and not replicated, regardless of the type of logging that is in effect. Prior to this fix, statements
using were handled by being marked as unsafe for replication, which caused warnings during execution;
the statements were nonetheless written to the binary log, regardless of the logging format in effect.
Existing replication behavior for tables in the INFORMATION_SCHEMA database is not changed by this
fix.
For more information, see MySQL Performance Schema. (Bug #16814264)
References: See also: Bug #14741537, Bug #18259193.
• Replication: Modifying large amounts of data within a transaction can cause the creation of temporary
files. Such files are created when the size of the data modified exceeds the size of the binary log cache
(max_binlog_cache_size). Previously, such files persisted until the client connection was closed,
which could allow them to grow until they exhausted all available disk space in tmpdir. To prevent this
from occurring, the size of a temporary file created in this way in a given transaction is now reset to 0
when the transaction is committed or rolled back. (Bug #15909788, Bug #18021493, Bug #66237)
• Replication: The server checks to determine whether semisynchronous replication has been enabled
without a lock, and if this is the case, it takes the lock and checks again. If semisynchronous replication
was disabled after the first but prior to the second one, this could cause the server to fail. (Bug
#14511533, Bug #66411)
References: See also: Bug #17920923.
• Replication: Semisynchronous replication became very slow if there were many dump threads (such
as from mysqlbinlog or slave I/O connections) working at the same time. It was also found that
semisynchronous master plugin functions were called even when the dump connections did not support
73
MySQL 5.6 Release Notes
semisynchronous replication, which led to locking of the plugin lock as well as wasting time on necessary
code.
After this fix, non-semisynchronous dump threads no longer call semisynchronous master functions to
observe binary events. (Bug #70218, Bug #17434690)
• Microsoft Windows: On Microsoft Windows, the rw-lock backup implementation for the my_atomic_*
functions was always used. Now, the native Microsoft Windows implementation is used, where available.
(Bug #18054042)
• mysql_install_db could hang while reading /dev/random to generate a random root password.
(Bug #18395378)
• While printing the server version, the mysql client did not check for buffer overflow in a string variable.
(Bug #18186103)
• Compilation failed if MySQL was configured with CFLAGS set to include a -Werror option with an
argument. (Bug #18173037)
• A shared libmysqld embedded server library was not built on Linux. A new
WITH_EMBEDDED_SHARED_LIBRARY CMake option now makes this possible. (Bug #18123048, Bug
#16430656, Bug #68559)
• Building MySQL from source on Windows using Visual Studio 2008 failed with an identifier not
found error due to a regression introduced by the patch for Bug#16249481. (Bug #18057449)
References: This issue is a regression of: Bug #16249481.
• When tables are reopened from the table cache and the current thread is not instrumented for the
Performance Schema, a table handle was unnecessarily instrumented. (Bug #18047865)
• The SUM_SORT_MERGE_PASSES column value in the events_statements_summary_by_digest
Performance Schema table was calculated incorrectly. (Bug #17938255)
• If the events_statements_summary_by_digest Performance Schema table was full when a
statement with a new digest was found, the Performance_schema_digest_lost status variable was
not incremented. (Bug #17935314)
• The audit log plugin could cause a server exit during log file rotation operations when there were many
operations happening for multiple connections. (Bug #17930339)
• The optimizer could push down a condition when the index did not have the key part present in the
condition. (Bug #17814492)
• Contraction information in a collation could be mishandled, resulting in incorrect decisions about whether
a character is part of a contraction, and miscalculation of contraction weights. (Bug #17760379)
• DROP TRIGGER succeeded even with the read_only system variable enabled. (Bug #17503460)
• If used to process a prepared CALL statement for a stored procedure with OUT or INOUT parameters,
mysql_stmt_store_result() did not properly set the flags required to retrieve all the result sets.
(Bug #14492429, Bug #17849978)
• Aggregating the results of a subquery in the FROM clause could produce incorrect results. (Bug #71244,
Bug #18014565)
• A query that creates a temporary table to find distinct values and has a constant value in the projected
list could produce incorrect results. (Bug #70657, Bug #17634335)
74
MySQL 5.6 Release Notes
• When run by root, mysqld --help --verbose exited with a nonzero error code after displaying the
help message. (Bug #70058, Bug #17324415)
• A deadlock error occurring during subquery execution could cause an assertion to be raised. (Bug
#69969, Bug #17307201)
• A temporal literal string without delimiters and more than 14 digits was validated as a TIMESTAMP/
DATETIME value with a two-digit precision fractional seconds part. But fractional seconds should always
be separated from other parts of a time by a decimal point. (Bug #69714, Bug #17080703)
• For system variables that take a string value, SET statements permitted an unquoted value, but values
that contained dots were parsed incorrectly and only part of the value was assigned. For example, SET
GLOBAL slow_query_log_file = my_slow.log assigned the value my_slow. Now such values
must be quoted or an error occurs. (Bug #69703, Bug #17075846)
• The mysqladmin, mysqlbinlog, mysqlcheck, mysqldump, mysqlimport, mysqlslap, and
mysqlshow programs now support a --secure-auth option that prevents sending passwords to the
server in old (pre-4.1) format. This option is enabled by default; use --skip-secure-auth to disable
it. (Bug #69051, Bug #16723046)
• MySQL client programs from a Community Edition distribution could not connect using SSL to a MySQL
server from an Enterprise Edition. This was due to a difference in certificate handling by yaSSL and
OpenSSL (used for Community and Enterprise, respectively). OpenSSL expected a blank certificate
to be sent when not all of the --ssl-ca, --ssl-cert, and --ssl-key options were specified, and
yaSSL did not do so. To resolve this, yaSSL has been modified to send a blank certificate when an
option is missing. (Bug #68788, Bug #16715064)
• Messages written by the server to the error log for LDML collation definition problems were missing the
collation name. (Bug #68144, Bug #16204175)
• On Windows, mysql_install_db.pl could be run only from within the bin directory under the
installation directory. (Bug #42421, Bug #11751526)
Changes in MySQL 5.6.16 (2014-01-31, General Availability)
Known limitations of this release:
Note
Building MySQL from source on Windows using Visual Studio 2008
fails with an identifier not found error. Later versions of Visual
Studio are unaffected. The workaround is to set the CMake build option,
INNODB_PAGE_ATOMIC_REF_COUNT, to OFF. This option is ON by default.
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Functionality Added or Changed
• Bugs Fixed
Functionality Added or Changed
75
MySQL 5.6 Release Notes
• InnoDB: New global configuration parameters, innodb_status_output and
innodb_status_output_locks, allow you to dynamically enable and disable the standard InnoDB
Monitor and InnoDB Lock Monitor for periodic output. Enabling and disabling monitors for periodic
output by creating and dropping specially named tables is deprecated and may be removed in a future
release. For additional information, see InnoDB Monitors.
• Previously, ALTER TABLE in MySQL 5.6 could alter a table such that the result had temporal columns
in both 5.5 and 5.6 format. Now ALTER TABLE upgrades old temporal columns to 5.6 format for ADD
COLUMN, CHANGE COLUMN, MODIFY COLUMN, ADD INDEX, and FORCE operations. This conversion
cannot be done using the INPLACE algorithm because the table must be rebuilt, so specifying
ALGORITHM=INPLACE in these cases results in an error. Specify ALGORITHM=COPY if necessary.
When ALTER TABLE does produce a temporal-format conversion, it generates a message that can be
displayed with SHOW WARNINGS: TIME/TIMESTAMP/DATETIME columns of old format have
been upgraded to the new format. (Bug #17246318)
• CMake now supports a -DTMPDIR=dir_name option to specify the default tmpdir value. If unspecified,
the value defaults to P_tmpdir in <stdio.h>. Thanks to Honza Horak for the patch. (Bug #68338, Bug
#16316074)
Bugs Fixed
• InnoDB; Replication: Attempting to reset a replication slave while innodb_force_recovery is
greater than 0 would return a cryptic error message: ERROR(1030) HY000: Got error -1 from
storage engine. The error message has been changed to: ERROR HY000: Operation not
allowed when innodb_force_recovery > 0. Replication options such as --relay-loginfo-repository=TABLE and --master-info-repository=TABLE store information in tables
in InnoDB. When innodb_force_recovery is greater than 0, replication tables cannot be updated
which may cause replication administration commands to fail. (Bug #17287443, Bug #69907)
• InnoDB; Replication: Using the InnoDB memcached plugin (see InnoDB memcached Plugin) with
innodb_api_enable_binlog set to 1 caused the server to leak memory. (Bug #70757, Bug
#17675622)
• InnoDB: A boolean mode full-text search query would result in a memory access violation during
parsing. (Bug #17978763)
• InnoDB: When new indexes are added by an ALTER TABLE operation, instead of only saving tablelevel statistics and statistics for the new indexes, InnoDB would save statistics for the entire table,
including the table's other indexes. This behavior slowed ALTER TABLE performance. (Bug #17848838,
Bug #16511145)
• InnoDB: Due to a parser error, full-text search queries that include a sub-expression could return the
wrong result. (Bug #17840768)
• InnoDB: The innochecksum tool did not use a Windows-specific API to retrieve file size information,
which resulted in an incorrect error message (Error: ibdata1 cannot be found) when the
MySQL 5.6 innochecksum 2GB file size limit was exceeded. innochecksum now provides support for
files larger than 2GB in both MySQL 5.6 and MySQL 5.7. (Bug #17810862, Bug #70936)
• InnoDB: Due to a regression introduced by the fix for Bug#17371537, memory was not allocated for the
default memcached engine when using the default memcached engine as the backstore for data instead
of InnoDB. (Bug #17800829)
• InnoDB: InnoDB would report an incorrect operating system error code after failing to initialize. (Bug
#17788055, Bug #70867)
76
MySQL 5.6 Release Notes
• InnoDB: Manipulating a table after discarding its tablespace using ALTER TABLE ... DISCARD
TABLESPACE could result in a serious error. (Bug #17700280)
• InnoDB: Persistent optimizer statistics would cause stalls due to latch contention. (Bug #17699331, Bug
#70768)
• InnoDB: An InnoDB full-text search failure would occur due to an “unended” token. The string and string
length should be passed for string comparison. (Bug #17659310)
• InnoDB: MATCH() ... AGAINST queries that use a long string as an argument for AGAINST() could
result in an error when run on an InnoDB table with a full-text search index. (Bug #17640261)
• InnoDB: In debug builds, a merge insert buffer during a page read would cause a memory access
violation. (Bug #17561188)
• InnoDB: In sync0rw.ic, rw_lock_x_lock_func_nowait would needlessly call
os_thread_get_curr_id. (Bug #17509710, Bug #70417)
• InnoDB: Truncating a memcached InnoDB table while memcached is performing DML operations would
result in a serious error. (Bug #17468031)
• InnoDB: The server could fail to restart if a crash occurred immediately following a RENAME TABLE in
an ALTER TABLE, RENAME TABLE sequence. (Bug #17463290)
• InnoDB: If a tablespace data file path is updated in a .isl file and then a crash recovery is performed,
the updated tablespace data file path is read from the .isl file but the SYS_DATAFILES table would
not be not updated. The SYS_DATAFILES table is now updated with the new data file path after crash
recovery. (Bug #17448389)
• InnoDB: Attempting to rename a table to a missing database would result in a serious error. (Bug
#17447500)
• InnoDB: If the first page (page 0) of file-per-table tablespace data file was corrupt, recovery would be
halted even though the doublewrite buffer contained a clean copy of the page. (Bug #17335427, Bug
#70087, Bug #17341780)
• InnoDB: The InnoDB memcached Readme file (README-innodb_memcached) incorrectly stated that
libevent 1.6.0 is linked statically into daemon memcached. The bundled version of libevent is 1.4.12, not
1.6.0. (Bug #17324419, Bug #70034)
• InnoDB: The ALTER TABLE INPLACE algorithm failed to decrease the auto-increment value. (Bug
#17250787, Bug #69882)
• InnoDB: Comments in btr0cur.cc incorrectly stated that btr_cur_pessimistic_update() and
btr_cur_optimistic_update() would accept a NULL value. (Bug #17231743, Bug #69847)
• InnoDB: dict_table_schema_check would call dtype_sql_name needlessly. (Bug #17193801,
Bug #69802)
• InnoDB: The function os_file_get_status would not work with raw devices. (Bug #17023438, Bug
#69424)
• InnoDB: During crash recovery, an incorrect transaction active time would result in rolling back an
uncommitted transaction. (Bug #16936961, Bug #69438)
• InnoDB: Heap block debugging information (file_name, lineno), used for logging diagnostics, would
appear in release builds. This information should only appear in debug builds. (Bug #16924719, Bug
#69422)
77
MySQL 5.6 Release Notes
• InnoDB: An online ALTER TABLE operation would consume more memory than expected. During an
online ALTER TABLE operation, an online log buffer containing a head and tail buffer is created for each
index that is created or rebuilt. The tail buffer is the writer context and is only required for concurrent
write operations on an index while the ALTER TABLE operation is in progress. The head buffer is the
reader context and is only required during the log apply phase. To reduce memory consumption, the
tail buffer is now allocated when the first DML statement is run on the index, and the head buffer is only
allocated in the log apply phase and freed afterwards. (Bug #16868967, Bug #69325, Bug #17911720)
• InnoDB: Renaming a column while also adding or dropping columns in the same ALTER TABLE
operation would cause an error. (Bug #16864981)
• InnoDB: On Windows, the full-text search (FTS) object ID was not in the expected hexadecimal format.
(Bug #16559254)
References: See also: Bug #16559119.
• InnoDB: Fetching and releasing pages from the buffer pool and tracking the page state are expensive
and complex operations. Prior to the bug fix, these operations were performed using a page mutex.
Using a page mutex to track several things is expensive and does not scale well. The bug fix separates
fetch and release tracking (in-use state) of a page from page I/O state tracking. Fetch and release is now
tracked using atomics where available.
For portability, a new CMake build option, INNODB_PAGE_ATOMIC_REF_COUNT (default ON), can be
used to disable atomic page reference counting on platforms where atomics support is not available.
When atomic page reference counting is enabled (default), “[Note] InnoDB: Using atomics
to ref count buffer pool pages” is printed to the error log at server startup. If atomic page
reference counting is disabled, “[Note] InnoDB: Using mutexes to ref count buffer pool
pages” is printed instead. (Bug #16249481, Bug #68079)
• InnoDB: Table renaming errors would appear in the LATEST FOREIGN KEY ERROR section of the
SHOW ENGINE INNODB STATUS output. (Bug #12762390, Bug #61746)
• InnoDB: UNIV_SYNC_DEBUG, which was disabled in univ.i with the fix for Bug#16720368, is now
enabled. (Bug #69617, Bug #17033591)
• Partitioning: Queries using the index_merge optimization (see Index Merge Optimization) could return
invalid results when run against tables that were partitioned by HASH. (Bug #17588348, Bug #70588)
References: See also: Bug #16862316, Bug #17648468, Bug #18167648.
• Partitioning: When no partition had returned a row since the last HA_ERR_KEY_NOT_FOUND error, the
use of uninitialized memory in the priority queue used for returning rows in sorted order could lead to a
crash of the server. (Bug #17401628)
• Replication: When the binary log I/O cache grew to exactly 32768 bytes and the current transaction was
preceded by a transaction whose size was greater than 32768 bytes, events could be corrupted when
written into the binary log. (Bug #17842137)
• Replication: Creating and dropping large numbers of temporary tables could lead to increased memory
consumption. (Bug #17806014)
• Replication: When log_warnings is greater than 1, the master prints binary log dump thread
information—containing the slave server ID, binary log file name, and binary log position—in
mysqld.1.err. A slave server ID greater than 2 billion was printed with a negative value in such cases.
(Bug #17641586, Bug #70685)
• Replication: mysqlbinlog --verbose failed when it encountered a corrupt row event in the binary
log. Such a row event could also cause the slave to fail. (Bug #17632978)
78
MySQL 5.6 Release Notes
References: See also: Bug #16960133.
• Replication: mysqlbinlog did not properly decode DECIMAL values in a row-based binary log. This
could cause invalid values to be printed out for DECIMAL columns. (Bug #17544169)
References: See also: Bug #14309019.
• Replication: Seconds_Behind_Master in the output of SHOW SLAVE STATUS could under some
conditions be reported as 0 when it should have had a value greater than zero. (Bug #17233214)
References: See also: Bug #16579028.
• Replication: Invalid event offsets in the binary log were not always handled correctly, which could lead
to replication failure. (Bug #16736412, Bug #69087)
• Replication: The semisynchronous replication plugin was called twice for a DDL statement,
incrementing Rpl_semi_sync_master_yes_tx by 2 instead of 1 each time such a statement was
executed. (Bug #70410, Bug #17509011)
• Microsoft Windows: On Windows, the --local-service server option did not work, and was not
displayed in the --help message. (Bug #69637, Bug #17049656)
• FORCE INDEX [FOR ORDER BY] (index_name) did not work for joins.
The fix for this bug also changes the warning created for EXPLAIN. Instead of printing only {IGNORE|
USE|FORCE} INDEX it now also prints FOR {GROUP BY|ORDER BY|JOIN} if that was specified in the
query. (Bug #17889511)
• With the compressed client/server protocol enabled, Performance Schema statement instrumentation
could raise an assertion. (Bug #17794846)
• An assertion could be raised if a filesort failed to resize its main buffer when record properties
changed. (Bug #17757914)
• In some cases, UNIX_TIMESTAMP() could return NULL when it should return 0. (Bug #17728371)
• The cache used for the Index Merge access method was freed only after successful retrieval of all rows.
Interruption or failure of the operation led to a file descriptor leak. (Bug #17708621)
• Using the mysqldump --set-gtid-purged option with no value caused mysqldump to crash. (Bug
#17650245)
• A race condition between Performance Schema statement event threads led to a server exit. (Bug
#17637970)
• In a view definition requireing resolution of aggregrate expressions within a subquery to an outer query,
selecting from the view could cause a server exit. (Bug #17547804)
References: This issue is a regression of: Bug #16436383.
• An addressing error in accessing the join buffer could produce invalid results or a server exit. (Bug
#17513341)
• mysql_config incorrectly included some flags to generate compiler warning output. (Bug #17400967)
• With semi-join optimization enabled, queries with nested subqueries could cause a server exit due to
incorrect resolution of references to columns in the middle query block. (Bug #17398972)
79
MySQL 5.6 Release Notes
• In some cases, the optimizer wrote fixed-length temporary MyISAM tables to disk rather than variablelength temporary tables. (Bug #17231940)
• Enabling the validate_password plugin could result in incorrect password hashes being stored in the
mysql.user table. (Bug #17065383)
• For accounts authenticated using the sha256_password plugin, setting the password after the
password had been expired did not clear the password-expired flag. (Bug #16872181)
• On OS X 10.7, a race condition involving vio_shutdown() and the select-based implementation of
vio_io_wait() could cause a server exit. (Bug #16354789, Bug #17733393)
• Host names in example URLs used within the source code were replaced by names in the example.com
domain, the domain intended by IANA for this purpose. (Bug #15890092)
• For utf8 and utf8mb4 strings, handler functions unnecessarily called a Unicode conversion function.
(Bug #14057034)
• Several -W warning flags were turned off for compilation in maintainer mode if MySQL was configured
with -DWITH_INNODB_MEMCACHED=1. (Bug #13898319)
• Calling the ExtractValue() function with an invalid XPath expression could in some cases lead to a
failure of the server. (Bug #12428404, Bug #61065)
• Use of a nonmultibyte algorithm for skipping leading spaces in multibyte strings could cause a server
exit. (Bug #12368495, Bug #18315770)
• With ONLY_FULL_GROUP_BY SQL mode enabled, a query that uses GROUP BY on a column derived
from a subquery in the FROM clause failed with a column isn't in GROUP BY error, if the query was
in a view. (Bug #11923239)
• mysqldump --single-transaction acquired metadata locks for each dumped table but did not
release them until the dump operation finished. Consequently, other DDL operations on a dumped table
blocked even after the table itself had been dumped. mysqldump now attempts to release metadata
locks earlier. (Bug #71017, Bug #17862905)
• sql_resolver.cc referred to partitioning code that should have been protected by an #ifdef, even
when MySQL was configured with -DWITH_PARTITION_STORAGE_ENGINE=OFF. (Bug #71010, Bug
#17876794)
• Several issues identified by the Coverity static analysis tool were fixed. Thanks to Honza Horak for the
patch. (Bug #70830, Bug #17760511)
• The prototype of the Performance Schema instrumentation API mysql_cond_timedwait() call was
fixed to be drop-in compatible with pthread_cond_timedwait(). This fix affects only implementers of
third-party plugins. (Bug #70628, Bug #17702677)
• An incorrect result could be returned for a query with an IF() predicate in the WHERE clause combined
with OUTER JOIN in a subquery that is transformed to a semi-join. (A workaround is to disable semi-join
using SET optimizer_switch='semijoin=off';) (Bug #70608, Bug #17600176)
• Complex updates of Performance Schema tables involving joins or subqueries failed to update every
row. (Bug #70025, Bug #17309657)
• Some files in the file_instances Performance Schema table were not being removed because the
file-removal operation was not instrumented. (Bug #69782, Bug #17209750)
• For the path specified with the --basedir option, mysql_plugin attempted to unlink the path rather
than free the memory in which the path was stored. (Bug #69752, Bug #17168602)
80
MySQL 5.6 Release Notes
• It was not possible to query a view with an ORDER BY clause that referenced an alias in the SELECT
clause of the view definition, unless all columns in the view were named in the select list.
To handle this problem, the server now writes a view differently into the .frm file that stores the view
definition. If you experience view-evaluation errors such as just described, drop and recreate the view so
that the .frm file contains the updated view representation. (Bug #69678, Bug #17077305)
• For the utf8_bin collation, ORDER BY LOWER(col_name) could produce incorrect ordering. (Bug
#69005, Bug #16691598)
• A full-text search combined with derived tables (subqueries in the FROM clause) caused a server exit.
Now if a full-text operation depends on a derived table, the server produces an error indicating that a fulltext search cannot be done on a materialized table. (Bug #68751, Bug #16539903)
• COUNT(DISTINCT) sometimes produced an incorrect result when the last read row contained a NULL
value. (Bug #68749, Bug #16539979, Bug #71028, Bug #17867117)
• Some scripts displayed out-of-date information regarding where to report bugs. (Bug #68742, Bug
#16530527)
• Updating a FEDERATED table with UPDATE... JOIN caused a server exit when the local table
contained a single row and that row could be joined to a row in the FEDERATED table. (Bug #68354, Bug
#16324629)
• The make_atomic_cas_body64 implementation on IA32 with gcc but without gcc builtins could be
miscompiled due to an incorrect constraint. The patch also causes MySQL to use builtin atomics when
compiled using Clang. (Bug #63451, Bug #17242996)
• mysql_install_db referred to the obsolete mysqlbug script for reporting problems. It now refers to
http://bugs.mysql.com/ instead. (Bug #29716, Bug #11746921)
Changes in MySQL 5.6.15 (2013-12-03, General Availability)
A known limitation of this release:
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Packaging Notes
• Functionality Added or Changed
• Bugs Fixed
Packaging Notes
• Previously, MySQL Server distributions included the MySQL Reference Manual in Info format (the Docs/
mysql.info file). Because the license for the manual restricts redistribution, its inclusion in Community
packages caused problems for downstream redistributors, such as those who create Linux distributions.
Community distributions of MySQL Server no longer include the mysql.info file, to make the repackaging
and redistribution process easier (for example, the source tarball and its checksum can be used directly).
81
MySQL 5.6 Release Notes
This change applies to all source and binary Community packaging formats. Commercial (Enterprise)
distributions are unchanged.
For those who wish to continue using the MySQL Reference Manual in Info format, we have made it
available at http://dev.mysql.com/doc/.
Functionality Added or Changed
• Incompatible Change: Several statement instruments in the setup_instruments table are used by
the Performance Schema during the early stages of statement classification before the exact statement
type is known. These instruments were renamed to more clearly reflect their “abstract” nature:
Old Instrument Name
New Instrument Name
statement/com/
statement/abstract/new_packet
statement/com/Query
statement/abstract/Query
statement/rpl/relay_log
statement/abstract/relay_log
In addition, statistics for abstract instruments are no longer collected in the following tables, because no
such instrument is ever used as the final classification for a statement:
events_statements_summary_by_thread_by_event_name
events_statements_summary_by_account_by_event_name
events_statements_summary_by_user_by_event_name
events_statements_summary_by_host_by_event_name
events_statements_summary_global_by_event_name
Applications that refer to the old instrument names must be updated with the new names. For more
information about the use of abstract instruments in statement classification, see Performance Schema
Statement Event Tables. (Bug #16750433, Bug #17271055)
• The Performance Schema now instruments the read/write lock Delegate::lock, which is used for the
following classes:
Trans_delegate
Binlog_storage_delegate
Binlog_transmit_delegate
Binlog_relay_IO_delegate
A different instrument name is used for each subclass, to have distinct statistics for distinct uses. The
instruments are visible in the schema.setup_instruments table and have these names:
wait/synch/rwlock/sql/Trans_delegate::lock
wait/synch/rwlock/sql/Binlog_storage_delegate::lock
wait/synch/rwlock/sql/Binlog_transmit_delegate::lock
wait/synch/rwlock/sql/Binlog_relay_IO_delegate::lock
(Bug #17590161, Bug #70577)
• A new CMake option, WITH_ASAN, permits enabling AddressSanitizer for compilers that support it. (Bug
#17435338)
• The hash function used for metadata locking was modified to reduce overhead. (Bug #68487, Bug
#16396598)
Bugs Fixed
82
MySQL 5.6 Release Notes
• InnoDB; Replication: The InnoDB mecached plugin would update a record before inserting to the
binary log, which would cause slave server replication to stop. The insert should occur before the
update. (Bug #17358875)
• InnoDB: A regression introduced by the fix for Bug#17371537 resulted a memory leak for memcached
insert operations. (Bug #17738935)
References: See also: Bug #17371537.
• InnoDB: Fault-tolerant code found in the log apply code for InnoDB ALTER TABLE ... IN PLACE
could result in data corruption. (Bug #17625063, Bug #17512497)
• InnoDB: The trx->error_key_num field was not initialized in the error injection code found in
storage/innobase/handler/handler0alter.cc. The error_key_num field is usually 0 but can
be a non zero value if the memory buffer of a DDL transaction object is reused. (Bug #17624926)
• InnoDB: Databases names beginning with a digit would cause a full-text search (FTS) parser error. (Bug
#17607956)
References: See also: Bug #17161372.
• InnoDB: An ALTER TABLE ... CHANGE [COLUMN] operation would result in an
rbt_empty(index_cache->words) assertion. (Bug #17536995)
• InnoDB: CHECK TABLE would ignore the QUICK option. (Bug #17513737)
• InnoDB: An excessive amount of memory would be consumed when querying
INFORMATION_SCHEMA.INNODB_FT_INDEX_TABLE. The problem would occur for very large full-text
search indexes. (Bug #17483582, Bug #70329)
• InnoDB: Running SHOW ENGINE INNODB STATUS on one connection thread and killing that thread
by running a KILL CONNECTION statement from a different connection thread would result in a severe
error. (Bug #17474166)
• InnoDB: In debug builds, test case failures would occur due to ibuf_contract_ext performing
merges and dict_stats_update returning evicted pages back into the buffer pool while
ibuf_change_buffering_debug is enabled. (Bug #17446090)
• InnoDB: Setting the O_DIRECT flag on a file on tmpfs on some operating systems would result in an
error printed to the error log. Creating multiple temporary tables on tmpfs would cause the error to be
printed repeatedly. The error message has been changed to a warning that is only printed once when
running CREATE TABLE multiple times. (Bug #17441867)
• InnoDB: InnoDB failed to return an error when attempting to run a query after discarding the
tablespace. (Bug #17431533)
• InnoDB: A severe error would occur after discarding a tablespace. (Bug #17430207)
• InnoDB: The information_schema.innodb_metrics index_merge counter was not incremented
in btr0btr.cc. This patch also introduces new counters (index_page_reorg_attempts,
index_page_reorg_successful and index_page_discards) and renames the
index_merges counter to “index_page_merge_attempts” to distinguish it from the
index_page_merge_successful counter. (Bug #17409657, Bug #70241)
• InnoDB: During a TRUNCATE TABLE operation, InnoDB: Trying to TRUNCATE a missing
index of table ... warnings would be printed to the error log. These warnings should not be
printed when the index is a full-text search (FTS) index. (Bug #17402002, Bug #70226)
83
MySQL 5.6 Release Notes
References: See also: Bug #12429565.
• InnoDB: During parallel full-text search (FTS) index creation, a scanner thread reads in documents
and passes them to the tokenizer. The tokenizer frees documents from memory when tokenization is
complete. When tokenizing documents with a large amount of text, the tokenizer thread would not keep
pace with the scanner thread. As a result, memory would not be freed fast enough and the “tokenization
pending list” would grow in size. (Bug #17384979)
• InnoDB: trx_create and trx_free would be called for every memcached get request. (Bug
#17371537, Bug #70172)
• InnoDB: A full-text search (FTS) BOOLEAN MODE query with an invalid character in the query string
could result in a memory access violation failure. (Bug #17350055)
• InnoDB: Full-text index creation on a large table failed due to insufficient temporary table space and
result in a misleading “incorrect key file” error. (Bug #17339606)
• InnoDB: In btr_validate_level there are checks to ensure that all B-tree pages are marked when
allocated. The checks failed on the change buffer because the allocation of change buffer pages is
handled differently than other B-tree pages. (Bug #16884217)
• InnoDB: The hardcoded size for the srv_max_n_threads variable was insufficient. The variable
setting is now configured based on the maximum number of connection threads and InnoDB
background threads. (Bug #16884077)
• InnoDB: A SELECT COUNT(*) query would take a long time to complete when run concurrently with
a LOAD DATA operation. The mtr_memo_contains function, which determines if an object is part
of a memo in a mini transaction, contained a nested loop that caused the query to run slowly. (Bug
#16764240, Bug #69141)
• InnoDB: When the change buffer is enabled, InnoDB failed to write a transaction log record when
merging a record from the insert buffer to a secondary index page if the insert was performed as an
“update-in-place”. (Bug #16752251, Bug #69122)
• InnoDB: An existing full-text index would become invalid after running ALTER TABLE ADD FULLTEXT
due to an unsynchronized full-text cache. (Bug #16662990, Bug #17373659)
• InnoDB: Due to a regression in MySQL 5.6, creating or dropping tables with
innodb_force_recovery set to 3 (SRV_FORCE_NO_TRX_UNDO) failed. Additionally, this bug fix
includes a code modification that sets InnoDB to read-only when innodb_force_recovery is set to a
value greater than 3 (SRV_FORCE_NO_TRX_UNDO). (Bug #16631778, Bug #69892)
• InnoDB: An InnoDB memcached configuration error message contained an incorrect file name.
The error message stated, Please create config table containers in database
innodb_memcache by running innodb_config.sql. error 31. The correct file name
is innodb_memcached_config.sql. Also, the “error 31” portion of the error message has been
translated to its text equivalent, which is “Table not found”. (Bug #16498810, Bug #68684)
• InnoDB: In mutex_spin_wait(), the sync_array_reserve_cell function could fail to find an
empty slot on systems with sync wait arrays that are small in size, resulting in an error. (Bug #16245498)
• InnoDB: Full-text search (FTS) index savepoint information would not be set resulting in a severe error
when attempting to rollback to the savepoint. (Bug #14639605, Bug #17456092)
• InnoDB: When index_read_map is called for an exact search and fails to return a record due to nonmatching search criteria, the cursor would be positioned on the next record after the searched key. A
84
MySQL 5.6 Release Notes
subsequent call to index_next would return the next record instead of returning the previous nonmatching row, thereby skipping a record. (Bug #14621190, Bug #15965874, Bug #17314241, Bug
#70038, Bug #17413093, Bug #12860669, Bug #60220, Bug #17565888)
• InnoDB: An implicit rollback caused the server to halt when restarting with an
innodb_force_recovery value of 3 or greater. This bug was addressed by the combination of fixes
for Bug #16310467 and Bug #17253499. (Bug #14178835)
References: See also: Bug #16310467, Bug #17253499.
• InnoDB: Converting a table with a large number of columns from MyISAM to InnoDB would cause an
assertion due to insufficient log buffer space. Instead of asserting, InnoDB now attempts to increase log
buffer size automatically if the redo log size is too large. (Bug #11758196, Bug #50366)
• Partitioning: The storage engine was set incorrectly during a rebuild of a partition; the table storage
engine was ignored and the default storage engine used instead. Thus, in MySQL 5.1, it was possible
for REBUILD PARTITION to change the partition storage engine from InnoDB to MyISAM, and for the
reverse (rebuilding partitions of MyISAM tables causing the partitions to use InnoDB) to occurin MySQL
5.5 and later. Now, when rebuilding partitions, the storage engine actually used by the table is checked
and used by the handler for the rebuild operation, so that the partition storage engine is not inadvertently
changed. (Bug #17559867)
• Partitioning: After disabling the parent table's indexes with ALTER TABLE ... DISABLE KEYS,
rebuilding any of its partitions enabled the indexes on those partitions, leading MyISAM to fail with an
error when the optimizer tried to use one of the affected indexes.
Now in such cases, we check for disabled indexes on the table before rebuilding any of its partitions.
If the indexes have been disabled, then we disable them on the partition following the rebuild. (Bug
#16051817)
• Replication: A replication master did not handle correctly the disabling of the semisync plugin on the
master and the slave, with a subsequent stopping of the slave. (Bug #17460821, Bug #70349)
• Replication: The final argument in the SET clause of a LOAD DATA ... SET statement was repeated
in the binary log. (Bug #17429677, Bug #70277)
• Replication: When an error encountered by the dump thread while reading events from the active binary
log file was a temporary error, so that the dump thread tried to read the event, it was possible for the
dump thread to seek the wrong position, which could cause one or more events to be resent. To prevent
this, the thread's position is obtained after each correct read of an event.
In addition, with this fix, only binary logs that are not closed normally are marked as possibly being
corrupted.
Finally, two warnings are added; these are now returned when a dump thread encounters a temporary
error. (Bug #17402313)
• Replication: Setting rpl_semi_sync_master_enabled while the master was waiting for a reply from
the slave could in some cases cause the master to fail. (Bug #17327454, Bug #70045)
• Replication: When stopping the I/O thread, it was possible with a very large transaction (equivalent to
a binary log size greater than 100MB) that the thread did not receive the transaction to the end. When
reconnecting with MASTER_AUTO_POSITION=1 it then tried to fetch changes from the next transaction,
which could lead to loss of the incomplete transaction and its data. (Bug #17280176, Bug #69943)
• Replication: Trying to set CHANGE MASTER TO ... MASTER_AUTO_POSITION = 0 failed with error
1777 (ER_AUTO_POSITION_REQUIRES_GTID_MODE_ON). (Bug #17277744)
85
MySQL 5.6 Release Notes
• Replication: The value of LAST_INSERT_ID() was not correctly replicated when filtering rules were
used on the slave. (Bug #17234370, Bug #69861)
• Replication: An internal function used for storing GTID values could sometimes try to handle them as
strings of the wrong length. (Bug #17032712, Bug #69618)
• Replication: During row-based replication with binlog_row_image set to MINIMAL, updating only
some columns of a table having 9 or more columns caused mysqlbinlog to fail when it was used with
the --verbose option. (Bug #16960133)
• Replication: Issuing a GRANT statement with invalid parameters caused the master to write
LOST_EVENTS events into its binary logs, causing replication to stop. Now such cases, if one or more
grants or revocations of privileges are successful, an incident is written to the log; otherwise, only a
warning is logged. (Bug #16629195, Bug #68892)
• libmysqlclient version 18 files were removed from MySQL-shared-compat RPM packages to
avoid a conflict between the MySQL-shared and MySQL-shared-compat RPM packages. (Bug
#17749617)
• Enabling Index Merge optimizer switches and setting a small sort_buffer_size value could lead to a
server exit. (Bug #17617945)
• Some license and documentation files were missing from Windows MSI packages. (Bug #17584523)
• Semi-join materialization strategy was not used for VARCHAR columns longer than 512 bytes, resulting in
use of a less-efficient strategy and worse query performance. (The limit in characters rather than bytes
depends on the column character set; 170 characters for utf8, for example.) (Bug #17566396)
• Using MySQL Installer to install MySQL on Windows, then using Uninstall a Program in the Control
Panel to uninstall MySQL, resulted in the MySQL service entry not being removed. (Bug #17550741)
• Selecting from the session_connect_attrs Performance Schema table under high load could cause
a server exit. (Bug #17542370)
• Compilation failures under Visual Studio 2012 were corrected. (Bug #17430236)
• An assertion was raised if SET PASSWORD was used for an account that has been manually deleted
from the mysql.user table but still present in memory. (Bug #17359329)
• The CLIENT_CONNECT_WITH_DB flag was improperly handled in the C client library. This could lead to
a malformed packet sent to the server. (Bug #17351732)
• The filesort implementation sometimes failed to allocate enough buffer space, leading to a server
exit. (Bug #17326567)
• The mysql_options() C API function could leak memory if called more than once with the
MYSQL_SET_CLIENT_IP option. (Bug #17297012)
• The CONV() function could call abs(INT_MIN), which is undefined, and cause a server exit. (Bug
#17296644)
• An error array in the SSL code was missing a comma, leading to implicit concatenation of adjacent
messages and a resulting off-by-one error in the relationship between error numbers and messages.
(Bug #17294150)
• GRANT without an IDENTIFIED BY clause resulted in an error even for existing users. (Bug #16938568)
• GROUP_CONCAT() with an invalid separator could cause a server exit. (Bug #16870783)
86
MySQL 5.6 Release Notes
• An internal InnoDB string routine could write past the end of a buffer. (Bug #16765410)
• For uninstall operations, the MySQL Server MSI installer failed to remove some files if the server was
running. This could lead to problems for a subsequent installation of a lower MySQL version: The
installer reported a successful operation but not some of the files from the original installation were not
replaced by their lower-versioned counterparts. (Bug #16685125)
• GIS intersection-related code was missing a return value check, leading to a loop in nondebug builds
and a raised assertion in debug builds. (Bug #16659166)
• Using the binary client/server protocol, the second execution of a prepared statement for a query with
parameters in the LIMIT clause raised an assertion. (Bug #16346241)
• For upgrades using the Windows MSI package installer, the upgrade dialog message was missing the
“from” version. (Bug #16053094)
• Very long database names in queries could cause the server to exit. (Bug #15912213, Bug #16900358)
• Standalone Windows MSI packages did not have the ALLUSERS property set. They now set
ALLUSERS=1. For earlier MSI packages in this MySQL series, a workaround is to use the following
command:
C:\> msiexec /i msi_installer_name ALLUSERS=1
(Bug #14647206)
• Recursion by functions called as arguments to XPath expressions was not handled correctly, sometimes
causing such expressions to fail. (Bug #14040071)
• Some .pdb files were missing from Windows Zip archive distributions. (Bug #13878021)
• Several issues identified by the Coverity static analysis tool were fixed. Thanks to Jan Staněk and Honza
Horak for the patches. (Bug #70591, Bug #17590095)
• Setting host_cache_size at startup had no effect. (Bug #70552, Bug #17576516)
• MySQL did not compile on OS X 10.9 (Mavericks). (Bug #70542, Bug #17647863)
• In some cases, range conditions over indexes defined on column prefixes returned incomplete result
sets. (For example, SELECT ... WHERE 'abcdef1' < col_name AND col_name < 'abcdef9',
where the index on col_name indexed only the first 6 characters.) (Bug #70341, Bug #17458273)
• InnoDB full-text searches failed to find records within transactions that included savepoints. (Bug
#70333, Bug #17458835)
• If asked to upgrade a server that was running without InnoDB enabled, mysql_upgrade issued
complaints about InnoDB tables not existing (tables that will not exist unless InnoDB is available). (Bug
#70152, Bug #17361912)
• With the thread pool plugin enabled, the PROCESSLIST_USER and PROCESSLIST_HOST columns of the
threads Performance Schema table were always NULL for client sessions. Also, for the main thread,
those columns were not NULL but set to a user account.
Note
As part of the bug fix implementation, Performance Schema instrumentation for
the thread pool plugin was changed to use thread_pool, not sql.
87
MySQL 5.6 Release Notes
(Bug #70028, Bug #17310065, Bug #17049691)
• Performance Schema instrumentation overhead was reduced for frequent connect/disconnect
operations. (Bug #70018, Bug #17310878)
• COUNT(DISTINCT) should not count NULL values, but they were counted when the optimizer used
Loose Index Scan. (Bug #69841, Bug #17222452)
• In debug builds, static initialization code could call DBUG functions before the DBUG subsystem was
initialized. (Bug #69653, Bug #17063675)
• Some INSERT INTO ... SELECT ... FROM statements were slow unless the tmp_table_size
and max_heap_table_size system variables were set large enough to permit the temporary table
used for query processing to be stored in the MEMORY storage engine. (Bug #69368, Bug #16894092)
• Some possible cases of memory use after being freed were fixed. Thanks to Jan Staněk for the patch.
(Bug #68918, Bug #16725945)
• Missing va_end() calls were added to logging and UCS2 code. Thanks to Jan Staněk for the patch.
(Bug #68896, Bug #16725769)
• For queries of the form UPDATE ... WHERE unique_key ORDER BY ... LIMIT ..., incorrect
rows could be updated. Unique keys permit multiple NULL values, but the optimizer did not always
consider all of them. (Bug #68656, Bug #16482467)
• For an ALTER TABLE statement that renamed or changed the default value of a BINARY column, the
alteration was done using a table copy and not in place. (Bug #67141, Bug #14735373, Bug #69580,
Bug #17024290)
• The server uses the ethernet hardware address for UUID generation, but made assumptions about the
names of ethernet devices rather than querying the system for their names. Thanks to Honza Horak for
the patch. (Bug #63055, Bug #13548252)
• Host names in grant tables are stored in lowercase, but mysql_install_db could fail to observe
this convention, leading to accounts that could not be dropped with DROP USER. (Bug #62255, Bug
#12917164, Bug #62254, Bug #12917151)
• Killing a query that is performing a filesort operation resulted in an ER_SERVER_SHUTDOWN (Server
shutdown in progess) error. (Bug #18256, Bug #11745656)
Changes in MySQL 5.6.14 (2013-09-20, General Availability)
A known limitation of this release:
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Audit Log Notes
• Functionality Added or Changed
88
MySQL 5.6 Release Notes
• Bugs Fixed
Audit Log Notes
• MySQL 5.7 changed audit log file output to a new format that has better compatibility with Oracle Audit
Vault. This format has been backported to MySQL 5.6 and it is possible to select either the old or new
format using the new audit_log_format system variable, which has permitted values of OLD and NEW
(default OLD). For details about each format, see The Audit Log File.
In addition, when the audit log plugin rotates the audit log file, it uses a different file name format. For
a log file named audit.log, the plugin previously renamed the file to audit.log.TIMESTAMP. The
plugin now renames the file to audit.log.TIMESTAMP.xml to indicate that it is an XML file.
If you change the value of audit_log_format, use this procedure to avoid writing log entries in one
format to an existing log file that contains entries in a different format:
1. Stop the server.
2. Rename the current audit log file manually.
3. Restart the server with the new value of audit_log_format. The audit log plugin will create a new
log file, which will contain log entries in the selected format.
The API for writing audit plugins has also changed. The mysql_event_general structure has new
members to represent client host name and IP address, command class, and external user. For more
information, see Writing Audit Plugins.
Functionality Added or Changed
• Incompatible Change: In MySQL 5.6.13, the statement/com/ abstract statement instrument in the
setup_instruments Performance Schema table was renamed to statement/com/new_packet.
That change has been reverted.
Applications that refer to the old instrument name must be updated with the new name. For more
information about the use of abstract instruments in statement classification, see Performance Schema
Statement Event Tables. (Bug #16750433, Bug #17271055)
• InnoDB: The InnoDB memcached plugin now supports inserts and reads on mapped InnoDB tables
that have an INTEGER defined as the primary key. (Bug #17315083, Bug #17203937)
Bugs Fixed
• Important Change; Replication: START SLAVE UNTIL SQL_AFTER_GTIDS did not cause the slave
to stop until the next GTID event was received following execution of the transaction having the indicated
GTID, which could cause issues in the case when the next GTID event is delayed, or does not exist.
Now the slave stops after completing the transaction with that GTID. (Bug #14767986)
• InnoDB; Partitioning: Following any query on the INFORMATION_SCHEMA.PARTITIONS
table, InnoDB index statistics as shown in the output of statements such as SELECT * FROM
INFORMATION_SCHEMA.STATISTICS were read from the last partition, instead of from the partition
containing the greatest number of rows. (Bug #11766851, Bug #60071)
References: See also: Bug #16882435, Bug #69179.
• InnoDB: When logging the delete-marking of a record during online ALTER TABLE...ADD PRIMARY
KEY, InnoDB writes the transaction ID to the log as it was before the deletion or delete-marking of the
record. When doing this, InnoDB would overwrite the DB_TRX_ID field in the original table, which could
result in locking issues. (Bug #17316731)
89
MySQL 5.6 Release Notes
• InnoDB: The row_sel_sec_rec_is_for_clust_rec function would incorrectly prepare to compare
a NULL column prefix in a secondary index with a non-NULL column in a clustered index. (Bug
#17312846)
• InnoDB: An assertion would be raised in fil_node_open_file due to a missing .ibd file. Instead of
asserting, InnoDB should return false and the caller of fil_node_open_file should handle the return
message. (Bug #17305626, Bug #70007)
• InnoDB: An incorrect purge would occur when rolling back an update to a delete-marked record. (Bug
#17302896)
• InnoDB: The assertion ut_ad(oldest_lsn <= cur_lsn) in file buf0flu.cc failed because the
current max LSN would be retrieved from the buffer pool before the oldest LSN. (Bug #17252421)
• InnoDB: InnoDB memcached add and set operations would perform more slowly than SQL INSERT
operations. (Bug #17214191)
• InnoDB: As commented in log0log.h, old_lsn and old_buf_free should only be compiled when
UNIV_LOG_DEBUG is enabled. (Bug #17160270, Bug #69724)
• InnoDB: Adding a foreign key with a constraint name that included the string “_ibfk_” caused InnoDB
to create a duplicate constraint with a generated internal name. The generated internal name could also
collide with an existing user-defined constraint of the same name, causing a duplicate key error. (Bug
#17076737, Bug #69693, Bug #17076718, Bug #69707)
• InnoDB: The ha_innobase::clone function would incorrectly assert that a thread cannot clone a
table handler that is used by another thread, and that the original table handler and the cloned table
handler must belong to the same transaction. The incorrect assertions have been removed. (Bug
#17001980)
• InnoDB: A regression introduced in the fix for Bug #14606334 would cause crashes on startup during
crash recovery. (Bug #16996584)
• InnoDB: Rolling back an INSERT after a failed BLOB write would result in an assertion failure. The
assertion has been modified to allow NULL BLOB pointers if an error occurs during a BLOB write. (Bug
#16971045)
• InnoDB: When dropping all indexes on a column with multiple indexes, InnoDB failed to block a DROP
INDEX operation when a foreign key constraint requires an index. (Bug #16896810)
• InnoDB: An assertion failure would occur in file row0log.cc on ROW_FORMAT=REDUNDANT tables that
contained an unexpected but valid data directory flag. (Bug #16863098)
• InnoDB: A regression introduced with the fix for Bug #11762038 would cause InnoDB to raise an
incorrect error message. The message stated that, “InnoDB cannot delete/update rows with cascading
foreign key constraints that exceed max depth of 20”. The error message would occur when killing
connections reading from InnoDB tables that did not have foreign key constraints. (Bug #16710923)
References: This issue is a regression of: Bug #11762038.
• InnoDB: In debug builds, an assertion failure would occur if innodb_log_group_home_dir
does not exist. Instead of an assertion, InnoDB now aborts with an error message if
innodb_log_group_home_dir does not exist. (Bug #16691130, Bug #69000)
• InnoDB: For the Barracuda file format and beyond, the externally stored prefix would be read even
though the prefix is already stored locally in memory. (Bug #16569640)
• InnoDB: When changing the shared tablespace file name using innodb_data_file_path and
leaving the current log files in place, InnoDB would create a new tablespace file and overwrite the
90
MySQL 5.6 Release Notes
log files resulting in a mismatch between the data dictionary and tables on disk. This bug fix ensures
that InnoDB does not create a new tablespace if there are inconsistent system tablespaces, undo
tablespaces, or redo log files. (Bug #16418661)
• InnoDB: Persistent statistics would be disabled unnecessarily when running in read-only mode. When
running in read-only mode, fetching statistics from disk does not involve any modification of on-disk data
except for when ANALYZE TABLE is run. This fix enables persistent statistics for read-only mode. (Bug
#16083211)
• InnoDB: The documentation incorrectly stated that START TRANSACTION WITH CONSISTENT
SNAPSHOT provides a consistent snapshot only if the current isolation level is REPEATABLE READ or
SERIALIZABLE. START TRANSACTION WITH CONSISTENT SNAPSHOT only works with REPEATABLE
READ. All other isolation levels are ignored. The documentation has been revised and a warning is now
generated whenever the WITH CONSISTENT SNAPSHOT clause is ignored. (Bug #14017206, Bug
#65146)
• InnoDB: The srv_master_thread background thread, which monitors server activity and performs
activities such as page flushing when the server is inactive or in a shutdown state, runs on a one second
delay loop. srv_master_thread failed to check if the server is in a shutdown state before sleeping.
(Bug #13417564, Bug #63276)
• InnoDB: An infinite loop could occur in buf_page_get_gen when handling compressed-only pages.
(Bug #12560151, Bug #61132)
• Partitioning: Creating a table t1 using CREATE TABLE ... PARTITION BY LIST ...
PARTITION ... VALUES IN (NULL), then attempting to execute CREATE TABLE ... LIKE t1
caused the server to fail. (Bug #16860588)
• Replication: The server attempted to perform an internal truncatation of the slave_worker_info
table while resetting it, even though this is a DDL operation and should not be used conccurrently with
DML operations. To prevent this from happening, the reset now performs sequential row deletion in
place of the truncation operation. (Bug #17286858, Bug #69898)
• Replication: When the --relay-log-info-file option was used together with --slaveparallel-workers set to a value greater than 1, mysqld failed to start. (Bug #17160671)
• Replication: The commit error caused by the failure of binary log rotation failure generated an incident
event in the binary log file and interrupted the user session with error messages which did not mention
that the slave server would be stopped later when the incident event was replayed.
Now, when encountering binary log rotation failure, a more helpful error message is instead written to the
log, alerting the user to investigate in a timely manner. (Bug #17016017)
• Replication: It was possible in CHANGE MASTER TO statements to set the MASTER_DELAY option
greater than the supported maximum value (231 − 1). In addition, the error resulting from setting
MASTER_DELAY to a value greater than 232 was not handled correctly. (Bug #16820156, Bug
#16960315, Bug #69249, Bug #69469)
• Replication: When a master with semisynchronous replication enabled was shut down, the master
failed to wait for either a semisyncnronous ACK or timeout before completing the shutdown. This
prevented semisynchronous replication from reverting to asynchronous replication and allowed open
transactions to complete on the master, which resulted in missing events on the slave.
To fix this problem, dump threads are now stopped last during shutdown, after the client is told to stop,
so that, if the dump thread has pending events from active clients, they can be sent to the slave. (Bug
#16775543)
91
MySQL 5.6 Release Notes
• Replication: A session attachment error during group commit causes the rollback of the transaction (as
intended), but the transaction in which this happened was still written to the binary log and replicated to
the slave. Thus, such an error could lead to a mismatched master and slave.
Now when this error occurs, an incident event is written in the binary log which causes replication
to stop, and notifies the user that redundant events may exist in the binary log. An additional error
is also now reported to the client, indicating that the ongoing transaction has been rolled back. (Bug
#16579083)
• Replication: START SLAVE failed when the server was started with the options --master-inforepository=TABLE relay-log-info-repository=TABLE and with autocommit set to 0,
together with --skip-slave-start.
A workaround for previous versions of MySQL is to restart the slave mysqld without the --skipslave-start option. (Bug #16533802)
• Replication: A slave using row-based replication was unable to read the rows containing columns of
type MYSQL_TYPE_DECIMAL properly (old-style decimal, used prior to MySQL 5.0.3). Now the slave
throws an error if it receives this type of data. You can convert the old-style DECIMAL format to the
binary format used in current MySQL releases with ALTER TABLE; see Upgrading from MySQL 4.1 to
5.0, for more information. (Bug #16416302)
• Replication: DROP TEMP TABLE IF EXISTS statements could lead to failures in applying the
binary log during point-in-time recovery operations. This is due to the fact that, when using row-based
replication, the server appends IF EXISTS to any DROP TEMPORARY TABLE statements written to the
binary log, and that the slave SQL thread does not check * wildcard filter rules for DROP TEMPORARY
TABLE IF EXISTS. If --log-slave-updates was also enabled on the slave, such a statement was
preceded by a USE statement. If the database referred by the USE statement did not exist, the statement
failed, and stopped replication.
Now, when writing DROP TEMPORARY TABLE IF EXISTS into the binary log, no USE statement is
written, and the table name in the DROP TEMPORARY TABLE statement is a fully qualified table name.
(Bug #16290902)
• Savepoints could not be used successfully following an ER_LOCK_DEADLOCK error (or
ER_LOCK_WAIT_TIMEOUT error, if innodb_rollback_on_timeout was enabled). (Bug #17356954)
References: This issue is a regression of: Bug #14188793.
• The mysql_real_connect() C API function could leak memory if it failed. (Bug #17337684)
• Full-text search on InnoDB tables failed on searches that used the + boolean operator. (Bug
#17280122)
• For single-threaded workloads, the optimizer recognizes some special cases for which it can avoid
function calls and enhance performance. (Bug #17234723)
• AES_ENCRYPT() and AES_DECRYPT() failed to work correctly when MySQL was built with an
AES_KEY_LENGTH value of 192 or 256. (Bug #17170207)
• SELECT * from performance_schema.events_statements_current could raise an assertion
due to a race condition under load. (Bug #17164720)
• InnoDB full-text searches failed in databases whose names began with a digit. (Bug #17161372)
• A successful connection failed to reset the per-IP address counter used to count successive connection
failures. This could possibly cause a host to be blocked, when the max_connect_errors limit was
reached. (Bug #17156507)
92
MySQL 5.6 Release Notes
• With the thread pool plugin enabled and SSL in use, an error in one connection might affect other
connections, causing them to experience a lost connection. (Bug #17087862)
• Under load, truncating the accounts Performance Schema table could cause a server exit. (Bug
#17084615)
• Within a stored program, comparison of the value of a scalar subquery with an IN clause resulted in an
error for the first execution and raised an assertion for the second execution. (Bug #17029399)
• The my_strtoll10() function could incorrectly convert some long string-format numbers to numeric
values and fail to set the overflow flag. (Bug #16997513)
• A race condition in the thread pool plugin could cause status variables such as Aborted_connects not
to be incremented and permitting concurrent kills to happen for the same thread ID. (Bug #16959022)
• For partitioned tables, queries could return different results depending on whether Index Merge was
used. (Bug #16862316)
References: See also: Bug #17648468, Bug #176588348, Bug #18167648.
• Excessive memory consumption was observed for multiple execution of a stored procedure under these
circumstances: 1) The stored procedure had an SQL statement that failed during validation. 2) The
stored procedure had an SQL statement that required repreparation. (Bug #16857395)
• For some statements, memory leaks could result when the optimizer removed unneeded subquery
clauses. (Bug #16807641)
References: This issue is a regression of: Bug #15875919.
• Password rewriting in the general query log now also applies to prepared statements. (Bug #16732621)
• Within a stored procedure, repeated execution of a prepared CREATE TABLE statement for a table with
partitions could cause a server exit. (Bug #16614004)
• For debug builds, when the optimizer removed an Item_ref pointing to a subquery, it caused a server
exit. (Bug #16509874)
References: This issue is a regression of: Bug #16318585.
• If the primary key for the mysql.proc system table was removed (an unsupported and notrecommended operation), the server exited for subsequent stored procedure invocation. Similar
problems could occur for other system tables. Now an error occurs instead. (Bug #16373054)
• Deadlocks involving metadata locks and InnoDB deadlocks were both reported as an
ER_LOCK_DEADLOCK error, but only InnoDB deadlocks rolled back the transaction. Now both deadlocks
roll back the transaction. (Bug #14188793)
• Metadata returned for a prepared SELECT statement that had outer joins could indicate that columns
containing NULL values were NOT NULL. (Bug #12818811)
• For queries that accessed an INFORMATION_SCHEMA table in a subquery, an attempt to lock a mutex
that had already been locked could cause a server crash. (Bug #11765744)
• Full-text search on InnoDB tables failed on searches for words containing apostrophes when using
boolean operators.
The innodb_ft_max_token_size maximum value was incorrectly defined as 252, which is the
maximum byte length. The maximum innodb_ft_max_token_size value is now 84, which is the
maximum character length. (Bug #69932, Bug #17276125)
93
MySQL 5.6 Release Notes
• InnoDB deadlock caused transaction rollback but did not release metadata locks, blocking concurrent
DDL on the transaction tables until the connection that got the deadlock issued an explicit COMMIT or
ROLLBACK. (Bug #69668, Bug #17054007)
• The libmysql.dll library was missing several symbols: my_init, mysql_client_find_plugin,
mysql_client_register_plugin, mysql_load_plugin, mysql_load_plugin_v,
mysql_options4, and mysql_plugin_options. (Bug #69204, Bug #16797982, Bug #62394)
• mysqldump wrote SET statements as SET OPTION, which failed when reloaded because the
deprecated OPTION keyword has been removed from SET syntax. (Bug #67507, Bug #15844882)
• For failure to create a new thread for the event scheduler, event execution, or new connection, no
message was written to the error log. This could lead to the impression that the event scheduler was
running normally when it was not. (Bug #67191, Bug #14749800, Bug #16865959)
• If one connection changed its default database and simultaneously another connection executed SHOW
PROCESSLIST, the second connection could access invalid memory when attempting to display the first
connection's default database. memory. (Bug #58198, Bug #11765252)
• For better robustness against stack overflow, the server now accounts for the size of the guard area
when making thread stack size requests. (Bug #35019, Bug #11748074)
Changes in MySQL 5.6.13 (2013-07-31, General Availability)
Known limitations of this release:
Note
On Microsoft Windows, MySQL Installer does not upgrade MySQL Enterprise
Backup (MEB) 3.8.1 to 3.8.2 (latest version). A workaround is to uninstall MEB 3.8.1
and then install MEB 3.8.2 (latest version) with MySQL Installer.
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Functionality Added or Changed
• Bugs Fixed
Functionality Added or Changed
• Incompatible Change: Previously, the Performance Schema statement instrumentation did not
include statements executed on a slave replication server. To address this, a new abstract instrument,
statement/rpl/relay_log, has been added to the setup_instruments table. This instrument
is used during the early stages of replicated statement classification before the exact statement type is
known.
In addition, the statement/com/ abstract statement instrument was renamed to statement/com/
new_packet.
94
MySQL 5.6 Release Notes
Applications that refer to the old instrument names must be updated with the new names. For more
information about the use of abstract instruments in statement classification, see Performance Schema
Statement Event Tables. (Bug #16750433, Bug #17271055)
• Important Change; Replication: By default, when promoting integers from a smaller type on the
master to a larger type on the slave (for example, from a SMALLINT column on the master to a BIGINT
column on the slave), the promoted values are treated as though they are signed. Now in such cases
it is possible to modify or override this behavior using one or both of ALL_SIGNED, ALL_UNSIGNED
in the set of values specified for the slave_type_conversions server system variable. For more
information, see Row-based replication: attribute promotion and demotion, as well as the description of
the variable. (Bug #15831300)
• Previously, program options could be specified in full or as any unambiguous prefix. For example, the
--compress option could be given to mysqldump as --compr, but not as --comp because the latter
is ambiguous. Option prefixes now are deprecated. They can cause problems when new options are
implemented for programs. A prefix that is currently unambiguous might become ambiguous in the
future. If an unambiguous prefix is given, a warning now occurs to provide feedback. For example:
Warning: Using unique option prefix compr instead of compress is
deprecated and will be removed in a future release. Please use the
full name instead.
Option prefixes are no longer supported in MySQL 5.7; only full options are accepted. (Bug #16996656)
• The C API libmysqlclient shared-library .so files now have version 18.1.0 (up from version 18.0.0
used in MySQL 5.5). 18.1.0 can be used as a replacement for 18.0.0. (Bug #16809055, Bug #59106,
Bug #12407476)
• In batch mode, mysql formatted result status messages such as “"Query OK, 1 row affected"” but did
not print them. Now these messages are not formatted. (Bug #69486, Bug #16971432)
Bugs Fixed
• Incompatible Change: It is possible for a column DEFAULT value to be valid for the sql_mode value at
table-creation time but invalid for the sql_mode value when rows are inserted or updated. Example:
SET sql_mode = '';
CREATE TABLE t (d DATE DEFAULT 0);
SET sql_mode = 'NO_ZERO_DATE,STRICT_ALL_TABLES';
INSERT INTO t (d) VALUES(DEFAULT);
In this case, 0 should be accepted for the CREATE TABLE but rejected for the INSERT. However,
previously the server did not evaluate DEFAULT values used for inserts or updates against the current
sql_mode. In the example, the INSERT succeeds and inserts '0000-00-00' into the DATE column.
The server now applies the proper sql_mode checks to generate a warning or error at insert or update
time.
A resulting incompatibility for replication if you use statement-based logging
(binlog_format=STATEMENT) is that if a slave is upgraded, a nonupgraded master will execute the
preceding example without error, whereas the INSERT will fail on the slave and replication will stop.
To deal with this, stop all new statements on the master and wait until the slaves catch up. Then upgrade
the slaves followed by the master. Alternatively, if you cannot stop new statements, temporarily change
to row-based logging on the master (binlog_format=ROW) and wait until all slaves have processed all
95
MySQL 5.6 Release Notes
binary logs produced up to the point of this change. Then upgrade the slaves followed by the master and
change the master back to statement-based logging. (Bug #68041, Bug #16078943)
• Important Change; Performance; InnoDB: InnoDB failed to open a tablespace that has multiple
data files. This removes the known limitation that was in MySQL Server 5.6.12. (Bug #17033706, Bug
#69623)
• Performance; InnoDB: A code regression introduced in MySQL 5.6 negatively impacted DROP TABLE
and ALTER TABLE performance. This could cause a performance drop between MySQL Server 5.5.x
and 5.6.x. (Bug #16864741, Bug #69316)
• Performance; InnoDB: When innodb_thread_concurrency is set to a non-zero value, there was
a possibility that all innodb_concurrency_tickets would be released after each row was read,
resulting in a concurrency check after each read. This could impact performance of all queries. One
symptom could be higher system CPU usage. We strongly recommend that you upgrade to MySQL
Server 5.6.13 if you use this setting. This could cause a performance drop between MySQL Server 5.5.x
and 5.6.x. (Bug #68869, Bug #16622478)
• InnoDB: A full-text search using the IN BOOLEAN MODE modifier would result in an assertion failure.
(Bug #16927092)
References: This issue is a regression of: Bug #16516193.
• InnoDB: When CHECK TABLE found a secondary index that contained the wrong number of entries, it
would report an error but not mark the index as corrupt. CHECK TABLE now marks the index as corrupt
when this error is encountered, but only the index is marked as corrupt, not the table. As a result, only
the index becomes unusable until it is dropped and rebuilt. The table is unaffected. (Bug #16914007)
• InnoDB: InnoDB would attempt to gather statistics on partially created indexes. (Bug #16907783)
• InnoDB: The server would crash during a memcached set operation. The failure was due to a padded
length value for a utf8 CHAR column. During a memcached update operation, a field from an old tuple
would be copied with a data length that was less than the padded utf8 CHAR column value. This fix
ensures that old tuples are not copied. Instead, a new tuple is created each time. (Bug #16875543)
• InnoDB: The two INFORMATION_SCHEMA tables for the InnoDB buffer pool could show an invalid page
type for read-fixed blocks. This fix will show the unknown page type for blocks that are I/O-fixed for
reading. (Bug #16859867)
• InnoDB: Removed invalid compilation warning messages that appeared when compiling the InnoDB
memcached plugin. (Bug #16816824)
• InnoDB: A memory leak would occur when inserting or replacing a row in a full-text search index on a
table with more than 96 columns. (Bug #16809167)
• InnoDB: During an insert buffer merge, InnoDB would invoke
lock_rec_restore_from_page_infimum() on a potentially invalid record pointer. (Bug
#16806366)
• InnoDB: The innodb_rwlock_x_spin_waits item in the
INFORMATION_SCHEMA.INNODB_METRICS table would show the same value as the
innodb_rwlock_x_os_waits item. (Bug #16798175)
• InnoDB: In debug builds, an assertion could occur in OPT_CHECK_ORDER_BY when using binary directly
in a search string, as binary may include NULL bytes and other non-meaningful characters. This fix will
remove non-meaningful characters before the search is run. (Bug #16766016)
96
MySQL 5.6 Release Notes
• InnoDB: Valgrind testing returned memory leak errors which resulted from a regression introduced by
the fix for Bug #11753153. The dict_create_add_foreign_to_dictionary function would call
pars_info_create but failed to call pars_info_free. (Bug #16754901)
• InnoDB: The page_zip_validate() consistency check failed after compressing a page, in
page_zip_compress(). This problem was caused by page_zip_decompress(), which failed to set
heap_no correctly when a record contained no user data bytes. A record with no user data bytes occurs
when, for example, a primary key is an empty string and all secondary index fields are NULL or an empty
string. (Bug #16736929)
• InnoDB: Some characters in the identifier for a foreign key constraint are modified during table exports.
(Bug #16722314, Bug #69062)
• InnoDB: Stale InnoDB memcached connections would result in a memory leak. (Bug #16707516, Bug
#68530)
• InnoDB: A race condition would occur between ALTER TABLE ... ADD KEY and INSERT statements,
resulting in an “Unable to Purge a Record” error. (Bug #16628233)
• InnoDB: Very large InnoDB full-text search (FTS) results could consume an excessive amount of
memory. This bug fix reduces memory consumption for FTS results and introduces a new configuration
parameter, innodb_ft_result_cache_limit, which places a default size limit of 2000000000
bytes on the InnoDB FTS query result cache. innodb_ft_result_cache_limit has an unlimited
maximum value and can be set dynamically. (Bug #16625973)
• InnoDB: During a transaction commit, prepare_commit_mutex is acquired to preserve the commit
order. If the commit operation failed, the transaction would be rolled back but the mutex would not be
released. Subsequent insert operations would not be able to acquire the same mutex. This fix frees
prepare_commit_mutex during innobase_rollback. (Bug #16513588)
• InnoDB: When the InnoDB shutdown mode (innodb_fast_shutdown) is set to 2 and the master
thread enters the flush loop, the thread would not be able to exit under some circumstances. This could
lead to a shutdown hang. (Bug #16411457)
• InnoDB: Restarting InnoDB in read-only mode and running a workload would occasionally return a
global_segment < os_aio_n_segments assertion. (Bug #16362046)
• InnoDB: While printing a UTF-8 table name, InnoDB would truncate the table name, resulting in an
incomplete buffer and subsequent Valgrind error. This bug fix also addresses an incorrect debugging
error message. (Bug #16066351)
• InnoDB: Attempting to create a table while in innodb_read_only mode resulted in the following error:
ERROR 1015 (HY000): Can't lock file (errno: 165 - Table is read only). (Bug
#15963619)
• InnoDB: Creating numerous tables, each with a full-text search index, could result in excessive memory
consumption. This bug fix adds a new configuration parameter, innodb_ft_total_cache_size,
which defines a global memory limit for full-text search indexes. If the global limit is reached by an index
operation, a force sync is triggered. (Bug #14834698, Bug #16817453)
• InnoDB: In the error log, a full-text search index would be reported missing from the data dictionary
during a TRUNCATE TABLE operation. After restarting mysqld, the following InnoDB error would be
reported: “InnoDB: Error: trying to load index idx13 for table test/g1 but the
index tree has been freed..” (Bug #12429565)
References: See also: Bug #17402002.
97
MySQL 5.6 Release Notes
• InnoDB: The row_check_index_for_mysql method, which checks for NULL fields during an index
scan or CHECK TABLE operation, would iterate unnecessarily. Thanks to Po-Chun Chang for the patch
to correct this issue. (Bug #69377, Bug #16896647)
• InnoDB: When running an InnoDB full-text search in boolean mode, prefixing an asterisk (*) to a search
string ('*string') would result in an error whereas for MyISAM, a prefixed asterisk would be ignored.
To ensure compatibility between InnoDB and MyISAM, InnoDB now handles a prefixed asterisk in the
same way as MyISAM. (Bug #68948, Bug #16660607)
• InnoDB: Successive deletes in descending key order would lead to under-filled InnoDB index pages.
When an InnoDB index page is under-filled, it is merged with the left or right sibling node. The check
performed to determine if a sibling node is available for merging was not functioning correctly. (Bug
#68501, Bug #16417635)
• InnoDB: Setting foreign_key_checks=0 and running ALTER TABLE to change the character set
of foreign key columns for a database with multiple tables with foreign key constraints would leave the
database in an inconsistent state. Subsequent ALTER TABLE operations (using the COPY algorithm)
with foreign_key_checks=1 would fail due to the detected inconsistency. Reversion of the partially
executed ALTER TABLE operation would also fail, resulting in the loss of the table being altered. When
running the same ALTER TABLE operation with a RENAME clause, the inconsistency would not be
detected but if the ALTER TABLE operation failed for some other reason, reversion of the partially
executed ALTER TABLE failed with the same result.
The bug fix temporarily disables foreign_key_checks while the previous table definition is restored.
(Bug #65701, Bug #14227431)
• InnoDB: Creating a table with a comment or default textual value containing an apostrophe that is
escaped with a backslash would sometimes cause the InnoDB storage engine to omit foreign key
definitions. (Bug #61656, Bug #12762377)
• InnoDB: The pthread_mutex, commit_threads_m, which was initialized but never used, has been
removed from the code base. (Bug #60225, Bug #11829813)
• Partitioning: When upgrading to MySQL 5.5.31 or higher, a message is written into the output of
mysql_upgrade when encountering a partitioned table for which the ALGORITHM option is required
to maintain binary compatibility with the original; the message includes the ALTER TABLE statement
required to make the change. For such a table having a sufficiently large number of partitions, the
message was truncated with an error before the complete ALTER TABLE statement could be written.
(Bug #16589511)
• Partitioning: When a range was specified in the WHERE condition of a query against a table partitioned
by range, and the specified range was entirely within one of the partitions, the next partition was also
checked for rows although it should have been pruned away.
Suppose we have a range-partitioned table t created using the following SQL statement:
CREATE TABLE t (
id INT AUTO_INCREMENT,
dt DATETIME,
PRIMARY KEY (dt,id),
UNIQUE KEY (id,dt)
)
PARTITION BY RANGE COLUMNS(dt) (
PARTITION p0 VALUES LESS THAN ('2013-01-01'),
PARTITION p1 VALUES LESS THAN ('2013-01-15'),
PARTITION p2 VALUES LESS THAN ('2013-02-01'),
PARTITION p3 VALUES LESS THAN ('2013-02-15'),
PARTITION pmax VALUES LESS THAN (MAXVALUE)
98
MySQL 5.6 Release Notes
);
An example of a query that exhibited this issue when run against t is shown here:
SELECT COUNT(*) FROM t
WHERE dt >= '2013-02-01' AND dt < '2013-02-15';
In this case, partition pmax was checked, even though the range given in the WHERE clause lay entirely
within partition p3. (Bug #16447483)
• Partitioning: When dropping a partitioned table, the table's .par file was deleted first, before the table
definition or data. This meant that, if the server failed during the drop operation, the table could be left in
an inconsistent state in which it could neither be accessed nor dropped.
The fix for this problem makes the following changes:
• Now, when dropping a partitioned table, the table's .par file is not removed until all table data has
been deleted.
• When executing DROP TABLE of a partitioned table, in the event that its .par file is determined to be
missing, the table's .frm file is now immediately deleted, in effect forcing the drop to complete.
(Bug #13548704, Bug #63884)
• Replication: The condition leading to the issue fixed in Bug #16579083 continued to raise an error even
though the condition itself no longer cause the issue to occur. (Bug #16931177, Bug #69369)
References: See also: Bug #16271657, Bug #16491597, Bug #68251, Bug #68569. This issue is a
regression of: Bug #16579083.
• Replication: When rpl_semi_sync_master_timeout was set to an extremely large value,
semisynchronous replication became very slow, especially when many sessions were working in
parallel. It was discovered that the code to calculate this timeout was inside the wait loop itself, with the
result that an increase in the value of rpl_semi_sync_master_timeout caused repeated iterations.
This fix improves the method used to calculate wakeup times, and moves it outside of the wait loop, so
that it is executed one time only. (Bug #16878043, Bug #69341)
• Replication: It was possible to cause a deadlock after issuing FLUSH TABLES WITH READ LOCK by
issuing STOP SLAVE in a new connection to the slave, then issuing SHOW SLAVE STATUS using the
original connection.
The fix for this includes the addition of the rpl_stop_slave_timeout system variable, to control the
time in seconds to wait for slave to stop after issuing STOP SLAVE before returning a warning. (Bug
#16856735)
• Replication: Some expressions employing variables were not handled correctly by LOAD DATA. (Bug
#16753869)
• Replication: In some circumstances, the message in the Last_Error column from the output of SHOW
SLAVE STATUS referred to GTID_NEXT_LIST although this variable is not currently implemented (the
name is reserved for possible future use). Now in such cases the error message no longer refers to this
variable. (Bug #16742886, Bug #69096)
References: See also: Bug #16715809, Bug #69045.
• Replication: Linker errors occurred if the header file log_event.h was included in an application
containing multiple source files, because the file rpl_tblmap.cc was included in log_event.h.
99
MySQL 5.6 Release Notes
This fix moves the inclusion of rpl_tblmap.cc into the source files that use log_event.h. (Bug
#16607258)
• Replication: The error displayed by SHOW SLAVE STATUS when a worker thread fails to apply an event
contained no event coordinate information. The GTID for the event's group was also not shown. Now
in such cases, the text shown for Last_SQL_Error is prefixed with the (physical) master binary log
coordinates, as well as the value of gtid_next when this has been set. (Bug #16594095)
• Replication: The warning issued when specifying MASTER_USER or MASTER_PASSWORD with CHANGE
MASTER TO was unclear for a number of reasons, and has been changed to read, Storing MySQL
user name or password information in the master info repository is not secure
and is therefore not recommended. Please consider using the USER and PASSWORD
connection options for START SLAVE; see 'START SLAVE Syntax' in the MySQL
Manual for more information. (Bug #16460123, Bug #16461303, Bug #68602, Bug #68599)
• Replication: After a transaction was skipped due to its GTID already having been logged, all remaining
executed transactions were incorrectly skipped until gtid_next was pointed to a different GTID.
To avoid this incorrect behavior, all transactions—even those that have been skipped—are marked
as undefined when they are commited or rolled back, so that an error is thrown whenever a second
transaction is executed following the same SET @@session.gtid_next statement. (Bug #16223835)
• Replication: After the client thread on a slave performed a FLUSH TABLES WITH READ LOCK and
was followed by some updates on the master, the slave hung when executing SHOW SLAVE STATUS.
(Bug #68460, Bug #16387720)
• The optimizer failed to check a function return value for an area calculation, leading to a server exit. (Bug
#23280059)
• Reads from message buffers for closed connections could occur. (Bug #17003702)
• The server could exit while using a cursor to fetch rows from a UNION query. (Bug #16983143)
• Sql_condition::set_subclass_origin() could perform an out-of-bounds read. (Bug #16969091)
• The range optimizer incorrectly assumed that any geometry function on a spatial index returned rows in
ROWID order, which could result in incorrect query results. (Bug #16960800)
• Initialization of keycache_* variables (see Multiple Key Caches) during server startup could write to
incorrect memory. (Bug #16945503)
• For debug builds, improper use of SAFE_MUTEX within dbug.c caused different code areas to have
different ideas about size and contents of a mutex. This could result in out-of-bounds memory writes.
(Bug #16945343)
• The Performance Schema could spawn a thread using incorrect instrumentation information. (Bug
#16939689)
• The server did excessive locking on the LOCK_active_mi and active_mi->rli->data_lock
mutexes for any SHOW STATUS LIKE 'pattern' statement, even when the pattern did not match
status variables that use those mutexes (Slave_heartbeat_period, Slave_last_heartbeat,
Slave_received_heartbeats, Slave_retried_transactions, Slave_running). Now
attempts to show those variables do not lock those mutexes. This might result is slightly stale data, but
better performance. (Bug #16904035)
• Full-text phrase search in InnoDB tables could read incorrect memory. (Bug #16885178)
• It was not possible to keep several major versions of MySQL in the same yum repository. (Bug
#16878042)
100
MySQL 5.6 Release Notes
• INSERT ... ON DUPLICATE KEY UPDATE could cause a server exit if a column with no default value
was set to DEFAULT. (Bug #16756402)
References: This issue is a regression of: Bug #14789787.
• In a prepared statement or stored routine, if the HAVING clause of a subquery referenced some column
of the GROUP BY of the parent query, the server could exit. (Bug #16739050)
• Compiling failed with -DMY_ATOMIC_MODE_RWLOCKS=1 or on platforms on which MySQL did not
support lockless atomic operations (such as ARM). (Bug #16736461)
• The code base was modified to account for new warning checks introduced by gcc 4.8. (Bug
#16729109)
• The read-only open_files_limit system variable did not show the maximum number of open files
the mysqld process could have, but instead the number that was requested after adjusting the --openfiles-limit command-line option. (Bug #16657588)
• The server could make the wrong decision about whether an account password was expired. (Bug
#16604641)
• Some rows for a session could be missing sporadically from the session_connect_attrs
Performance Schema table while the session was executing a workload. (Bug #16576980)
• Upgrading from community SLES RPM packages to commercial packages for the same MySQL version
failed with conflict errors. (Bug #16545296)
• If the optimizer was using a loose index scan, the server could exit while attempting to create a
temporary table. (Bug #16436567)
• Incorrect results or a server exit could be caused by a reference to an aggregated expression inside a
nested subquery, where the aggregated expression was evaluated in a query block more than two levels
outer to the reference. (Bug #16436383)
• Unlike MyISAM, InnoDB does not support boolean full-text searches on nonindexed columns, but this
restriction was not enforced, resulting in queries that returned incorrect results. (Bug #16434374)
• A full-text search syntax error failed to print to standard output. (Bug #16429688, Bug #16765397)
• A server exit could occur for queries of the form SELECT (SELECT 1 FROM t1) IN (SELECT a
FROM t1) when attempting to evaluate the constant left-hand argument to the IN subquery predicate.
(Bug #16369522)
• An assertion could be raised when creating a index on a prefix of a TINYBLOB or GEOMETRY column in
an InnoDB column. (Bug #16368875, Bug #18776592, Bug #17665767)
• In debug builds, failure in the range optimizer for an ER_LOCK_DEADLOCK or ER_LOCK_WAIT_TIMEOUT
error could go undetected and cause an assertion to be raised when a response was sent to the client.
In release builds, this problem manifested as clients receiving an OK for a statement that had failed. (Bug
#16366994, Bug #16247110)
• Transforming some subqueries that select temporal or BIGINT types or to a semijoin caused a server
exit on the second execution of prepared statements or stored programs. (Bug #16319671)
• The server could exit in do_copy_not_null() due to an improper NULL-value check. (Bug
#16316564)
• No warning was generated if a duplicate index existed after dropping a column associated with a
multiple-column index. (Bug #16315351)
101
MySQL 5.6 Release Notes
• SELECT DISTINCT with WITH ROLLUP could result in a Duplicate entry 'NULL' for key
'<auto_key>' error. (Bug #16314835)
• The usual failed-login attempt accounting was not applied to failed COM_CHANGE_USER commands. (Bug
#16241992, Bug #17357535)
• A user variable referenced during execution of a prepared statement is set to memory that is freed at the
end of execution. A second execution of the statement could result in Valgrind warnings when accessing
this memory. (Bug #16119355)
• Misoptimization of left expressions in prepared statements could cause a server exit. (Bug #16095534)
• The optimizer trace could print ranges for key parts that were not usable for range access. (Bug
#14615536)
• Passwords in statements were not obfuscated before being written to the audit log. (Bug #14536456)
• When running a query on INFORMATION_SCHEMA.INNODB_BUFFER_PAGE that requested
table_name and index_name values, query results would include index pages without table_name
or index_name values. (Bug #14529666)
• Several COM_xxx commands in the client-server protocol did not have length checks for incoming
network packets, which could result in various problems for malformed input. (Bug #14525642)
• With the thread pool plugin in use, normal connection termination caused the Aborted_clients status
variable to be incremented. (Bug #14081240)
• On Windows, command-line options of the form --opt_name="opt_value" worked but
--opt_name='opt_value' did not.
On all platforms, for Performance Schema options of the form -performance_schema_instrument="instrument=value", invalid instrument names now are
rejected. (Bug #13955232)
• MySQL Installer, if run in custom install or change mode, offered installation options that had no effect.
(Bug #12928601)
• Incorrect results could be returned from queries that used several aggr_func(DISTINCT) functions
(where aggr_func() is an aggregate function such as COUNT()) when these referred to different
columns of the same composite key. (Bug #12328597)
• RPM packages did not provide lowercase tags for their contents. For example, a server RPM indicated
that it provided MySQL-server, but not mysql-server. (Bug #69830, Bug #17211588)
• When selecting a union of an empty result set (created with WHERE 1=0 or WHERE FALSE) with a
derived table, incorrect filtering was applied to the derived table. (Bug #69471, Bug #16961803)
References: This issue is a regression of: Bug #15848521.
• For queries with ORDER BY ... LIMIT, the optimizer could choose a nonordering index for table
access. (Bug #69410, Bug #16916596)
• When an internal buffer was too small for the workload, the Performance Schema could spend a lot
of time in an internal spin loop attempting to allocate a memory buffer, and fail. (Bug #69382, Bug
#16945618)
• In the absence of SQL_CALC_FOUND_ROWS in the preceding query, FOUND_ROWS() should return the
number of rows in the result set, but this did not always happen if the query contained ORDER BY. (Bug
#69271, Bug #16827872)
102
MySQL 5.6 Release Notes
• Full-text search on InnoDB tables failed on searches for words containing apostrophes. (Bug #69216,
Bug #16801781)
• If an UPDATE containing a subquery caused a deadlock inside InnoDB, the deadlock was not properly
handled by the SQL layer. The SQL layer then tried to unlock the row after InnoDB rolled back the
transaction, raising an assertion inside InnoDB. (Bug #69127, Bug #16757869)
• Some LEFT JOIN queries with GROUP BY could return incorrect results. (Bug #68897, Bug #16620047)
References: This issue is a regression of: Bug #11760517.
• Comparison of a DATETIME value and a string did not work correctly for the utf8_unicode_ci
collation. (Bug #68795, Bug #16567381)
• Full-text search on InnoDB tables failed on searches for literal phrases combined with + or - operators.
(Bug #68720, Bug #16516193)
• Optimizations that used extended secondary keys (see Use of Index Extensions) worked only for
InnoDB, even for storage engines with the requisite underlying capabilities. (Bug #68469, Bug
#16391678)
• mysql_install_db incorrectly tried to create the mysql.innodb_table_stats and
mysql.innodb_index_stats tables if InnoDB was not available. (Bug #68438, Bug #16369955)
• mysqldump assumed the existence of the general_log and slow_log tables in the mysql database.
It failed if invoked to dump tables from an older server where these tables do not exist. (Bug #65670,
Bug #14236170)
• Attempts to build from a source RPM package could fail because the build process attempted to refer to
a pb2user that might not exist. (Bug #64641, Bug #13865797, Bug #69339, Bug #16874980)
• If one session had any metadata lock on a table, another session attempting CREATE TABLE [IF
NOT EXISTS] for the same table would hang. This occurred due to an attempt in the second session
to acquire an exclusive metadata lock on the table before checking whether the table already existed.
An exclusive metadata lock is not compatible with any other metadata locks, so the session hung for the
lock timeout period if another session had the table locked.
Now the server attempts to acquire a shared metadata lock on the table first to check whether it exists,
then upgrade to an exclusive lock if it does not. If the table does exist, an error occurs for CREATE
TABLE and a warning for CREATE TABLE IF NOT EXISTS. (Bug #63144, Bug #13418638)
• sql-common/client_plugin.c contained a nonportable use of a va_list parameter. (Bug #62769,
Bug #13252623)
• Unoptimized versions of the xxxkorr() macros in my_global.h were used on 64-bit x86 processors.
(Bug #61179, Bug #12565703)
• A typo in cmake/dtrace.cmake prevented DTrace support from being enabled by DENABLE_DTRACE-on. (Bug #60743, Bug #12325449)
• Boolean plugin system variables did not behave well on machines where char is unsigned; some code
attempted to assign a negative value to these. (Bug #59905, Bug #11864205)
• With big_tables enabled, queries that used COUNT(DISTINCT) on a simple join with a constant
equality condition on a non-duplicate key returned incorrect results. (Bug #52582, Bug #11760197)
References: See also: Bug #18853696.
103
MySQL 5.6 Release Notes
Changes in MySQL 5.6.12 (2013-06-03, General Availability)
Known limitations of this release:
Important
InnoDB may fail to open a tablespace that has multiple data files due to newly
introduced corruption checking functionality. It is recommended that you do not
upgrade to this version if you have more than one file for your shared InnoDB
tablespace. If you have upgraded to an affected version and the server no longer
starts, you can upgrade to a later version when it becomes available or downgrade
to an earlier version.
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• Functionality Added or Changed
• Bugs Fixed
Functionality Added or Changed
• mysql_upgrade now verifies that the server version matches the version against which it was
compiled, and exits if there is a mismatch. In addiion, a --version-check option permits specifying
whether to enable version checking (the default), or disable checking if given as --skip-versionchecking. (Bug #16500013)
Bugs Fixed
• Incompatible Change: When used for an existing MySQL account, the GRANT statement could produce
unexpected results if it included an IDENTIFIED WITH clause that named an authentication plug
differing from the plugin named in the corresponding mysql.user table row.
Because IDENTIFIED WITH is intended only for GRANT statements that create a new user, it is now
prohibited if the named account already exists. (Bug #16083276)
• Important Change; Replication: When the server was running with --binlog-ignore-db and
SELECT DATABASE() returned NULL (that is, there was no currently selected database), statements
using fully qualified table names in dbname.tblname format were not written to the binary log. This was
because the lack of a currently selected database in such cases was treated as a match for any possible
ignore option rather than for no such option; this meant that these statements were always ignored.
Now, if there is no current database, a statement using fully qualified table names is always written to the
binary log. (Bug #11829838, Bug #60188)
• InnoDB; Partitioning: Joins involving partitioned InnoDB tables having one or more BLOB columns
were not always handled correctly. The BLOB column or columns were not required to be join columns,
or otherwise to be named or referenced in the statement containing the join, for this issue to occur. (Bug
#16367691)
• InnoDB: In debug builds, an online ALTER TABLE operation that performed a full table copy would
raise an assertion. The assertion was due to a race condition that would occur during BLOB retrieval,
104
MySQL 5.6 Release Notes
when applying the table modification log to any log block except for the very last one. This fix modifies
row_log_table_apply_convert_mrec() to ensure that an index B-tree lock is acquired to protect
the access to log->blobs and the BLOB page. (Bug #16774118)
• InnoDB: When the function trx_rollback_or_clean_recovered() rolls back or cleans
up transactions during a crash recovery, it removes the trx objects from the trx_sys list
without freeing up the memory used by those objects. To prevent a memory leak, this fix adds
trx_free_for_background() calls to trx_rollback_resurrected(), the function that removes
the trx objects. (Bug #16754776)
• InnoDB: A memory leak would occur in dict_check_tablespaces_and_store_max_id() when
space_id is equal to zero. (Bug #16737332)
• InnoDB: A missing comma in SHOW STATUS output would break MySQL Enterprise Monitor parsing.
(Bug #16723686)
• InnoDB: After a clean shutdown, InnoDB does not check .ibd file headers at startup. As a result, in a
crash recovery scenario, InnoDB could load a corrupted tablespace file. This fix implements consistency
and status checks to avoid loading corrupted files. (Bug #16720368)
• InnoDB: This fix addresses a race condition that would occur between the rollback of a recovered
transaction and creation of a secondary index in a locked operation. The race condition would corrupt
the secondary index. (Bug #16593427)
• InnoDB: DML operations on compressed temporary tables would result in a Valgrind error in the buffer
manager stack. (Bug #16593331)
• InnoDB: For ALTER TABLE operations on InnoDB tables that required a table-copying operation,
other transactions on the table might fail during the copy. However, if such a transaction issued a partial
rollback, the rollback was treated as a full rollback. (Bug #16544143)
• InnoDB: The recv_writer thread would only start after all redo log scans finished. In the case
of multiple redo log scans, accumulated redo records would be applied after each scan and before
processing the next scan. The absence of the recv_writer thread to help with flushing would slow
recovery or result in a server startup timeout. This fix ensures that the recv_writer thread starts
before the first scan batch is processed. (Bug #16501172)
• InnoDB: Under certain circumstances, LRU flushing would take a long time possibly affecting all flushing
activity and causing a shutdown timeout. (Bug #16500209)
• InnoDB: The InnoDB memcached test.demo_test table failed to work when defined as a utf8
charset table. (Bug #16499038)
• InnoDB: In cases where threads are forced to do single page flushing, fsync() would be triggered for
all data files. This fix allows for synchronous single page flushing. (Bug #16477781)
• InnoDB: This fix removes most calls to OS_THREAD_SLEEP from InnoDB. (Bug #16472953, Bug
#68588)
• InnoDB: FLUSH TABLES ... FOR EXPORT slept too often while flushing pages from buffer pools.
(Bug #16471701)
• InnoDB: Concurrently inserting into a full-text table would cause some inserts to fail. Duplicate values
would be generated for full-text search document IDs when performing inserts into a hidden full-text
search document ID column. (Bug #16469399)
• InnoDB: The page_zip_available function would count some fields twice. (Bug #16463505)
105
MySQL 5.6 Release Notes
• InnoDB: This fix replaces the IB_ULONGLONG_MAX constant with LSN_MAX where the code refers to
log sequence numbers, or with TRX_ID_MAX where trx->no is initialized to an undefined value. This
change does not alter the value of the constant. (Bug #16458660)
• InnoDB: This fix corrects the text for InnoDB error 6025, which stated, “InnoDB: read can't be opened
in ./ib_logfile0 mode.”. The corrected message states, “InnoDB: ./ib_logfile0 can't be opened in read
mode.” The variable and mode in the message construct were transposed. (Bug #16434398)
• InnoDB: Creating a foreign key constraint using the ALTER TABLE INPLACE algorithm requires
foreign_key_checks to be set to 0 (SET foreign_key_checks = 0;). As a result, an appropriate
duplicate ID check would not be performed. (Bug #16413976)
• InnoDB: In debug builds, an insert failed with an invalid assertion: sync_thread_levels_g(array,
level - 1, TRUE). (Bug #16409715)
• InnoDB: Multiple concurrent calls to dict_update_statistics() would result in unnecessary server
load. (Bug #16400412)
• InnoDB: On 64-bit Windows builds, INNODB_BUFFER_POOL_SIZE would not accept an allocation of
more than 32GB. This limitation was due to a bug that truncated the internal value for the InnoDB buffer
pool size to 32 bits on 64-bit Windows builds. (Bug #16391722, Bug #68470)
• InnoDB: DROP DATABASE failed if the database contained an InnoDB table that had a data file in an
external data directory. The external data file had an “InnoDB Symbolic Link” file type (.isl) that was
not recognized by MySQL. This fix adds .isl as a known InnoDB file type. (Bug #16338667)
• InnoDB: RENAME TABLE would result in a hang due to a MySQL mutex acquisition deadlock. (Bug
#16305265)
• InnoDB: Under testing, a FLUSH TABLES operation resulted in a timeout due to a missing
acknowledgment that the purge thread had stopped. (Bug #16277387)
• InnoDB: For compressed tables, a page reorganize operation would always write
an MLOG_ZIP_PAGE_REORGANIZE record to the redo log, which is only correct if
innodb_log_compressed_pages=OFF. When innodb_log_compressed_pages=ON, the page
reorganize operation should log the compressed page image. (Bug #16267120)
• InnoDB: When tables are linked by foreign key constraints, loading one table would open other linked
tables recursively. When numerous tables are linked by foreign key constraints, this would sometimes
lead to a thread stack overflow causing the server to exit. Tables linked by foreign key constraints are
now loaded iteratively. Cascade operations, which were also performed in a recursive manner, are now
performed iteratively using an explicit stack. (Bug #16244691, Bug #65384)
• InnoDB: After disabling foreign key checks with SET foreign_key_checks=0 and performing a
DROP INDEX, the table was no longer accessible after restarting the server. This fix allows the table
with missing foreign key indexes to be accessed when SET foreign_key_checks=0. When the
table is accessible, the user must recreate the missing indexes to fulfill the foreign key constraints. (Bug
#16208542, Bug #68148)
• InnoDB: When a transaction is in READ COMMITTED isolation level, gap locks are still taken in
the secondary index when a row is inserted. This occurs when the secondary index is scanned
for duplicates. The function row_ins_scan_sec_index_for_duplicate() always calls the
function row_ins_set_shared_rec_lock() with LOCK_ORDINARY irrespective of the transaction
isolation level. This fix modifies the row_ins_scan_sec_index_for_duplicate() function to call
row_ins_set_shared_rec_lock() with LOCK_ORDINARY or LOCK_REC_NOT_GAP, based on the
transaction isolation level. (Bug #16133801, Bug #68021)
106
MySQL 5.6 Release Notes
• InnoDB: Starting mysqld with --innodb_log_buffer_size=50GB failed to allocate memory and
returned NULL. For non-debug builds there was no check in place and a segmentation fault occurred.
This fix adds a log message stating that memory failed to be allocated, and adds an assertion. (Bug
#16069598, Bug #68025)
• InnoDB: When UNIV_DEBUG is enabled in debug builds, buf_validate() is often called which
sometimes results in false alarms in tests on semaphore wait timeout. This fix increases counter values
to reduce false alarms. (Bug #16068056)
• InnoDB: The explain_filename function, which provides information about a partition by parsing the
file name, would return an error when attempting to parse a file name with no partition information. (Bug
#16051728)
• InnoDB: Stopping the server, removing a database table (d1.t1) .frm file from the data directory,
restarting the server, and dropping the database (d1), would cause an assertion. (Bug #16043216)
• InnoDB: While processing read-write workloads, InnoDB would scan more pages than are required for
flushing, unnecessarily consuming CPU resource. (Bug #16037180)
• InnoDB: An active FLUSH TABLES ... FOR EXPORT thread would cause a hang during shutdown.
The fix ensures that trx_is_interrupted() is checked during ibuf_merge. (Bug #15953255)
• InnoDB: A multi-row INSERT ... ON DUPLICATE KEY UPDATE insert failure, caused by a duplicate
key error, would result in duplicate auto-increment values. (Bug #14483484, Bug #66301)
• Replication: Issuing a FLUSH TABLES statement on a GTID-enabled master caused replication to
fail. It was found that this misbehavior was introduced by the fix for Bug #16062608, which disallowed
statements that perform an implicit commit but whose changes are not logged when gtid_next is
set to any value other than AUTOMATIC. The changes made in that fix have been reverted, and such
statements are (again) allowed without regard to the value of this variable. (Bug #16715809, Bug
#69045)
References: Reverted patches: Bug #16062608.
• Replication: Point-in-time recovery could fail when trying to restore a single database from a binary log
in row-based format using mysqlbinlog with the --database option. (Bug #16698172)
• Replication: A crash-on-commit error caused InnoDB to lose the previous transaction following
execution of a RESET MASTER statement. This occurred because the prepare phase caused a flush to
disk, while the commit phase did not perform a corresponding flush within InnoDB.
To fix this problem, RESET MASTER now causes storage engine logs to be flushed on commit. (Bug
#16666456, Bug #68932)
• Replication: When processing an Update_rows_log_event or Delete_rows_log_event from
the binary log, the before image is hashed and stored in a hash table. Following this, the original
table is scanned for the desired records; subsequent processing hashes each record fetched from the
original table and performs a lookup for it in the hash table. However, columns read from the image that
had originally been set to NULL could instead contain random or “garbage” data, causing the lookup
(and thus replication) to fail with an error such as Could not execute Update_rows event on
table.... (Bug #16621923)
References: See also: Bug #11766865. This issue is a regression of: Bug #16566658.
• Replication: When used with the options --dump-slave --include-master-host-port,
mysqldump printed the port number within quotation marks, as if it were a string value rather than an
integer. (Bug #16615117)
107
MySQL 5.6 Release Notes
• Replication: Due to time resolution issues on some systems, the time to be taken by the dump
thread for a reply from the slave could be calculated to be less than zero, leading to Semi-sync
master wait for reply fail to get wait time errors. Since this condition does not have a
negative impact on replication, errors caused by these conditions have been reduced to warnings. (Bug
#16579028)
• Replication: Trying to update a column, previously set to NULL, of a table with no primary key caused
replication to fail with Can't find record in 'table'....
This issue was originally fixed in MySQL 5.6.3 but was inadvertently reintroduced in MySQL 5.6.6. (Bug
#16566658)
References: See also: Bug #16621923. This issue is a regression of: Bug #11766865.
• Replication: Running the server with --log-slave-updates together with --replicate-wildignore-table or --replicate-ignore-table in some cases caused updates to user variables not
to be logged. (Bug #16541422)
• Replication: When using mysqlbinlog and the mysql client to roll forward two or more binary logs on
a server having GTIDs enabled, the gtid_next variable was not properly reset when switching from the
first to the second binary log, causing processing to halt with an error at that point. (Bug #16532543)
• Replication: The mysqlbinlog options --include-gtids, --exclude-gtids, and --skipgtids did not work correctly when trying to process multiple files. (Bug #16517775)
• Replication: When one or more GTID log events but no previous GTIDs log events were found in the
binary log, the resulting error was mishandled and led to a failure of the server. (This is an extremely rare
condition that should never occur under normal circumstances, and likely indicates that the binary log
file has somehow been corrupted.) Now in such cases, an appropriate error is issued, and is handled
correctly. (Bug #16502579, Bug #68638)
• Replication: Attempting to execute START SLAVE after importing new slave_master_info and
slave_relay_log_info tables failed with an empty error message. Now an appropriate error and
message are issued in such cases. (Bug #16475866, Bug #68605)
• Replication: Restarting the server after the slave_relay_log_info table had been emptied caused
mysqld to fail while trying to return an error. (Bug #16460978, Bug #68604)
• Replication: Extra binary log rotations were performed due to concurrent attempts at rotation when the
binary log became full, which were allowed to succeed. This could lead to the unnecessary creation of
many small binary log files. (Bug #16443676, Bug #68575)
• Replication: When the size of an execution event exceeded the maximum set for the buffer
(slave_pending_jobs_size_max), row-based replication could hang with Waiting for slave
workers to free pending events. (Bug #16439245, Bug #68462)
• Replication: Following disconnection from the master, the slave could under certain conditions
report erroneously on reconnection that it had received a packet that was larger than
slave_max_allowed_packet, causing replication to fail. (Bug #16438800, Bug #68490)
• Replication: An SQL thread error during MTS slave recovery caused the slave to fail. (Bug #16407467,
Bug #68506)
• Replication: When using the options --read-from-remote-server --stop-never --base64output=decode-rows --verbose, mysqlbinlog failed to reset the counter used to store the current
position within the file when the binary log on the server was rotated. (Bug #16316123, Bug #68347)
108
MySQL 5.6 Release Notes
• Replication: When using mysqldump to back up a database created with MySQL 5.6.4 or an earlier
version, setting --set-gtid-purged=AUTO caused the backup to fail, because pre-5.6.5 versions of
MySQL did not support GTIDs, and it could not be determined if GTIDs were enabled for the database.
This fix makes sure mysqldump does not attempt to output a SET @@global.gtid_purged statement
when backing up any pre-5.6.5 databases. (Bug #16303363, Bug #68314)
• Replication: Deadlocks could sometimes occur on group commits with a high number of concurrent
updates, as well as when one client held a lock from a commit while another client imposed a lock while
rotating the binary log. (Bug #16271657, Bug #16491597, Bug #68251, Bug #68569)
• Replication: When semisynchronous replication was enabled, the automatic dropping on the master of
an event created using ON COMPLETION NOT PRESERVE caused the master to fail. (Bug #15948818,
Bug #67276)
• Replication: Setting a SET column to NULL inside a stored procedure caused replication to fail. (Bug
#14593883, Bug #66637)
• Replication: The binary log contents got corrupted sometimes, because the function
MYSQL_BIN_LOG::write_cache always thought it had reached the end-of-cache when the function
my_b_fill() reported a '0,' while that could also mean an error had occurred. This fix makes sure that
whenever my_b_fill() returns a '0,' an error check is performed on info->error. (Bug #14324766,
Bug #60173)
• Replication: PURGE BINARY LOGS by design does not remove binary log files that are in use or active,
but did not provide any notice when this occurred. Now, when log files are not removed under such
conditions, a warning is issued; this warning includes information about the file or files were not removed
when the statement was issued. (Bug #13727933, Bug #63138)
• Replication: When replicating to a BLACKHOLE table using the binary logging format, updates and
deletes cannot be applied and so are skipped. Now a warning is generated for this whenever it occurs.
Note
binlog_format=STATEMENT is recommended when replicating to tables that
use the BLACKHOLE storage engine.
(Bug #13004581)
• Removing a server RPM package did not shut down the existing server if it was running. (Bug
#16798868)
• Overhead for setting PROCESSLIST_STATE values in the THREADS Performance Schema table has
been reduced. (Bug #16633515)
• The Windows authentication plugin failed to free a context buffer for each connection. (Bug #16591288)
• The DBUG_PRINT() macro unnecessarily evaluated arguments when debugging was not enabled. (Bug
#16556597)
• Geometry methods that worked with WKB data performed insufficient input data validation, which could
cause Valgrind errors or a server exit. (Bug #16510712, Bug #12772601)
• The server could attempt a filesort operation for a zero-size sort length, causing it to exit. (Bug
#16503160)
• Opening a cursor on a SELECT within a stored procedure could cause a segmentation fault. (Bug
#16499751)
References: This issue is a regression of: Bug #14740889.
109
MySQL 5.6 Release Notes
• my_load_defaults() was modified to accommodate some problems under compilation with gcc
4.7.2 that could cause a client crash during option processing. (Bug #16497125)
• SET PASSWORD treated [email protected]'%' and [email protected]'' as referring to the same mysql.user table row. (Bug
#16488043)
• When index condition pushdown was used on a descending range scan and the first range interval
did not contain any qualifying records, the result of the range scan could be empty even if other range
intervals contained qualifying records. (Bug #16483273)
• The WKB reader for spatial operations could fail and cause a server exit. (Bug #16451878)
• Optimizer heuristics inappropriately preferred range access over ref access in cases when the ref
access referred to a column of a table earlier in the join seqence. (Bug #16437940)
• Performance Schema parameter autosizing at startup did not take into account later autosizing changes
to other startup parameters on which the Performance Schema parameters depended. (Bug #16430532)
• Some INFORMATION_SCHEMA queries that used ORDER BY did not use a filesort optimization as
they did in MySQL 5.5. (Bug #16423536)
• Manually-created accounts (using INSERT) with a malformed password effectively had no password.
(Bug #16414396)
• For debug builds, DBUG_EXPLAIN resulted in a buffer overflow when the debug system variable value
was more than 255 characters. (Bug #16402143)
• Several scripts in the sql-bench directory that were supposed to be executable did not have the
executable access bit set. (Bug #16395606)
• For debug builds, with an XA transaction in IDLE or PREPARED status, execution of a query with the
query cache enabled could cause a server exit. (Bug #16388996)
• Installing Debian packages on Ubuntu 12.10 succeeded using dpkg, but not with Software Center
5.4.1.4. (Bug #16387513)
• Within an XA transaction in ACTIVE state, statements causing an implicit commit could result in
metadata locks being released too early. (Bug #16362832)
• For debug builds, GROUP_CONCAT(... ORDER BY) within an ORDER BY clause could cause a server
exit. (Bug #16347426)
• A GROUP_CONCAT() invocation containing subquery having an outer reference caused the server to
exit. (Bug #16347343)
• The validate_password plugin did not always enforce appropriate constraints against assigning
empty passwords. (Bug #16346443)
• Re-execution of a stored procedure could cause a server exit in Item_field::fix_outer_field.
(Bug #16317443)
• For debug builds, the server could exit for queries involving a nested subquery, a subquery transformed
into a semi-join and using a view. (Bug #16317076)
• thread_pool_high_priority_connection could not be set at server startup. (Bug #16310373)
• With secure_auth enabled, a user with a password that used the pre-4.1 (old) hashing could not
update it to use the 4.1 (new) hashing. (Bug #16304018)
110
MySQL 5.6 Release Notes
• The range optimizer could set up incorrect ranges for queries that used XOR operations. (Bug
#16272562)
• mysql_secure_installation could not connect to the server if the account used had an
expired password. It invoked mysql noninteractively, resulting in that program failing to connect.
Now mysql supports a --connect-expired-password option that indicates to the server that
it can handle sandbox mode for expired-password accounts even if invoked noninteractively, and
mysql_secure_installation invokes mysql with this option. (Bug #16248315)
• If loose index scan was used on a query that used MIN(), a segmentation fault could occur. (Bug
#16222245)
• An outer join between a regular table and a derived table that is implicitly groups could cause a server
exit. (Bug #16177639)
• If multiple statements were sent in a single request, the audit log plugin logged only the last one. Now it
logs each statement separately. (Bug #16169063)
• For debug builds, an assertion was incorrectly raised for queries executed using eq_ref access and
filesort. (Bug #16164885)
• A prepared statement that used GROUP_CONCAT() and an ORDER BY clause that named multiple
columns could cause the server to exit. (Bug #16075310)
• ORDER BY MATCH ... AGAINST could cause a server exit. (Bug #16073689)
• Creating a FEDERATED table without specifying a connection string caused a server exit. (Bug
#16048546)
• Client programs from MySQL 5.6.4 and up could confuse older servers during the connection process by
using newer protocol features not understood by older servers. (Bug #15965409)
• The mysql.server script exited with an error if the status command was executed with multiple
servers running. (Bug #15852074)
• In some cases, REVOKE could fail to revoke the GRANT OPTION privilege. (Bug #14799187)
• Use of the VALUES() function in the VALUES() clause of an INSERT statement could result in Valgrind
warnings or an unstable server, possibly leading to a server exit. (Bug #14789787)
• The mysql client allocated but did not free a string after reading each line in interactive mode, resulting
in a memory leak. (Bug #14685362)
• Killing a connection while it was in the process of disconnecting could lead to an assertion being raised,
Valgrind warnings, and general unstability. (Bug #14560522)
• INSERT ... ON DUPLICATE KEY UPDATE on a view could cause a server exit. (Bug #14261010)
• Grouping by an outer BLOB column in a subquery caused a server exit. (Bug #13966809, Bug
#14700180)
• The server could exit due to improper handling of the error from an invalid comparison. (Bug #13009341)
• The CMake check for unsigned time_t failed on all platforms. (Bug #11766815)
• mysqladmin debug causes the server to write debug information to the error log. On systems that
supported mallinfo(), the memory-status part of this output was incorrect in 64-bit environments
when mysqld consumed more than 4GB memory.
111
MySQL 5.6 Release Notes
Now the server uses malloc_info() to obtain memory-status information. malloc_info() does
not report the memory that the glibc malloc() implementation internally allocates using mmap().
However, it does provide the memory usage information in all the memory arenas.
This bug fix also involves a change of output format. The server now writes memory information in XML
format rather than as plain text. Example:
Memory status:
<malloc version="1">
<heap nr="0">
<sizes>
<size from="33" to="33" total="1056" count="32"/>
<size from="65" to="65" total="65" count="1"/>
<size from="113" to="113" total="226" count="2"/>
<size from="129" to="129" total="2451" count="19"/>
<size from="145" to="145" total="290" count="2"/>
<size from="161" to="161" total="1288" count="8"/>
<size from="209" to="209" total="418" count="2"/>
</sizes>
<total type="fast" count="0" size="0"/>
<total type="rest" count="66" size="5794"/>
<system type="current" size="10833920"/>
<system type="max" size="10833920"/>
<aspace type="total" size="10833920"/>
<aspace type="mprotect" size="10833920"/>
</heap>
<total type="fast" count="0" size="0"/>
<total type="rest" count="66" size="5794"/>
<system type="current" size="10833920"/>
<system type="max" size="10833920"/>
<aspace type="total" size="10833920"/>
<aspace type="mprotect" size="10833920"/>
</malloc>
(Bug #11746658)
• FOUND_ROWS() could return an incorrect value if the preceding query used filesort. (Bug #69119,
Bug #16760474)
References: This issue is a regression of: Bug #68458.
• The optimizer could choose a poor execution plan for queries with ORDER BY ... LIMIT. (Bug
#69013, Bug #16697792)
• When specified in an option file, the plugin-dir client option was ignored. (Bug #68800, Bug
#16680313)
• When only counting events but not timing them, Performance Schema would report MIN_TIMER_WAIT
values as a large number instead of 0. (Bug #68768, Bug #16552425)
• Using range access with an index prefix could produce incorrect results. (Bug #68750, Bug #16540042)
• For debug builds, metadata locking for CREATE TABLE ... SELECT could raise an assertion. (Bug
#68695, Bug #16503173)
• mysqld --help and mysqld --verbose --help performed unnecessary logging. (Bug #68578, Bug
#16442113)
• A new CMake option, WITH_EDITLINE, is provided to indicate whether to use the bundled or system
libedit/editline library. The permitted values are bundled (the default) and system.
112
MySQL 5.6 Release Notes
WITH_EDITLINE replaces WITH_LIBEDIT, which has been removed. (Bug #68558, Bug #16430208)
• If Loose Index Scan was used to evaluate a query that compared an integer column to an integer
specified as a quoted string (for example, col_name = '1'), the query could return incorrect results.
(Bug #68473, Bug #16394084)
• In a MySQL server newer than MySQL 5.5 using a nonupgraded mysql.user table (for which
mysql_upgrade had not been run), statements to set passwords caused a server exit due to a faulty
check for the password_expired column. (Bug #68385, Bug #16339767)
• Indexes on derived tables that were used during the first invocation of a stored procedure were not used
in subsequent invocations. (Bug #68350, Bug #16346367)
• If a function such as AES_DECRYPT() that requires SSL support failed, the error could affect later calls
to functions that require SSL support. (Bug #68340, Bug #16315767)
• For DELETE and UPDATE statements, EXPLAIN displayed NULL in the ref column for some cases
where const is more appropriate. (Bug #68299, Bug #16296268)
• The mysql client incorrectly used latin1 for certain comparisons even if started with a multibyte
default character set, resulting in a client crash. (Bug #68107, Bug #16182919)
• InnoDB does not support full-text parser plugins, but failed to report an error if they were specified. Now
an ER_INNODB_NO_FT_USES_PARSER error is returned. (Bug #62004, Bug #12843070)
• The url columns in the mysql datatbase help tables were too short to hold some of the URLs in
the help content. These columns are now created as type TEXT to accommodate longer URLs. (Bug
#61520, Bug #12671635)
• Two problems adding or subtracting keyword from the current debug system variable setting were
corrected:
• A debug value of 'd' means “all debug macros enabled”. The following sequence left the value in an
incorrect state:
mysql> SET debug = 'd';SELECT @@debug;
+---------+
| @@debug |
+---------+
| d
|
+---------+
mysql> SET debug = '+d,M1';SELECT @@debug;
+---------+
| @@debug |
+---------+
| d,M1
|
+---------+
The first SET statement enables all debug macros. The second SET should add the M1 macro to the
current set, which should result in no change because the current set is already “all macros”. Instead,
the second SET reset the current set to only the M1 macro, effectively disabling all others. The server
now correctly leaves debug set to 'd'.
• A debug value of '' means “no debug macros enabled”. The following sequence left the value in an
incorrect state:
113
MySQL 5.6 Release Notes
mysql> SET debug = 'd,M1';SELECT @@debug;
+---------+
| @@debug |
+---------+
| d,M1
|
+---------+
mysql> SET debug = '-d,M1';SELECT @@debug;
+---------+
| @@debug |
+---------+
| d
|
+---------+
The first SET statement sets debug to the M1* macro. The second SET should subtract the M1 macro
from the current set, leaving no debug macros enabled. Instead, the second SET reset the current set
to 'd' (all macros enabled). The server now correctly sets debug to ''.
(Bug #58630, Bug #11765644)
• It is now possible to suppress installation of the mysql-test directory after compiling MySQL from
source by invoking CMake with the INSTALL_MYSQLTESTDIR option explicitly set to empty:
cmake . -DINSTALL_MYSQLTESTDIR=
Previously, attempts to do this resulted in an error. (Bug #58615, Bug #11765629)
• On 64-bit OS X systems, CMake used x86 rather than x86_64 when determining the machine type.
(Bug #58462, Bug #11765489)
• IF() function evaluations could produce different results when executed in a prepared versus
nonprepared statement. (Bug #45370, Bug #11753852)
Changes in MySQL 5.6.11 (2013-04-18, General Availability)
A known limitation of this release:
Note
If you have InnoDB tables with full-text search indexes and you are upgrading from
MySQL 5.6.10 to a MySQL version up to and including MySQL 5.6.18, the server
will fail to start after the upgrade (Bug#72079). This bug is fixed in MySQL 5.6.19.
As a workaround, remove full-text search indexes prior to upgrading and rebuild fulltext search indexes after the upgrade is completed.
• RPM Notes
• Functionality Added or Changed
• Bugs Fixed
RPM Notes
• It was not possible to upgrade a community RPM to a commercial RPM using rpm -uvh or yum
localupdate. To deal with this, the RPM spec file has been updated in MySQL 5.6.11, which has the
following consequences:
114
MySQL 5.6 Release Notes
• For a non-upgrade installation (no existing MySQL version installed), it possible to install MySQL using
yum.
• For upgrades, it is necessary to clean up any earlier MySQL installations. In effect, the update is
performed by removing the old installations and installing the new one.
Additional details follow.
For a non-upgrade installation of MySQL 5.6.11, it is possible to install using yum:
shell> yum install MySQL-server-NEWVERSION.glibc23.i386.rpm
For upgrades to MySQL 5.6.11, the upgrade is performed by removing the old installation and installing
the new one. To do this, use the following procedure:
1. Remove the existing 5.6.X installation. OLDVERSION is the version to remove.
shell> rpm -e MySQL-server-OLDVERSION.glibc23.i386.rpm
Repeat this step for all installed MySQL RPMs.
2. Install the new version. NEWVERSION is the version to install.
shell> rpm -ivh MySQL-server-NEWVERSION.glibc23.i386.rpm
Alternatively, the removal and installation can be done using yum:
shell> yum remove MySQL-server-OLDVERSION.glibc23.i386.rpm
shell> yum install MySQL-server-NEWVERSION.glibc23.i386.rpm
(Bug #16445097, Bug #16445125, Bug #16587285)
Functionality Added or Changed
• Replication: The functions GTID_SUBTRACT() and GTID_SUBSET() were formerly available in
libmysqld only when it was built with replication support. Now these functions are always available
when using this library, regardless of how it was built.
• MySQL no longer uses the default OpenSSL compression. (Bug #16235681)
• There is now a distinct error code (ER_MUST_CHANGE_PASSWORD_LOGIN) for the error sent by the
server to a client authenticating with an expired password. (Bug #16102943)
• mysql_config_editor now supports --port and --socket options for specifying TCP/IP port
number and Unix socket file name. (Bug #15851247)
• mysqlcheck has a new --skip-database option. The option value is the name of a database (case
sensitive) for which checks should be skipped.
mysql_upgrade adds this option to mysqlcheck commands that it generates to upgrade the system
tables in the mysql database before tables in other databases: It upgrades the mysql database, then all
databases except the mysql database. This avoids problems that can occur if user tables are upgraded
before the system tables. (Bug #14697538, Bug #68163, Bug #16216384)
115
MySQL 5.6 Release Notes
• The only supported value for the innodb_mirrored_log_groups system variable is 1, so this
variable is now deprecated. Setting it to 1 at startup results in a warning. Setting it to a value other than 1
at startup results in an error and the server exits. This variable will be removed in a future release.
Bugs Fixed
• Incompatible Change; Partitioning: Changes in the KEY partitioning hashing functions used with
numeric, date and time, ENUM, and SET columns in MySQL 5.5 makes tables using partitioning or
subpartitioning by KEY on any of the affected column types and created on a MySQL 5.5 or later server
incompatible with a MySQL 5.1 server. This is because the partition IDs as calculated by a MySQL 5.5
or later server almost certainly differ from those calculated by a MySQL 5.1 server for the same table
definition and data as a result of the changes in these functions.
The principal changes in the KEY partitioning implementation in MySQL 5.5 resulting in this issue were
as follows: 1. The hash function used for numeric and date and time columns changed from binary to
character-based. 2. The base used for hashing of ENUM and SET columns changed from latin1 ci
characters to binary.
The fix involves adding the capability in MySQL 5.5 and later to choose which type of hashing to use
for KEY partitioning, which is implemented with a new ALGORITHM extension to the PARTITION BY
KEY option for CREATE TABLE and ALTER TABLE. Specifying PARTITION BY KEY ALGORITHM=1
([columns]) causes the server to use the hashing functions as implemented in MySQL 5.1; using
ALGORITHM=2 causes the server to use the hashing functions from MySQL 5.5 and later. ALGORITHM=2
is the default. Using the appropriate value for ALGORITHM, you can perform any of the following tasks:
• Create KEY partitioned tables in MySQL 5.5 and later that are compatible with MySQL 5.1, using
CREATE TABLE ... PARTITION BY KEY ALGORITHM=1 (...).
• Downgrade KEY partitioned tables that were created in MySQL 5.5 or later to become compatible with
MySQL 5.1, using ALTER TABLE ... PARTITION BY KEY ALGORITHM=1 (...).
• Upgrade KEY partitioned tables originally created in MySQL 5.1 to use hashing as in MySQL 5.5 and
later, using ALTER TABLE ... PARTITION BY KEY ALGORITHM=2 (...).
Important: After such tables are upgraded, they cannot be used any longer with MySQL 5.1 unless
they are first downgraded again using ALTER TABLE ... PARTITION BY KEY ALGORITHM=1
(...) on a MySQL server supporting this option.
This syntax is not backward compatible, and causes errors in older versions of the MySQL server.
When generating CREATE TABLE ... PARTITION BY KEY statements, mysqldump brackets any
occurrence of ALGORITHM=1 or ALGORITHM=2 in conditional comments such that it is ignored by a
MySQL server whose version is not at least 5.5.31. An additional consideration for upgrades is that
MySQL 5.6 servers prior to MySQL 5.6.11 do not ignore the ALGORITHM option in such statements when
generated by a MySQL 5.5 server, due to the that the conditional comments refer to version 5.5.31; in
this case, you must edit the dump manually and remove or comment out the option wherever it occurs
before attempting to load it into a MySQL 5.6.10 or earlier MySQL 5.6 server. This is not an issue for
dumps generated by MySQL 5.6.11 or later version of mysqldump, where the version used in such
comments is 5.6.11. For more information, see ALTER TABLE Partition Operations.
As part of this fix, a spurious assertion by InnoDB that a deleted row had previously been read, causing
the server to assert on delete of a row that the row was in the wrong partition, was also removed. (Bug
#14521864, Bug #66462, Bug #16093958, Bug #16274455)
References: See also: Bug #11759782.
116
MySQL 5.6 Release Notes
• Incompatible Change: For debug builds, creating an InnoDB table in strict SQL mode that violated the
maximum key length limit caused the server to exit.
A behavior change in consequence of this bug fix: In strict SQL mode, a key length limit violation now
results in a error (and the table is not created), rather than a warning and truncation of the key to the
maximum key length. This applies to all storage engines. (Bug #16035659)
• Important Change; Replication
Important
This fix was reverted in MySQL 5.6.12. See Changes in MySQL 5.6.12
(2013-06-03, General Availability).
Executing a statement that performs an implicit commit but whose changes are not logged when
gtid_next is set to any value other than AUTOMATIC is not permitted. Now in such cases, the
statement fails with an error. This includes the statements in the following list:
• CHANGE MASTER TO
• START SLAVE
• STOP SLAVE
• REPAIR TABLE
• OPTIMIZE TABLE
• ANALYZE TABLE
• CHECK TABLE
• CREATE SERVER
• ALTER SERVER
• DROP SERVER
• CACHE INDEX
• LOAD INDEX INTO CACHE
• FLUSH
• RESET
(Bug #16062608)
References: See also: Bug #16484323.
• Important Change; Replication: The version number reported by mysqlbinlog --version has been
increased to 3.4. (Bug #15894381, Bug #67643)
• Important Note; Replication: Using row-based logging to replicate from a table to a same-named view
led to a failure on the slave. Now, when using row-based logging, the target object type is checked prior
to performing any DML, and an error is given if the target on the slave is not actually a table.
117
MySQL 5.6 Release Notes
Note
It remains possible to replicate from a table to a same-named view using
statement-based logging.
(Bug #11752707, Bug #43975)
• Performance; InnoDB: Switching the MySQL table used by the InnoDB memcached interface (using
the @@ notation), was made more efficient, by reading cached information about the cache policy to use
for each table. This optimization lets you frequently switch between tables during a session that uses the
memcached interface, without incurring I/O overhead from examining table metadata each time. (Bug
#16206654)
• Performance; InnoDB: Performance was improved for operations on tables with many rows that were
deleted but not yet purged. The speedup applies mainly to workloads that perform bulk deletes, or
updates to the primary key columns, and where the system is busy enough to experience purge lag.
(Bug #16138582, Bug #68069)
• Performance; InnoDB: The DROP TABLE statement for a table using compression could be slower than
necessary, causing a stall for several seconds. MySQL was unnecessarily decompressing pages in the
buffer pool related to the table as part of the DROP operation. (Bug #16067973)
• Performance; InnoDB: The I/O routines used when the AIO subsystem were made more efficient, to
merge consecutive I/O requests into a single operation. This fix solves a performance issue introduced
during the 5.6 development cycle. (Bug #16043841, Bug #67973)
• InnoDB: When ADD PRIMARY KEY columns are reordered in an ALTER TABLE statement (for
example: ALTER TABLE t1 ADD PRIMARY KEY(a,b), CHANGE a a INT AFTER b), the log apply
for UPDATE operations failed to find rows. (Bug #16586355)
• InnoDB: ALTER TABLE operations on InnoDB tables that added a PRIMARY KEY using a column prefix
could produce an incorrect result. (Bug #16544336)
• InnoDB: For ALTER TABLE operations on InnoDB tables that required a table-copying operation,
other transactions on the table might fail during the copy. However, if such a transaction issued a partial
rollback, the rollback was treated as a full rollback. (Bug #16544143)
• InnoDB: When parsing a delimited search string such as “abc-def” in a full-text search, InnoDB now
uses the same word delimiters as MyISAM. (Bug #16419661)
• InnoDB: Naming inconsistencies were addressed for InnoDB PERFORMANCE_SCHEMA key declarations.
(Bug #16414044)
• InnoDB: Status values in the innodb_ft_config table would not update. The innodb_ft_config
is intended for internal configuration and should not be used for statistical information purposes.
To avoid confusion, column values that are intended for internal use have been removed from the
innodb_ft_config table. This fix also removes the innodb_ft_config table and other internal full
text search-related tables that were unintentionally exposed. (Bug #16409494, Bug #68502)
• InnoDB: Crash recovery failed with a !recv_no_log_write assertion when reading a page. (Bug
#16405422)
• InnoDB: This fix disables a condition for extra splitting of clustered index leaf pages, on compressed
tables. Extra page splitting was only done to reserve space for future updates, so that future page splits
could be avoided. (Bug #16401801)
118
MySQL 5.6 Release Notes
• InnoDB: For InnoDB tables, if a PRIMARY KEY on a VARCHAR column (or prefix) was empty, index
page compression could fail. (Bug #16400920)
• InnoDB: The InnoDB page-splitting algorithm could recurse excessively. (Bug #16345265)
• InnoDB: Improper testing of compatibility between the referencing and referenced during ALTER
TABLE ... ADD FOREIGN key could cause a server exit. (Bug #16330036)
• InnoDB: Importing a tablespace with the configuration file present would not import the data file. This
problem would occur when all pages are not flushed from the buffer pool after a table is altered using the
copy and rename approach. This fix ensures that all pages are flushed from the buffer pool when a table
is altered using the copy and rename approach. (Bug #16318052)
• InnoDB: Rollback did not include changes made to temporary tables by read-only transactions. (Bug
#16310467)
• InnoDB: When using ALTER TABLE to set an AUTO_INCREMENT column value to a userspecified value, InnoDB would set the AUTO_INCREMENT value to the user-specified value
even when the AUTO_INCREMENT value is greater than the user-specified value. This fix
ensures that the AUTO_INCREMENT value is set to the maximum of the user-specified value and
MAX(auto_increment_column)+1, which is the expected behaviour. (Bug #16310273)
• InnoDB: RENAME TABLE would result in a hang due to a MySQL mutex acquisition deadlock. (Bug
#16305265)
• InnoDB: For debug builds, InnoDB status exporting was subject to a race condition that could cause a
server exit. (Bug #16292043)
• InnoDB: With innodb_api_enable_mdl=OFF, an ALTER TABLE operation on an InnoDB table that
required a table copy could cause a server exit. (Bug #16287411)
• InnoDB: An assertion failure would occur in heap->magic_n == MEM_BLOCK_MAGIC_N due to a
race condition that appeared when row_merge_read_clustered_index() returned an error. (Bug
#16275237)
• InnoDB: InnoDB now aborts execution on Windows by calling the abort() function directly, as it does
on other platforms. (Bug #16263506)
• InnoDB: This fix removes an unnecessary debug assertion related to page_hash locks which only
affects debug builds. The debug assertion is no longer valid and should have been removed when
hash_lock array was introduced in MySQL 5.6. (Bug #16263167)
• InnoDB: Internal read operations could be misclassified as synchronous when they were actually
asynchronous. When the I/O requests returned sooner than expected, threads could be scheduled
inefficiently. This issue mainly affected read-ahead requests, and thus had relatively little impact on I/O
performed by user queries. (Bug #16249505, Bug #68197)
• InnoDB: The lock_validate function, which is only present in debug builds, acquired and released
mutexes to avoid hogging them. This behavior introduced a window wherein changes to the hash table
could occur while code traversed the same set of data. This fix updates lock_validate logic to collect
all records for which locks must be validated, releases mutexes, and runs a loop to validate record locks.
(Bug #16235056)
• InnoDB: ALTER TABLE functions would perform a check to see if InnoDB is in read-only mode
(srv_read_only_mode=true). If InnoDB was in read-only mode, the check would return a successful
status and do nothing else. This fix replaces srv_read_only_mode check conditions with debug
assertions. (Bug #16227539)
119
MySQL 5.6 Release Notes
• InnoDB: When the InnoDB buffer pool is almost filled with 4KB compressed pages, inserting into 16KB
compact tables would cause 8KB pages_free to increase, which could potentially slow or stall inserts.
(Bug #16223169)
• InnoDB: This fix updates InnoDB code in ha_innodb.cc and handler0alter.cc to use
TABLE::key_info instead of both TABLE::key_info and TABLE_SHARE::key_info. (Bug
#16215361)
• InnoDB: When InnoDB locking code was revised, a call to register lock waits was inadvertently
removed. This fix adds the call back to the InnoDB locking code. (Bug #16208201)
• InnoDB: If the MySQL server halted at a precise moment when a purge operation was being applied
from the change buffer, the operation could be incorrectly performed again during the next restart. A
workaround was to set the configuration option innodb_change_buffering=changes, to turn off
change buffering for purge operations. (Bug #16183892, Bug #14636528)
• InnoDB: The InnoDB memcached plugin could encounter a serious error under a heavy load, such as
produced by benchmark runs. (Bug #16182660, Bug #68096)
• InnoDB: A direct call to the trx_start_if_not_started_xa_low() function would cause a debug
assertion. (Bug #16178995)
• InnoDB: In the case of LOCK WAIT for an insert in a foreign key table, InnoDB could report a false
dictionary-changed error and cause the insert to fail rather than being retried. (Bug #16174255)
• InnoDB: An in-place ALTER TABLE on an InnoDB table could fail to delete the statistics for the old
primary key from the mysql.innodb_index_stats table. (Bug #16170451)
• InnoDB: In some cases, deadlock detection did not work, resulting in sessions hanging waiting for a
lock-wait timeout. (Bug #16169638)
• InnoDB: Arithmetic underflow during page compression for CREATE TABLE on an InnoDB table could
cause a server exit. (Bug #16089381)
• InnoDB: For debug builds, online ALTER TABLE operations for InnoDB tables could cause a server exit
during table rebuilding. (Bug #16063835)
• InnoDB: In some cases, the InnoDB purge coordinator did not use all available purge threads, resulting
in suboptimal purge activity. (Bug #16037372)
• InnoDB: On systems that cannot handle unaligned memory access, depending on the stack frame
alignment, a SIGBUS error could occur during startup. This issue was observed on Solaris 64-bit
systems. (Bug #16021177)
• InnoDB: ALTER TABLE for InnoDB tables was not fully atomic. (Bug #15989081)
• InnoDB: When innodb_mirrored_log_groups was set to a value other than the default 1, the
MySQL server encountered a serious error during startup while loading the InnoDB memcached plugin.
In earlier releases, the server would refuse to start (but not display an error) when this setting was
changed. This fix cleans up the error handling for unsupported values of this configuration option. (Bug
#15907954, Bug #67670)
• InnoDB: The innodb_sync_array_size variable was incorrectly allowed to be configured at runtime.
As documented, innodb_sync_array_size must be configured when the MySQL instance is starting
up, and cannot be changed afterward. This fix changes innodb_sync_array_size to a non-dynamic
variable, as intended. (Bug #14629979)
120
MySQL 5.6 Release Notes
• InnoDB: An error at the filesystem level, such as too many open files, could cause an unhandled error
during an ALTER TABLE operation. The error could be accompanied by Valgrind warnings, and by this
assertion message:
Assertion `! is_set()' failed.
mysqld got signal 6 ;
(Bug #14628410, Bug #16000909)
• InnoDB: The server could exit during an attempt by InnoDB to reorganize or compress a compressed
secondary index page. (Bug #14606334)
• InnoDB: A RENAME TABLE statement could stall for several minutes before timing out. This issue could
occurred for a table using compression, with change buffering enabled. (Bug #14556349)
• InnoDB: A DML operation performed while a RENAME TABLE operation waits for pending I/O operations
on the tablespace to complete would result in a deadlock. (Bug #14556349)
• InnoDB: If the server was started with the skip-innodb option, or InnoDB otherwise failed to start,
query any of these Information Schema tables would cause a severe error:
• INNODB_BUFFER_PAGE
• INNODB_BUFFER_PAGE_LRU
• INNODB_BUFFER_POOL_STATS
(Bug #14144290)
• InnoDB: Online DDL had a restriction that prevented renaming a column and adding a foreign key
involving that column in a single ALTER TABLE statement. Now, this combination of operations is
allowed in a single statement. (Bug #14105491)
• InnoDB: When printing out long semaphore wait diagnostics, sync_array_cell_print() ran into
a segmentation violation (SEGV) caused by a race condition. This fix addresses the race condition by
allowing the cell to be freed while it is being printed. (Bug #13997024)
• InnoDB: The value of the innodb_version variable was not updated consistently for all server
releases for the InnoDB Plugin in MySQL 5.1, and the integrated InnoDB component in MySQL 5.5, 5.6,
and higher. Since InnoDB and MySQL Server development cycles are fully integrated and synchronized,
now the value returned by the innodb_version variable is the same as for the version variable. (Bug
#13463493, Bug #63435)
• InnoDB: Attempting to replace the default InnoDB full-text search (FTS) stopword list by creating an
InnoDB table with the same structure as INFORMATION_SCHEMA.INNODB_FT_DEFAULT_STOPWORD
would result in an error. SHOW CREATE TABLE revealed that the new InnoDB table was created with
CHARSET=utf8. The InnoDB FTS stopword table validity check only supported latin1. This fix extends
the validity check for all supported character sets. (Bug #68450, Bug #16373868)
• InnoDB: This fix removes left-over prototype code for srv_parse_log_group_home_dirs, and
related header comments. (Bug #68133, Bug #16198764)
• InnoDB: Killing a query caused an InnoDB assertion failure when the same table (cursor) instance
was used again. This is the result of a regression error introduced by the fix for Bug#14704286. The fix
introduced a check to handle kill signals for long running queries but the cursor was not restored to the
proper state. (Bug #68051, Bug #16088883)
121
MySQL 5.6 Release Notes
• InnoDB: On startup, InnoDB reported a message on 64-bit Linux and 64-bit Windows systems stating
that the CPU does not support crc32 instructions. On Windows, InnoDB does not use crc32 instructions
even if supported by the CPU. This fix revises the wording of the message and implements a check for
availability of crc32 instructions. (Bug #68035, Bug #16075806)
• InnoDB: The length of internally generated foreign key names was not checked. If internally generated
foreign key names were over the 64 character limit, this resulted in invalid DDL from SHOW CREATE
TABLE. This fix checks the length of internally generated foreign key names and reports an error
message if the limit is exceeded. (Bug #44541, Bug #11753153)
• Partitioning: ALGORITHM = INPLACE, which was disallowed in MySQL 5.6.10 for DDL statements
operating on partitioned tables, can once again be used with such statements. (Bug #16216513)
References: See also: Bug #14760210.
• Partitioning: A query on a table partitioned by range and using TO_DAYS() as a partitioing function
always included the first partition of the table when pruning. This happened regardless of the range
employed in the BETWEEN clause of such a query. (Bug #15843818, Bug #49754)
• Partitioning: Execution of ALTER TABLE ... DROP PARTITION against a view caused the server to
crash, rather than fail with an error as expected. (Bug #14653504)
• Partitioning: A query result was not sorted if both DISTINCT and ORDER BY were used and the
underlying table was partitioned. (Bug #14058167)
• Partitioning: Inserting any number of rows into an ARCHIVE table that used more than 1000 partitions
and then attempting to drop the table caused the MySQL Server to fail. (Bug #13819630, Bug #64580)
• Replication: When using GTIDs and binary log auto-positioning, the master had to scan all binary logs
whenever the slave reconnected (due to reasons such as I/O thread failure or a change of master)
before it could send any events to slave. Now, the master starts from the oldest binary log that contains
any GTID not found on the slave. (Bug #16340322, Bug #68386)
• Replication: When the server version of the master was greater than or equal to 10, replication to a
slave having a lower server version failed. (Bug #16237051, Bug #68187)
• Replication: When replicating to a MySQL 5.6 master to an older slave, Error 1193
(ER_UNKNOWN_SYSTEM_VARIABLE) was logged with a message such as Unknown system
variable 'SERVER_UUID' on master, maybe it is a *VERY OLD MASTER*. This message
has been improved to include more information, similar to this one: Unknown system variable
'SERVER_UUID' on master. A probable cause is that the variable is not
supported on the master (version: 5.5.31), even though it is on the slave
(version: 5.6.11). (Bug #16216404, Bug #68164)
• Replication: When MTS is on and transactions are being applied, the slave coordinator would hang
when encountering a checksum error on a transaction event. This was due to a deadlock situation in
which the coordinator assumed a normal stop while a worker waited for the coordinator to dispatch
more events. For debug builds, the problem appeared as an assertion failure, which was due to the
coordinator not setting thd->is_error() when encountering an error. (Bug #16210351)
• Replication: A zero-length name for a user variable (such as @``) was incorrectly considered to be a
sign of data or network corruption when reading from the binary log. (Bug #16200555, Bug #68135)
• Replication: mysqlbinlog can connect to a remote server and read its binary logs. In MySQL 5.6 and
later, this tool can also wait for the server to generate and send additional events, in practice behaving
like a slave connecting to a master. In cases where the server sent a heartbeat, mysqlbinlog was
unable to handle it properly. As a consequence, mysqlbinlog failed at this point, without reading any
122
MySQL 5.6 Release Notes
more events from the server. To fix this problem, mysqlbinlog now ignores any binary log events of
type HEARTBEAT_LOG_EVENT that it receives. (Bug #16104206)
• Replication: STOP SLAVE could cause a deadlock when issued concurrently with a statement
such as SHOW STATUS that retrieved the values for one or more of the status variables
Slave_retried_transactions, Slave_heartbeat_period, Slave_received_heartbeats,
Slave_last_heartbeat, or Slave_running. (Bug #16088188, Bug #67545)
References: See also: Bug #16088114.
• Replication: Backtick (`) characters were not always handled correctly in internally generated SQL
statements, which could sometimes lead to errors on the slave. (Bug #16084594, Bug #68045)
References: This issue is a regression of: Bug #14548159, Bug #66550.
• Replication: In order to provision or to restore a server using GTIDs, it is possible to set gtid_purged
to a given GTID set listing the transactions that were imported. This operation requires that the global
gtid_executed and gtid_purged server system variables are empty. (This is done in order to avoid
the possibility of overriding server-generated GTIDs.)
The error message GTID_PURGED can only be set when GTID_EXECUTED is empty that
was raised when this requirement was not met could be confusing or misleading because it did not
specify the scope of the affected variables. To prevent this from happening, error messages that refer
to variables relating to GTIDs now specify the scope of any such variables when they do so. (Bug
#16084426, Bug #68038)
• Replication: The session-level value for gtid_next was incorrectly reset on the slave for all rollbacks,
which meant that GTIDs could be lost for multi-statement transactions, causing the slave to stop with an
ER_GTID_NEXT_TYPE_UNDEFINED_GROUP error. Now this is done only when a complete transaction is
being rolled back, or when autocommit is enabled. (Bug #16084206)
• Replication: Using the --replicate-* options (see Replication Slave Options and Variables) could in
some cases lead to a memory leak on the slave. (Bug #16056813, Bug #67983)
• Replication: In some cases, when the slave could not recognize the server version of the master, this
could cause the slave to fail. (Bug #16056365)
• Replication: In certain cases, the dump thread could send a heartbeat out of synchronisation with
format description events. One of the effects of this issue what that, after provisioning a new server
from a backup data directory and setting --gtid-mode=ON and enabling autopositioning (see
CHANGE MASTER TO Syntax), replication failed to start, with the error Read invalid event from
master.... The same problem could also cause GTID-based replication to fail due to skipped events
following a unplanned shutdown of the master. (Bug #16051857)
• Replication: Table IDs used in replication were defined as type ulong on the master and uint on the
slave. In addition, the maximum value for table IDs in binary log events is 6 bytes (281474976710655).
This combination of factors led to the following issues:
• Data could be lost on the slave when a table was assigned an ID greater than uint.
• Table IDs greater than 281474976710655 were written to the binary log as 281474976710655.
• This led to a stopped slave when the slave encountered two tables having the same table ID.
To fix these problems, IDs are now defined by both master and slave as type ulonglong but
constrained to a range of 0 to 281474976710655, restarting from 0 when it exceeds this value. (Bug
#14801955, Bug #67352)
123
MySQL 5.6 Release Notes
• Replication: Internal objects used for relay log information were only partially deleted before freeing
their memory. (Bug #14677824)
• Replication: It was possible in certain cases—immediately after detecting an EOF in the dump thread
read event loop, and before deciding whether to change to a new binary log file—for new events to be
written to the binary log before this decision was made. If log rotation occurred at this time, any events
that occurred following EOF detection were dropped, resulting in loss of data. Now in such cases, steps
are taken to make sure that all events are processed before allowing the log rotation to take place. (Bug
#13545447, Bug #67929)
References: See also: Bug #16016886.
• Replication: If the disk becomes full while writing to the binary log, the server hangs until space is freed
up manually. It was possible after this was done for the MySQL server to fail, due to an internal status
value being set when not needed. Now in such cases, rather than trying to set this status, a warning is
written in the error log instead. (Bug #11753923, Bug #45449)
• Microsoft Windows: In Shared Memory mode, the MySQL Server could crash when receiving requests
from multiple threads. (Bug #13934876)
• Solaris: mysql_install_db did not work in Solaris 10 sparse root zones. (Bug #68117, Bug
#16197860)
• InnoDB now reports row and table locks to the thread pool plugin. Deadlocks within a thread group
could occur otherwise. (Bug #16448639)
• Failure to handle a full-text search wildcard properly could cause the server to exit. (Bug #16446108)
• SHOW ENGINE PERFORMANCE_SCHEMA STATUS could report incorrect memory-allocation values when
the correct values exceeded 4GB. (Bug #16414644)
• The server could exit if a prepared statement attempted to create a table using the name of an existing
view while an SQL handler was opened. (Bug #16385711)
• Performance Schema statement tokenization overhead was reduced. (Bug #16382260)
• A long database name in a GRANT statement could cause the server to exit. (Bug #16372927)
• On Linux, a race condition involving epoll() could cause the thread pool plugin to miss events. This
was most likely on systems with greater than 16 cores. (Bug #16367483)
• Some aggregate queries attempted to allocate excessive memory. (Bug #16343992)
• For debug builds, an assertion could be raised if a statement failed with autocommit enabled just before
an XA START statement was issued. (Bug #16341673)
• Very small join_buffer_size values could cause an assertion to be raised. (Bug #16328373)
• The BUILD-CMAKE file in MySQL distributions was updated with the correct URL for CMake information.
(Bug #16328024)
• The optimizer's attempt to remove redundant subquery clauses raised an assertion when executing a
prepared statement with a subquery in the ON clause of a join in a subquery. (Bug #16318585)
References: This issue is a regression of: Bug #15875919.
• Incorrect results were returned if a query contained a subquery in an IN clause which contained an XOR
operation in the WHERE clause. (Bug #16311231)
124
MySQL 5.6 Release Notes
• A Valgrind failure could occur if a CREATE USER statement was logged to the general query log and the
old_passwords system variable was set to 2. (Bug #16300620)
• For debug builds, checking of password constraints could raise an assertion for statements that updated
passwords. (Bug #16289303)
• Conversion of numeric values to BIT could yield unexpected results. (Bug #16271540)
• Fixed warnings when compiling with XCode 4.6. Fixed warnings when compiling when the
_XOPEN_SOURCE or isoctal macro was already defined in the environment. (Bug #16265300, Bug
#60911, Bug #12407384)
• In the range optimizer, an index merge failure could cause a server exit. (Bug #16241773)
• For upgrade operations, RPM packages produced unnecessary errors about being unable to access
.err files. (Bug #16235828)
• Queries using range predicates that were evaluated using the LooseScan semi-join strategy could return
duplicate rows. (Bug #16221623)
References: This issue is a regression of: Bug #14728469.
• Certain legal HAVING clauses were rejected as invalid. (Bug #16221433)
• yaSSL did not perform proper padding checks, but instead examined only the last byte of cleartext and
used it to determine how many bytes to remove. (Bug #16218104)
• The Performance Schema could return incorrect values for the PROCESSLIST_INFO column of the
threads table. (Bug #16215165)
• A full-text query using Boolean mode could return zero results in some cases where the search term was
a quoted phrase:
• If the quoted phrase was preceded by a + sign. For example, this combination of a Boolean + operator
and a phrase would return zero results:
WHERE MATCH(content) AGAINST('+"required term due to plus sign"' IN BOOLEAN MODE)
• If the quoted phrase contained any stopwords. For example, the stopword "the" inside the phrase
caused the query to return zero results:
WHERE MATCH(content) AGAINST('"stopword inside the phrase"' IN BOOLEAN MODE)
(Bug #16206253, Bug #68150)
• mysql_config --libs displayed incorrect output. (Bug #16200717)
• Invocation of the range optimizer for a NULL select caused the server to exit. (Bug #16192219)
• If, in a SELECT, the HAVING clause contained a function call which itself contained an alias to a selected
expression, the server could sometimes exit. (Bug #16165981)
• For debug builds, the server could exit due to incorrect calculation of applicable indexes for a join that
involved const tables. (Bug #16165832)
• A bug in range optimization sometimes led to incorrect condition calculation for index merge union. This
could lead to missing rows. (Bug #16164031, Bug #68194, Bug #16229746)
125
MySQL 5.6 Release Notes
• For a CREATE TABLE (... col_name TIMESTAMP DEFAULT CURRENT_TIMESTAMP ...) ...
SELECT statement for which the SELECT did not provide a value for the TIMESTAMP column, that
column was set to '0000-00-00 00:00:00', not the current timestamp. (Bug #16163936)
• Using GROUP BY WITH ROLLUP in a prepared statement could cause the server to exit. (Bug
#16163596)
• With the thread pool plugin enabled, large numbers of connections could lead to a Valgrind panic or
failure of clients to be able to connect. (Bug #16088658, Bug #16196591)
• Performance Schema instrumentation was missing for slave worker threads. (Bug #16083949)
• The server executed EXPLAIN FORMAT=JSON for some malformed queries improperly. (Bug
#16078557)
• With statement-based binary logging, dropping a TEMPORARY InnoDB table could cause a segmentation
fault. (Bug #16076275)
• Setting the slave_rows_search_algorithms system variable to an inappropriate value could cause
the server to exit. (Bug #16074161)
• SET PASSWORD and GRANT ... IDENTIFIED BY have no effect on the password of a user who
is authenticated using an authentication plugin that accesses passwords stored externally to the
mysql.user table. But attempts to change the password of such a user produced no warning, leading
to the impression that the password had been changed when it was not. Now MySQL issues an
ER_SET_PASSWORD_AUTH_PLUGIN warning to indicate that the attempt was ignored. (Bug #16072004)
• Directory name manipulation could result in stack overflow on OS X and Windows. (Bug #16066243)
• The initial test database contained a dummy.bak file that prevented DROP DATABASE from working.
This file is no longer included. Also, a db.opt file is now included that contains these lines:
default-character-set=latin1
default-collation=latin1_swedish_ci
(Bug #16062056)
• Issuing a PREPARE statement using certain combinations of stored functions and user variables caused
the server to exit. (Bug #16056537)
• Setting a system variable to DEFAULT could cause the server to exit. (Bug #16044655)
• For debug builds, if the server was started with binary logging disabled, executing SHOW RELAYLOG
EVENTS from within a stored procedure raised an assertion. (Bug #16043173)
• The query parser leaked memory for some syntax errors. (Bug #16040022)
• During shutdown, the server could attempt to lock an uninitialized mutex. (Bug #16016493)
• The --default-authentication-plugin option permitted invalid plugin values, and did not always
set the old_passwords system variable to a value appropriate for the named plugin. (Bug #16014394)
• The --character-set-server option could set connection character set system variables to values
such as ucs2 that are not permitted. (Bug #15985752, Bug #23303391)
• Under some circumstances, mysql --secure-auth permitted passwords to be sent to the server
using the old (pre-4.1) hashing format. (Bug #15977433)
126
MySQL 5.6 Release Notes
• When a partition is missing, code in ha_innodb.cc would retry 10 times and sleep for a microsecond
each time while holding LOCK_open. The retry logic for partitioned tables was introduced as a fix for
Bug#33349 but did not include a test case to validate it. This fix removes the retry logic for partitioned
tables. If the problem reported in Bug#33349 reappears, a different solution will be explored. (Bug
#15973904)
• Joins of exactly 32 tables and containing a HAVING clause returned an empty result. (Bug #15972635)
• A mysys library string-formatting routine could mishandle width specifiers. (Bug #15960005)
• Table creation operations added entries to the file_instances Performance Schema table, but these
were not always removed for table drop operations. (Bug #15927620)
• With index condition pushdown enabled, queries for which the pushed-down condition contained no
columns in the used index could be slow. (Bug #15896009)
• A query with an EXISTS/IN/ALL/ANY subquery with an ORDER BY clause ordering by an outer column
of type BLOB that is not in the select list caused an assertion to fire. (Bug #15875919)
References: See also: Bug #14728142.
• In special cases, the optimizer did not consider indexes that were applicable to query processing,
resulting in potentially suboptimal execution and incorrect EXPLAIN output. (Bug #15849135, Bug
#16094171)
• Creating an InnoDB table with a FULLTEXT index could encounter a serious error if the table name
contained nonalphanumeric characters. (Bug #14835178, Bug #16036699)
• Enabling the query cache during high client contention could cause the server to exit. (Bug #14727815)
• The MSI Installer installed MySQL in “per-user” mode, which could result in conflicts or failure to detect
an existing installation if two users installed MySQL on the same machine. Now the MSI Installer uses
“per-machine” installation mode. (Bug #14711808)
• The server sometimes failed to respect MAX_CONNECTIONS_PER_HOUR limits on user connections. (Bug
#14627287)
• The optimizer could return incorrect results after transforming an IN subquery with aggregate functions
to an EXISTS subquery. (Bug #14586710)
• SET PASSWORD for anonymous users did not work correctly. (Bug #14561102)
• When a client program loses the connection to the MySQL server or if the server begins a shutdown
after the client has executed mysql_stmt_prepare(), the next mysql_stmt_prepare() returns an
error (as expected) but subsequent mysql_stmt_execute() calls crash the client. (Bug #14553380)
• Previously, if multiple --login-path options were given, mysql_config_editor ignored all but the
last one. Now multiple --login-path options result in an error. (Bug #14551712)
• SHOW COLUMNS on a view defined as a UNION of Geometry columns could cause the server to exit.
(Bug #14362617)
• The sha256_password_private_key_path and sha256_password_public_key_path system
variables indicate key files for the sha256_password authentication plugin, but the server failed to
properly check whether the key files were valid. Now in the event that either key file is invalid, the server
logs an error and exits. (Bug #14360513)
127
MySQL 5.6 Release Notes
• SET var_name = VALUES(col_name) could cause the server to exit. This syntax is now prohibited
because in SET context there is no column name and the statement returns ER_BAD_FIELD_ERROR.
(Bug #14211565)
• The COM_CHANGE_USER command in the client/server protocol did not properly use the character set
number in the command packet, leading to incorrect character set conversion of other values in the
packet. (Bug #14163155)
• Invoking the FORMAT() function with a locale and a very large number could cause the server to exit.
(Bug #14040155)
• yaSSL rejected some valid server SSL certificates. (Bug #13777928)
• Certain plugin-related conditions can make a user account unusable:
• The account requires an authentication plugin that is not loaded.
• The account requires the sha256_password authentication plugin but the server was started with
neither SSL nor RSA enabled as required by this plugin.
The server now checks those conditions by default and produces warnings for unusable accounts. This
checking slows down server initialization and FLUSH PRIVILEGES, so it is made optional by means of
the new validate_user_plugins system variable. This variable is enabled by default, but if you do
not require the additional checking, you can disable it at startup to avoid the performance decrement.
(Bug #13010061, Bug #14506305)
• Passing an unknown time zone specification to CONVERT_TZ() resulted in a memory leak. (Bug
#12347040)
• The obsolete linuxthreads.txt and glibc-2.2.5.patch files in the Docs directory of MySQL
distributions have been removed. (Bug #11766326)
• mysql_install_db did not escape '_' in the host name for statements written to the grant tables.
(Bug #11746817)
• With explicit_defaults_for_timestamp enabled, inserting NULL into a TIMESTAMP NOT NULL
column now produces an error (as it already did for other NOT NULL data types), instead of inserting the
current timestamp. (Bug #68472, Bug #16394472)
• Handling of SQL_CALC_FOUND_ROWS in combination with ORDER BY and LIMIT could lead to incorrect
results for FOUND_ROWS(). (Bug #68458, Bug #16383173)
• If INET6_NTOA() or INET6_ATON() returned NULL for a row in a result set, following rows also
returned NULL. (Bug #68454, Bug #16373973)
• A statement with an aggregated, nongrouped outer query and an aggregated, nongrouped subquery in
the SELECT list could return incorrect results. (Bug #68372, Bug #16325175)
• Adding an ORDER BY clause following an IN subquery could cause duplicate rows to be returned. (Bug
#68330, Bug #16308085)
• If the server was started with --skip-grant-tables, ALTER USER ... PASSWORD EXPIRE
caused the server to exit. (Bug #68300, Bug #16295905)
• Configuring with -DWITH_SSL=/path/to/openssl resulted in link errors due to selection of the
incorrect libcrypto. (Bug #68277, Bug #16284051)
128
MySQL 5.6 Release Notes
• If mysql is built with the bundled libedit library, the library is built as static code, to avoid linking to
a different dynamic version at runtime. Dynamic linking could result in use of a different, incompatible
version and a segmentation fault. (Bug #68231, Bug #16296509)
• Some table I/O performed by the server when calling a storage engine were missing from the statistics
collected by the Performance Schema. (Bug #68180, Bug #16222630)
• The Perl version of mysql_install_db mishandled some error messages. (Bug #68118, Bug
#16197542)
• For arguments with fractional seconds greater than six decimals, SEC_TO_TIME() truncated, rather
than rounding as it should have. (Bug #68061, Bug #16093024)
• Queries with many values in a IN() clause were slow due to inclusion of debugging code in nondebugging builds. (Bug #68046, Bug #16078212)
References: See also: Bug #58731, Bug #11765737.
• ALTER TABLE tbl_name ADD COLUMN col_name TIMESTAMP DEFAULT CURRENT_TIMESTAMP
ON UPDATE CURRENT_TIMESTAMP inserted 0000-00-00 00:00:00 rather than the current
timestamp if the alteration was done in place rather than by making a table copy. (Bug #68040, Bug
#16076089)
• mysqld_safe used the nonportable -e test construct. (Bug #67976, Bug #16046140)
• Nonspatial indexes only support exact-match lookups for spatial columns, but the optimizer incorrectly
used range access in some cases, leading to incorrect results. (Bug #67889, Bug #15993693)
• For EXPLAIN DELETE and EXPLAIN UPDATE the possible_keys column listed all indexes, not just
the applicable indexes. (Bug #67830, Bug #15972078)
• MySQL failed to build if configured with WITH_LIBWRAP enabled. (Bug #67018, Bug #16342793)
• CMake did not check whether the system zlib had certain functions required for MySQL, resulting in
build errors. Now it checks and falls back to the bundled zlib if the functions are missing. (Bug #65856,
Bug #14300733)
• If a dump file contained a view with one character set and collation defined on a view with a different
character set and collation, attempts to restore the dump file failed with an “illegal mix of collations” error.
(Bug #65382, Bug #14117025)
• If the server was started without a --datadir option, SHOW VARIABLES could show an empty value for
the datadir system variable. (Bug #60995, Bug #12546953)
• For debug builds, some queries with SELECT ... FROM DUAL nested subqueries raised an assertion.
(Bug #60305, Bug #11827369)
• The --log-slow-admin-statements and --log-slow-slave-statements
command options now are exposed at runtime as the log_slow_admin_statements and
log_slow_slave_statements system variables. Their values can be examined using SHOW
VARIABLES. The variables are dynamic, so their values can be set at runtime. (The options were
actually replaced by the system variables, but as system variables can be set at server startup, no option
functionality is lost.) (Bug #59860, Bug #11766693)
• UNION ALL on BLOB columns could produce incorrect results. (Bug #50136, Bug #11758009)
• An out-of-memory condition could occur while handling an out-of-memory error, leading to recursion in
error handling. (Bug #49514, Bug #11757464)
129
MySQL 5.6 Release Notes
• The REPLACE() function produced incorrect results when a user variable was supplied as an argument
and the operation was performed on multiple rows. (Bug #49271, Bug #11757250)
• UNION type conversion could incorrectly turn unsigned values into signed values. (Bug #49003, Bug
#11757005)
• Setting max_connections to a value less than the current number of open connections caused the
server to exit. (Bug #44100, Bug #11752803)
• The optimizer used loose index scan for some queries for which this access method is inapplicable. (Bug
#42785, Bug #11751794)
• View access in low memory conditions could raise a debugging assertion. (Bug #39307, Bug
#11749556)
Changes in MySQL 5.6.10 (2013-02-05, General Availability)
Beginning with MySQL 5.6.10, MySQL Enterprise Edition is available for MySQL 5.6. Specifically, MySQL
Enterprise 5.6.10 includes these components previously available only in MySQL 5.5: MySQL Enterprise
Security (PAM and Windows authentication plugins), MySQL Enterprise Audit, and MySQL Thread Pool.
For information about these features, see MySQL Enterprise Edition. To learn more about commercial
products, see http://www.mysql.com/products/.
Known limitations of this release:
On Microsoft Windows, when using the MySQL Installer to install MySQL Server 5.6.10 on a host with an
existing MySQL Server of a different version (such as 5.5.30), that also has a different license (community
versus commercial), you must first update the license type of the existing MySQL Server. Otherwise,
MySQL Installer will remove MySQL Server(s) with different licenses from the one you chose with MySQL
Server 5.6.10.
On Microsoft Windows 8, updating a community release to a commercial release requires you to manually
restart the MySQL service after the update.
• Functionality Added or Changed
• Bugs Fixed
Functionality Added or Changed
• InnoDB: When compressed tables were used, the calculation to compute memory usage
within the buffer pool was complex because the compressed pages could be smaller than
16KB or the user-specified page size. Although this information can be retrieved from the
INFORMATION_SCHEMA.INNODB_BUFFER_PAGE table, that operation is expensive. The following new
status variables help to simplify calculations involving buffer pool memory usage:
• Innodb_buffer_pool_bytes_data, to supplement Innodb_buffer_pool_pages_data.
• Innodb_buffer_pool_bytes_dirty, to supplement Innodb_buffer_pool_pages_dirty.
(Bug #15842637)
• Replication: An Auto_Position column has been added to the output generated by SHOW SLAVE
STATUS. The value of this column shows whether replication autopositioning is in use. If autopositioning
is enabled—that is, if MASTER_AUTO_POSITION = 1 was set by the last successful CHANGE MASTER
TO statement that was executed on the slave—then the column's value is 1; if not, then the value is 0.
(Bug #15992220)
130
MySQL 5.6 Release Notes
• In RPM packages built for Unbreakable Linux Network, libmysqld.so now has a version number.
(Bug #15972480)
• Error messages for ALTER TABLE statement using a LOCK or ALGORITHM value not supported for
the given operation were very generic. The server now produces more informative messages. (Bug
#15902911)
• If a client with an expired password connected but old_passwords was not the value required
to select the password hashing format appropriate for the client account, there was no way for the
client to determine the proper value. Now the server automatically sets the session old_passwords
value appropriately for the account authentication method. For example, if the account uses the
sha256_password authentication plugin, the server sets old_passwords=2. (Bug #15892194)
• The validate_password_policy_number system variable was renamed to
validate_password_policy. (Bug #14588121)
• In JSON-format EXPLAIN output, the attached_condition information for subqueries now includes
select# to indicate the relative order of subquery execution. (Bug #13897507)
• The following changes were made to the sandbox mode that the server uses to handle client
connections for accounts with expired passwords:
• There is a new disconnect_on_expired_password system variable (default: enabled). This
controls how the server treats expired-password accounts.
• Two flags were added to the C API client library: MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS
for mysql_options() and CLIENT_CAN_HANDLE_EXPIRED_PASSWORDS for
mysql_real_connect(). Each flag enables a client program to indicate whether it can handle
sandbox mode for accounts with expired passwords.
MYSQL_OPT_CAN_HANDLE_EXPIRED_PASSWORDS is enabled for mysqltest unconditionally, for
mysql in interactive mode, and for mysqladmin if the first command is password.
For more information about how the client-side flags interact with
disconnect_on_expired_password, see Password Expiration and Sandbox Mode. (Bug #67568,
Bug #15874023)
Bugs Fixed
• Important Change; Replication: The lettercasing used for displaying UUIDs in global transaction
identifiers was inconsistent. Now, all GTID values use lowercase, including those shown in the
Retrieved_Gtid_Set and Executed_Gtid_Set columns from the output of SHOW SLAVE STATUS.
(Bug #15869441)
• Performance; InnoDB: Some data structures related to undo logging could be initialized unnecessarily
during a query, although they were only needed under specific conditions. (Bug #14676084)
• Performance; InnoDB: Optimized read operations for compressed tables by skipping redundant tests.
The check for whether any related changes needed to be merged from the insert buffer was being called
more often than necessary. (Bug #14329288, Bug #65886)
• Performance; InnoDB: Immediately after a table was created, a query against it would not use a loose
index scan. The same query might use a loose index scan following an ALTER TABLE on the table. The
fix improves the accuracy of the cost estimate for queries involving the grouping functions min() and
max(), and prevents the query plan from being changed by the ALTER TABLE statement. (The more
stable query plan might or might not use a loose index scan.) (Bug #14200010)
131
MySQL 5.6 Release Notes
• InnoDB: When the primary key of a table includes a column prefix, and a full-text index is defined on
the table, a full-text search resulted in an unnecessary warning being written to the error log. This fix
suppresses the unnecessary warning. (Bug #16169411)
• InnoDB: In online DDL operations, a DROP FOREIGN KEY clause was not allowed in an ALTER TABLE
statement that also performed any of the following:
• Adding or dropping a column.
• Adding or dropping a primary key index.
• Making a column NULL or NOT NULL.
• Reordering columns.
• Changing the ROW_FORMAT or KEY_BLOCK_SIZE properties.
(Bug #16095573, Bug #68019)
• InnoDB: Some Valgrind warnings were issued during shutdown, while cleaning up a background thread
that handles optimization of tables containing FULLTEXT indexes. (Bug #15994393)
• InnoDB: During an online DDL operation, changing a column from nullable to NOT NULL could succeed
or fail differently depending on whether the ALTER TABLE statement used ALGORITHM=INPLACE
or ALGORITHM=COPY. An operation with ALGORITHM=COPY would succeed even if the column
contained NULL values, while an operation with ALGORITHM=INPLACE failed because of the possibility
that the column contained NULL values. Now, making a column NOT NULL in combination with the
ALGORITHM=INPLACE clause is allowed, but only if the sql_mode configuration option includes the
STRICT_TRANS_TABLES or STRICT_ALL_TABLES setting. If the ALGORITHM clause is not specified
with the ALTER TABLE statement, the online DDL operation will use ALGORITHM=INPLACE if possible,
or ALGORITHM=COPY if not. (Bug #15961327)
• InnoDB: Under certain circumstances, an InnoDB table was reported as corrupted after import
using ALTER TABLE ... IMPORT TABLESPACE. The problem was accompanied by one of these
messages:
Warning
error
: InnoDB: The B-tree of index "PRIMARY" is corrupted.
: Corrupt
or:
Warning
error
: InnoDB: The B-tree of index "GEN_CLUST_INDEX" is corrupted.
: Corrupt
This issue occurred intermittently, and primarily affected large tables. The REPAIR TABLE statement
would fix the problem reported by the error message. (Bug #15960850, Bug #67807)
• InnoDB: Names of indexes being created by an online DDL operation were being displayed incorrectly
in INFORMATION_SCHEMA tables while the operation was in progress. This fix ensures the table names
have the leading 0xff byte stripped off for INFORMATION_SCHEMA queries. This change affects the
columns:
• innodb_buffer_page.index_name
• innodb_buffer_page_lru.index_name
• innodb_cmp_per_index.index_name
132
MySQL 5.6 Release Notes
• innodb_cmp_per_index_reset.index_name
• innodb_locks.lock_index
• innodb_sys_indexes.name
(Bug #15946256)
• InnoDB: ALTER TABLE statements using the online DDL feature could cause Valgrind warnings. (Bug
#15933178)
• InnoDB: If an online DDL operation to add a unique index failed, because duplicate items were
created by concurrent DML during the online DDL operation, the ALTER TABLE operation failed
with the wrong error type. It returned ER_INDEX_CORRUPT; now it returns the new error code
ER_DUP_UNKNOWN_IN_INDEX. (It does not return ER_DUP_KEY, because the duplicate key value is not
available to be reported when this condition occurs.) (Bug #15920713)
• InnoDB: During an online DDL operation to add a unique index, DML operations that created duplicate
values could fail with an ER_DUP_KEY error even though the index had not been made visible yet.
(There was a brief time window when this condition could occur.) The fix causes the index creation
operation to fail instead, if the index would be invalid because of duplicate entries produced by
concurrent DML. (Bug #15920445)
• InnoDB: Specifying an innodb_log_file_size value of 4GB or larger was not possible on 64-bit
Windows systems. This issue only affected debug builds. (Bug #15882860)
• InnoDB: If the server crashed near the end of an online DDL ALTER TABLE statement, a subsequent
CHECK TABLE statement using the EXTENDED clause could cause a serious error. (Bug #15878013)
• InnoDB: Creating an index on a CHAR column could fail for a table with a character set with varying
length, such as utf8, if the table was created with the ROW_FORMAT=REDUNDANT clause. (Bug
#15874001)
• InnoDB: This fix ensures that in case of a serious unhandled error during an ALTER TABLE operation
that copies the original table, any data that could be needed for data recovery is preserved, in tables
using names of the form #sql-ib-table_id or #mysql50##sql-ib-table_id. (Bug #15866623)
• InnoDB: The status variable Innodb_buffer_pool_read_ahead_evicted could show an
inaccurate value, higher than expected, because some pages in the buffer pool were incorrectly
considered as being brought in by read-ahead requests. (Bug #15859402, Bug #67476)
• InnoDB: An online DDL operation to add a primary key to a table could encounter a serious error if the
table also had an index on a column prefix of a BLOB column.
This fix suspends the background purge operation while a table is being rebuilt by an ALTER TABLE
statement, if any rows containing off-page columns would be removed. Currently, to avoid excessive
space usage during the online DDL operation, avoid these types of concurrent DML operations until the
ALTER TABLE is finished:
• DELETE of rows that contain off-page columns.
• UPDATE of primary key columns in rows that contain off-page columns.
• UPDATE of off-page columns.
(Bug #14827736)
133
MySQL 5.6 Release Notes
• InnoDB: The server could halt with an assertion error when creating an index on a column prefix for a
column using a multibyte character set:
InnoDB: Assertion failure in thread thread_num in file row0merge.cc line 465
InnoDB: Failing assertion: len == ifield-<fixed_len
(Bug #14753402)
• InnoDB: The server could halt with an assertion error while creating an index:
InnoDB: Assertion failure in thread thread_num in file row0merge.cc line 465
This issue affected tables with a combination of ROW_FORMAT=REDUNDANT off-page columns, and an
index on a column prefix. (Bug #14753402)
• InnoDB: A regression introduced by the fix for Bug#14100254 would result in a “!BPAGE>FILE_PAGE_WAS_FREED” assertion. (Bug #14676249)
• InnoDB: INFORMATION_SCHEMA tables with InnoDB metadata, such as innodb_sys_tablestats,
displayed nonalphanumeric characters in the names of tables using an encoded format, for example with
@0024 instead of $. (Bug #14550145)
• InnoDB: If the value of innodb_force_recovery was less than 6, opening a corrupted table might
loop forever if a corrupted page was read when calculating statistics for the table. Information about
the corrupted page was written repeatedly to the error log, possibly causing a disk space issue. The fix
causes the server to halt after a fixed number of failed attempts to read the page. To troubleshoot such a
corruption issue, set innodb_force_recovery=6 and restart. (Bug #14147491, Bug #65469)
• InnoDB: With a large value for innodb_buffer_pool_size, and
innodb_buffer_pool_instances set greater than 1, pages were being incorrectly evicted from the
buffer pool. (Bug #14125092)
• InnoDB: Corruption of the innodb_ft_user_stopword_table table could cause a server exit. (Bug
#67960, Bug #16038656)
• Partitioning: Partition pruning is now enabled for tables using a storage engine that provides automatic
partitioning, such as the NDB storage engine, but which are explicitly partitioned. Previously, pruning
was disabled for all tables using such a storage engine, whether or not the tables had explicitly defined
partitions.
In addition, as part of this fix, explicit partition selection is now disabled for tables using a storage engine
(such as NDB) that provides automatic partitioning. (Bug #14827952)
References: See also: Bug #14672885.
• Replication: When using GTID-based replication, and whenever a transaction was executed on
the master but was not sent to the slave because the slave already had a transaction with that ID,
semisynchrononous replication timed out. One case in which this could happen was during a failover
operation where the new master started behind the new slave. (Bug #15985893)
• Replication: An unnecessary flush to disk performed after every transaction when using FILE as the
replication info repository type could degrade performance. Now this is done only when both data and
relay log info is stored in (transactional) tables. (Bug #15980626)
• Replication: Issuing START SLAVE UNTIL SQL_BEFORE_GTIDS = gtid_set, where gtid_set
covered a large number (tens or hundreds of millions) of transactions, could cause the server to hang.
(Bug #15968413)
134
MySQL 5.6 Release Notes
• Replication: When a slave was started using --skip-innodb and replication info file repositories
(FILE being the default for both --relay-log-info-repository and --master-inforepository), replication was incorrectly stopped. However, if the slave is using file repositories and not
currently migrating between info repositories, replication should be able to work without issues. Now the
server ignores errors raised when trying to open table info repositories in such conditions.
In addition, binary log initialization was not performed correctly when starting the slave with --skipinnodb, which caused the --log-bin option to be ignored. (Bug #15956714, Bug #67798, Bug
#15971607)
• Replication: When temporary and persistent tables, or temporary tables using different storage engines,
are dropped in a single statement, this statement is actually written as two statements to the binary log,
each represented by its own log event. When gtid_mode is ON, each DDL event must have a GTID;
however, in such cases, the statement dropping the temporary table was uncommitted, which meant that
it was not given its own GTID.
Now, when a DDL statement dropping a temporary table and a table that is persistent, or that uses
a different storage engine, is separated in the manner just described, and the resulting logged
statement affecting only the temporary table does not implicitly commit, a commit is forced so that the
corresponding log event has own unique GTID. (Bug #15947962)
• Replication: Semisynchronous replication did not work correctly with GTIDs enabled. (Bug #15927032)
References: See also: Bug #14737388.
• Replication: When used on a binary log that had been written by a GTID-enabled server,
mysqlbinlog did not correctly handle transactions left unclosed by the omission of statements that
were ignored when the --database option was employed.
Now, whenever mysqlbinlog --database reads a GTID log event, it checks to see whether there is
an unclosed transaction, and if so, issues a commit. (Bug #15912728)
• Replication: When GTIDs were enabled, the automatic dropping of a temporary table when a client
disconnected did not always generate a GTID. Now each logged DROP TABLE statement, including any
generated by the server, is guaranteed to have its own GTID. (Bug #15907504)
• Replication: When a binary log is replayed on a server (for example, by executing a command like
mysqlbinlog binlog.000001 | mysql), it sets a pseudo-slave mode on the client connection used,
so that the server can read binary log and apply binary log events correctly. However, the pseudo-slave
mode was not disabled after the binary log dump was read, which caused unexpected filtering rules to
be applied to SQL statements subsequently executed on the same connection. (Bug #15891524)
• Replication: After dropping a column from the slave's version of a table, then altering the same column
of this table on the master (so that a type conversion would have been required had the column not been
droppped on the slave), inserts into this table caused replication to fail. (Bug #15888454)
• Replication: Use of sql_slave_skip_counter is not compatible with GTID-based replication.
Setting this variable to a nonzero value is now disallowed whenever --gtid-mode = ON, and
attempting to do so fails with an error. (Bug #15833516)
• Replication: During mysqld shutdown, global GTID variables were released before it was made certain
that all plugins had stopped using them. (Bug #14798275)
• Replication: MASTER_POS_WAIT() could hang or return -1 due to invalid updates by the slave SQL
thread when transactions were skipped by the GTID protocol. (Bug #14775893)
References: See also: Bug #15927032.
135
MySQL 5.6 Release Notes
• Replication: Trying to execute a Stop event on a multi-threaded slave could cause unwanted updates to
the relay log, leading the slave to lose synchronization with the master. (Bug #14737388)
• Replication: Names of databases in binary log query log events were not properly checked for length.
(Bug #14636219)
• Replication: Issuing START SLAVE concurrently with setting sql_slave_skip_counter or
slave_net_timeout could cause a deadlock. (Bug #14236151)
• Replication: When using statement-based replication, and where the master and the slave used
table schemas having different AUTO_INCREMENT columns, inserts generating AUTO_INCREMENT
values logged for a given table on the master could be applied to the wrong table on the slave. (Bug
#12669186)
• Replication: Repeated execution of CHANGE MASTER TO statements using invalid MASTER_LOG_POS
values could lead to errors and possibly a crash on the slave. Now in such cases, the statement fails
with a clear error message. (Bug #11764602, Bug #57454)
• Microsoft Windows: Dynamic file names (with colons) are no longer allowed. Static file names using
the Alternate Data Stream (ADS) NTFS functionality of Microsoft Windows may continue to be used.
(Bug #11761752)
• Oracle RPM packages were unusable by yum due to issues with the obsoletes line in the .spec file
causing yum to interpret the package as obsoleting itself. (Bug #16298542)
• During client connection processing, the server now performs password-expiration checking after SSL
checks. (Bug #16103348)
• The plugin logging routine mishandled its argument, resulting in undefined behavior. (Bug #16002890)
• A buffer-handling problem in yaSSL was fixed. (Bug #15965288)
• Within a stored procedure, executing a multiple-table DELETE statement that used a very long table alias
could cause the server to exit. (Bug #15954896)
• Metadata locking and table definition cache routines did not always check length of names passed to
them. (Bug #15954872)
• In the absence of a FULLTEXT index on an InnoDB table, a full-text query with COUNT(*) could raise an
assertion. (Bug #15950531)
• In certain rare cases, a query using UpdateXML() could cause the server to crash. (Bug #15948580)
References: See also: Bug #13007062.
• Very long table aliases in queries could cause the server to exit. (Bug #15948123)
• An online DDL operation that dropped an index could proceed despite not having sufficient locks on the
table. This issue could cause a serious error, although the error was only observed in debug builds. (Bug
#15936065)
• A comment added to mysqldump output for the --set-gtid-purged option was malformed and
caused a syntax error when the dump file was reloaded. (Bug #15922502)
References: See also: Bug #14832472.
• Contention in the thread pool during kill processing could lead to a Valgrind panic. (Bug #15921866)
• Several OpenSSL-related memory leaks were fixed. (Bug #15921729)
136
MySQL 5.6 Release Notes
• The ALTER TABLE statement can now use the LOCK=NONE clause, allowing online DDL with concurrent
DML, for child tables containing foreign key constraints. (Bug #15912214)
• Very long database names in queries could cause the server to exit. (Bug #15912213, Bug #16900358)
• AES_DECRYPT() and AES_ENCRYPT() had memory leaks when MySQL was compiled using
OpenSSL. (Bug #15909183)
• Several OpenSSL-related Valgrind warnings were corrected. (Bug #15908967)
• An ALTER TABLE with the ADD PRIMARY KEY or ADD UNIQUE INDEX clause could encounter a
serious error if the columns for the primary key or unique index contained duplicate entries. This error
occurred intermittently, depending on how the rows were physically distributed across index blocks. (Bug
#15908291)
• Rows_log_event allocated one too few bytes for the row buffer. (Bug #15890178)
• The Performance Schema normally ignores temporary table events. User-defined temporary tables are
truncated by being re-created, but the Performance Schema did not recognize re-created temporary
tables as being temporary and raised an assertion. (Bug #15884836)
• Several code issues identified by Fortify were corrected. (Bug #15884324)
• In debug builds, the server could not start on 64-bit Windows systems when a value of 16 GB or higher
was specified for innodb_buffer_pool_size. Non-debug builds would likely have subtler issues,
such as memory being allocated for the buffer pool but not used, or read requests overlooking pages
already cached in the buffer pool.
On 32-bit Windows systems, the value of innodb_buffer_pool_instances is increased
if necessary so that no buffer pool instance is larger than 1.3 GB, due to system limitations on
memory allocation. This automatic adjustment needed for 32-bit Windows systems was incorrectly
applied to 64-bit systems also; for systems with 16 GB or larger buffer pools, the adjusted value of
innodb_buffer_pool_instances would exceed the upper limit of 64, causing an assertion error in
debug builds. (Bug #15883071)
• A heavy workload of online DDL and concurrent DML on a table on a master server could cause errors
as the changes were replicated to slave servers. For example, processing a DROP COLUMN operation
at the same time as queries referring to the dropped column could cause errors on slave servers if the
statements finished in a different order than on the master. (Bug #15878880)
• Complex IN subqueries could cause the server to exit. (Bug #15877738)
• In some cases, a cost value was printed to Optimizer Trace output without being initialized, resulting in
incorrect output. (Bug #15877453)
• Some queries, if used as prepared statements, caused the server to exit if an error occurred. (Bug
#15877062)
• If an error occurred during the final phase of an online DDL operation, some cached metadata about
the table might not be restored to its original state. This issue typically affected operations that renamed
a column, and also dropped and re-created an index on that column, in the same ALTER TABLE
statement. This issue did not affect operations that reorganize the clustered index of the table, such as
adding a new primary key. (Bug #15866734)
• The optimizer's cost-based choice between IN -> EXISTS subquery transformation and subquery
materialization was sometimes incorrect if the IN predicate was OR-ed with some other predicate. (Bug
#15866339)
137
MySQL 5.6 Release Notes
References: See also: Bug #13111584.
• The session_connect_attrs Performance Schema table displayed extraneous information. (Bug
#15864703)
• For the LooseScan semi-join strategy, the optimizer could rely on an uninitialized variable. (Bug
#15849654)
• It was possible to expire the password for an account even if the account is authenticated by an
authentication plugin that does not support password expiration. (Bug #15849009)
• If loose index scan was used on a query with descending order, the result set contained NULL values
instead of the correct values. (Bug #15848665)
• For debug builds, an assertion could be raised when: 1) A view was based on a MEMORY table; 2) The
table was altered to drop some column in use by the view; 3) A SELECT was done on the view with
binary logging disabled. (Bug #15847447)
• If the server shut down unexpectedly, the presence of an InnoDB table with 1018 columns (very close to
the upper limit of 1020 columns) could cause an assertion error during server restart:
InnoDB: Failing assertion: table->n_def == table->n_cols - 3
(Bug #15834685)
• Subqueries with COUNT(DISTINCT ...)) could cause the server to exit. (Bug #15832620)
References: See also: Bug #11750963.
• Setting the validate_password_length system variable did not take into account that the minimum
value is a function of several other related system variables. Now the server will not set the value less
than the value of this expression:
validate_password_number_count
+ validate_password_special_char_count
+ (2 * validate_password_mixed_case_count)
(Bug #14850601)
• GRANT ... IDENTIFIED BY could fail to flush the privileges. (Bug #14849959)
• When the server reads the mysql.user table, it now checks for invalid native and old-native password
hashes and ignores accounts with invalid hashes. (Bug #14845445)
• The validate_password plugin did not check certain passwords. (Bug #14843970)
• mysqladmin did not properly process commands for users with expired passwords. (Bug #14833621)
• MySQL could encounter an error during shutdown on Windows XP or earlier systems. This issue did
not affect systems running Windows Vista or higher, which use atomic condition variables to represent
Windows Events. (Bug #14822849)
• An issue with locking order for the system tables and the InnoDB data dictionary could lead to an internal
deadlock within MySQL. (Bug #14805484)
• Temporary table creation during execution of INFORMATION_SCHEMA queries could result in Valgrind
warnings. (Bug #14801497)
138
MySQL 5.6 Release Notes
• When used with an XPath expression that contained the output of a stored function, ExtractValue()
failed with the error Only constant XPATH queries are supported. (Bug #14798445, Bug
#67313)
• The server could halt with an assertion error due to a recently added error code:
InnoDB: unknown error code 1502
InnoDB: Assertion failure in thread thread_num in file row0mysql.cc line 683
mysqld got signal 6 ;
Now, the server returns the error code DB_DICT_CHANGED to the client in this case. (Bug #14764015)
• The clause ALGORITHM=INPLACE clause in an ALTER TABLE statement for a partitioned table could
lead to consistency issues if a crash occurred while changes were applied to some of the underlying
tables but not all. This fix prohibits the ALGORITHM=INPLACE clause for DDL operations on partitioned
tables. (Bug #14760210)
• The sha256_password authentication plugin requires that the client connect either using SSL or have
RSA enabled. When neither condition was met, an uninformative error message was produced. Now the
error message is more informative. (Bug #14751925)
• Queries that used grouping failed when executed using a cursor if the optimizer processed the grouping
using a temporary table. (Bug #14740889)
• XA START had a race condition that could cause a server crash. (Bug #14729757)
• The server could exit when the MyISAM storage engine (rather than MEMORY) was used to materialize a
derived table. (Bug #14728469)
• The server now logs warnings at startup if the file specified for the
validate_password_dictionary_file system variable violates constraints on valid password file
contents. (Bug #14588148)
• Calculations involving self-intersecting polygons caused an assertion to be raised. (Bug #14503584)
• At startup, some InnoDB boolean system variables could be set to 1 or 0, but not ON or OFF.
These included innodb_file_per_table, innodb_force_load_corrupted, and
innodb_large_prefix. (Bug #14494893)
• Output generated with mysqldump --routines could produce syntax errors when reloaded. (Bug
#14463669)
• If ALTER TABLE was killed, the server could report ER_QUERY_INTERRUPTED even if the alterations
had been made successfully. This is misleading to the user. Also, the statement would not be written to
the binary log, leading to incorrect replication (Bug #14382643)
• With the ONLY_FULL_GROUP_BY SQL mode enabled, executing a stored function twice that contains an
SQL query that is not valid with that mode enabled caused the server to exit. (Bug #13996639)
• Preloading of client plugins specified with the LIBMYSQL_PLUGINS environment variable could fail
unless the plugins were located in the hardwired default plugin directory. The C API now checks during
plugin preloading for a LIBMYSQL_PLUGIN_DIR environment variable which can be set to the path
name of the directory in which to look for client plugins.
In addition, for explicit client plugin loading, the mysql_load_plugin() and
mysql_load_plugin_v() C API functions have been modified to use the LIBMYSQL_PLUGIN_DIR
value if it exists and the --plugin-dir option was not given. If --plugin-dir is given,
139
MySQL 5.6 Release Notes
mysql_load_plugin() and mysql_load_plugin_v() ignore LIBMYSQL_PLUGIN_DIR. (Bug
#13994567, Bug #18110355)
• The parser failed to return an error for some invalid UNION constructs. (Bug #13992148)
• Due to a thread race condition, the server could exit while attempting to read the Performance Schema
threads.PROCESSLIST_INFO column. (Bug #68127, Bug #16196158)
• Some messages written by the server to the error log referred to the deprecated --log-slowqueries option rather than the --slow-query-log option. Similarly, the server referred to the
deprecated --log option rather than the --general-log-file and --log-output options. (Bug
#67892, Bug #15996571)
• Autosizing of Performance Schema parameters could result in settings that caused excessive CPU use.
(Bug #67736, Bug #15927744)
• For single-table DELETE or UPDATE statements, EXPLAIN displayed a type value of ALL (full-table scan
access method) even if the optimizer chose to scan the table by an index access method. Now the type
value is displayed as index. (Bug #67637, Bug #15892875)
• The optimizer could choose an IN-to-EXISTS transformation for subquery execution in some cases
when subquery materialization would be cheaper. (Bug #67511, Bug #15848521)
• It is not permitted to use CREATE TABLE to create an NDB table with user-defined partitioning and a
foreign key. However, it was possible to create an NDB table with a foreign key, then add partitioning
to it using ALTER TABLE, thus creating a table which was impossible to back up or restore using
mysqldump. Now the prohibition is enforced consistently. (Bug #67492, Bug #15844519)
• The optimizer sometimes chose a nonoptimimal range scan strategy when a query included a LIMIT
clause. (Bug #67432, Bug #15829358)
• Attempting to perform an in-place upgrade from MySQL 5.1 to 5.6 causes the server to exit due to a
mismatch between the privilege structures in the two series. (This is not a supported operation, but the
server should not exit ungracefully.) (Bug #67319, Bug #14826854)
• mysqldump could fail to dump all tables in the mysql database. (Bug #67261, Bug #14771252)
• Full-text searches in InnoDB tables could return incorrect results. (Bug #67257, Bug #14771282)
• The Performance Schema normally ignores temporary table events, but sometimes failed to properly
identify a table as temporary and consequently recorded events for the table. (Bug #67098, Bug
#14756887)
• The mysql client could mishandle the delimiter command if it occurred on a line during which mysql
was looking for the end of a quoted string. (Bug #64135, Bug #13639125)
• DECIMAL multiplication operations could produce significant inaccuracy. (Bug #45860, Bug #11754279)
Changes in MySQL 5.6.9 (2012-12-11, Release Candidate)
• Installation Notes
• Functionality Added or Changed
• Bugs Fixed
Installation Notes
• The --random-passwords option for mysql_install_db is now supported for MySQL install
operations (not upgrades) using Solaris PKG packages.
140
MySQL 5.6 Release Notes
Functionality Added or Changed
• Incompatible Change; Replication: A number of variable and other names relating to GTID-based
replication have been changed, with a view to making these names more appropriate and meaningful.
The old names are no longer supported.
The features so renamed are shown in the following list:
• The --disable-gtid-unsafe-statements server option has been renamed --enforce-gtidconsistency; the disable_gtid_unsafe_statements system variable has been renamed
enforce_gtid_consistency.
• The gtid_done server system variable has been renamed gtid_executed.
The gtid_lost server system variable has been renamed gtid_purged; in addition, this variable is
no longer read-only.
• The SQL_THREAD_WAIT_AFTER_GTIDS() function has been renamed
WAIT_UNTIL_SQL_THREAD_AFTER_GTIDS().
For more information, see Replication with Global Transaction Identifiers, and Global Transaction ID
Options and Variables. (Bug #14775984)
• Microsoft Windows: Windows Vista, Windows Server 2008, and newer support native symlinking using
the mklink command. This makes the MySQL Server implementation of database symbolic links using
.sym files redundant, so that mechanism is now deprecated and will be removed in a future MySQL
release. See Using Symbolic Links for Databases on Windows.
• For client connections restrictd by the server because the client account password is expired, the server
now permits SET PASSWORD only if the account named in the statement matches the account used by
the client. (Bug #14807074)
References: See also: Bug #14698309.
• The server now provides thread information (for SHOW PROCESSLIST) to indicate the progress of inplace ALTER TABLE operations:
• preparing for alter table
The server is preparing to execute an in-place ALTER TABLE.
• altering table
The server is in the process of executing an in-place ALTER TABLE.
• committing alter table to storage engine
The server has finished an in-place ALTER TABLE and is committing the result.
(Bug #14790408)
• InnoDB automatically extends each secondary index by appending the primary key columns to it.
Previously, the optimizer did not take into account the primary key columns of the extended secondary
index when determining how and whether to use that index. Now the optimizer takes the primary key
columns into account, which can result in more efficient query execution plans and better performance.
The optimizer can use extended secondary keys for ref, range, and index_merge index access, for
loose index scans, for join and sorting optimization, and for MIN()/MAX() optimization.
141
MySQL 5.6 Release Notes
The new use_index_extensions flag of the optimizer_switch system variable permits control
over whether the optimizer takes the primary key columns into account when determining how to use an
InnoDB table's secondary indexes. By default, use_index_extensions is enabled. To check whether
disabling use of index extensions will improve performance, use this statement:
SET optimizer_switch = 'use_index_extensions=off';
For more information, see Use of Index Extensions. (Bug #62025, Bug #12814559, Bug #56714, Bug
#11763940)
• mysqld now writes dates to the error log in ISO (YYYY-MM-DD hh:mm:ss) format. It also includes its
process ID following the date. Thanks to Davi Arnaut for the patch. (Bug #56240, Bug #11763523)
Bugs Fixed
• Incompatible Change: The THREAD_ID column in Performance Schema tables was widened from INT
to BIGINT to accommodate 64-bit values.
Note
As a consequence of this change, the PROCESSLIST_ID column of the threads
table is now NULL for background threads. Previously, the value was 0 for
background threads.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate this change to the performance_schema database. (Bug #14664453)
• Incompatible Change: LAST_INSERT_ID(expr) did not work for expr values greater than the largest
signed BIGINT value. Such arguments now are accepted, with some consequences for compatibility
with previous versions:
• LAST_INSERT_ID() now returns a BIGINT UNSIGNED value, not a BIGINT (signed) value.
• LAST_INSERT_ID(expr) now returns an unsigned integer value, not a signed integer value.
• For AUTO_INCREMENT columns, negative values are no longer supported.
(Bug #20964, Bug #11745891)
• Incompatible Change: Connection ID (thread ID) values greater than 32 bits can occur on some
systems (such as busy or long-running 64-bit systems), causing these problems:
• Connection IDs written to the general query log and slow query log were incorrect. This was true for
logging to both files and tables.
• The CONNECTION_ID() function could return a value with a data type too small for values larger than
32 bits.
• The mysql_thread_id() and mysql_kill() C API functions did not handle ID values
larger than 32 bits. This could result in killing the wrong thread; for example, if you invoked
mysql_kill(mysql_thread_id()).
Connection IDs now are permitted to be 64-bit values when the server supports them (when built with
64-bit data types), which has these effects:
• Connection IDs are logged correctly to the general query log and slow query log.
142
MySQL 5.6 Release Notes
Note
This change involves a modification to the log tables, so after upgrading to this
release, you must run mysql_upgrade and restart the server.
• CONNECTION_ID() returns a data type appropriate for values larger than 32 bits.
• mysql_thread_id() is unchanged; the client/server protocal has only 4 bytes for the ID value. This
function returns an incorrect (truncated) value for connection IDs larger than 32 bits and should be
avoided.
mysql_kill() still cannot handle values larger than 32 bits, but to guard against killing the wrong
thread now returns an error in these cases:
• If given an ID larger than 32 bits, mysql_kill() returns a CR_INVALID_CONN_HANDLE error.
• After the server's internal thread ID counter reaches a value larger than 32 bits, it returns an
ER_DATA_OUT_OF_RANGE error for any mysql_kill() invocation and mysql_kill() fails.
To avoid problems with mysql_thread_id() and mysql_kill(), do not use them. To get the
connection ID, execute a SELECT CONNECTION_ID() query and retrieve the result. To kill a thread,
execute a KILL statement.
(Bug #19806, Bug #11745768, Bug #65715, Bug #14236124, Bug #44728, Bug #11753308)
• Important Change; InnoDB: A DML statement using the index merge access method could lock many
rows from the table, even when those rows were not part of the final result set. This fix reduces the
excessive locking by releasing the locks of unmatched rows. This optimization affects only transactions
with isolation level equal to or less strict than READ COMMITTED; it does not apply to transactions using
REPEATABLE READ or SERIALIZABLE isolation level. (Bug #14226171)
• Important Change; Replication: Statements involving the Performance Schema tables should not
be written to the binary log, because the content of these tables is applicable only to a given MySQL
Server instance, and may differ greatly between different servers in a replication topology. The database
administrator should be able to configure (INSERT, UPDATE, or DELETE) or flush (TRUNCATE TABLE)
performance schema tables on a single server without affecting others. However, when using replication
with GTIDs enabled (see Replication with Global Transaction Identifiers), warnings about unsafe
statements updating Performance Schema tables were elevated to errors, preventing the use of
performance_schema and GTIDs together.
Similar problems were encountered with replication and system logging tables when GTIDs were
enabled.
This fix introduces the concept of a nonreplicated or local table. Now when MySQL replication
encounters a table that is marked as local, updates to this table are ignored.
This fix defines as local the following tables, which are no longer replicated:
• All tables in the performance_schema database
• mysql.general_log
• mysql.slow_log
• mysql.slave_relay_log_info
143
MySQL 5.6 Release Notes
• mysql.slave_master_info
• mysql.slave_worker_info
Before this fix, statements using the performance_schema and other tables just listed were handled
by being marked as unsafe for replication, which caused warnings during execution; the statements were
nonetheless written to the binary log, regardless of the logging format in effect.
Existing replication behavior for tables in the INFORMATION_SCHEMA database is not changed by this
fix.
For more information, see MySQL Performance Schema. See also MySQL Server Logs, and Slave
Status Logs. For information about general and slow query log tables, see Selecting General Query and
Slow Query Log Output Destinations. (Bug #14741537)
• Important Change; Replication: Because running the server with GTIDs enabled prevented changes
to nontransactional tables, programs such as mysql_upgrade and mysql_install_db were unable
to operate on system tables that used the MyISAM storage engine and therefore could not function
correctly. Now, when running with --enforce-gtid-consistency (required whenever --gtidmode=ON), the server allows single statements on nontransactional tables. (Bug #14722659)
• Important Change; Replication: Formerly, the value of the Seconds_Behind_Master column
in the output of SHOW SLAVE STATUS was always set to NULL whenever the SQL thread or the
I/O thread was stopped. Now, this column is set to NULL only if the SQL thread is not running, or
if the I/O thread is not running following a check to determine whether or not the SQL thread has
processed all of the relay log. (If the SQL thread has finished processing and the I/O thread is running,
Seconds_Behind_Master is 0.) (Bug #12946333)
• Performance; InnoDB: The timing values for low-level InnoDB read operations were adjusted for
better performance with fast storage devices, such as SSD. This enhancement primarily affects read
operations for BLOB columns in compressed tables. (Bug #13702112, Bug #64258)
• InnoDB; Partitioning: Previously, when attempting to optimize one or more partitions of a partitioned
table that used a storage engine that does not support partition-level OPTIMIZE, such as InnoDB,
MySQL reported Table does not support optimize, doing recreate + analyze
instead, then re-created the entire table, but did not actually analyze it. Now in such cases, the
warning message is, Table does not support optimize on partitions. All partitions
will be rebuilt and analyzed. In addition, the entire table is analyzed after first being rebuilt.
(Bug #11751825, Bug #42822)
• InnoDB: The server could halt with an error when two kinds of operations happened simultaneously:
• A ROLLBACK of an inserted row that contained off-page columns.
• An online DDL operation involving a table of ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED
(that is, using the Barracuda file format) that rebuilt the table. For example, ADD/DROP COLUMN, ADD
PRIMARY KEY, change ROW_FORMAT.
(Bug #14842014)
• InnoDB: If the server crashed while rows were inserted into a table with a FULLTEXT index but before
the transaction was committed, an error could occur during the next startup:
InnoDB: Assertion failure in thread thread_num in file dict0dict.cc line 1019
(Bug #14826779)
144
MySQL 5.6 Release Notes
• InnoDB: The server could halt with an error when accessing an InnoDB table containing a FULLTEXT
index through the HANDLER statement. (Bug #14788710)
• InnoDB: A timeout error could occur on Windows systems when doing ALTER TABLE statements with
the DISCARD TABLESPACE or IMPORT TABLESPACE clauses, due to a temporary tablespace file
remaining in the file system. (Bug #14776799)
• InnoDB: InnoDB tables with FULLTEXT indexes could allocate memory for thread handles that was
never released, possibly leading to resource issues on Windows systems. (Bug #14759163)
• InnoDB: The server could halt with an assertion error for an ANALYZE TABLE operation, depending on
the structure of the table and its indexes:
InnoDB: Assertion failure in thread thread_num in file dict0dict.ic line 447
InnoDB: Failing assertion: pos < table->n_def
(Bug #14755452)
• InnoDB: During an online DDL operation that copies the table, the secondary index of the table could
become corrupted. (Bug #14753701)
• InnoDB: An online DDL operation for an InnoDB table incorrectly reported an empty value ('') instead
of the correct key value when it reported a duplicate key error for a unique index using an index prefix.
(Bug #14729221)
• InnoDB: If the server crashed after an online DDL CREATE INDEX operation, an error could occur while
rolling back incomplete transactions on the next startup:
InnoDB: error in sec index entry del undo in
...
InnoDB: Assertion failure in thread thread_num in file row0umod.cc line 559
(Bug #14707452)
• InnoDB: This fix improves the error handling when an ALTER TABLE operation adds a column beyond
the maximum number allowed for an InnoDB table. It also raises the maximum number of columns for
an InnoDB table from 1000 to 1020. (Bug #14705287)
• InnoDB: This fix makes MySQL more responsive to KILL QUERY statements when the query is
accessing an InnoDB table. (Bug #14704286)
• InnoDB: If the server crashed at a precise moment during an ALTER TABLE operation that rebuilt the
clustered index for an InnoDB table, the original table could be inaccessible afterward. An example of
such an operation is ALTER TABLE ... ADD PRIMARY KEY The fix preserves the original table if
the server halts during this operation. You might still need to rename the .ibd file manually to restore
the original table contents: in MySQL 5.6 and higher, rename from #sql-ib$new_table_id.ibd to
table_name.ibd within the database directory; prior to MySQL 5.6, the temporary file to rename is
table_name#1 or #2. (Bug #14669848)
• InnoDB: During an online DDL operation that rebuilt the table, a CHECK TABLE statement could report a
count mismatch for all secondary indexes. (Bug #14606472)
• InnoDB: After a FULLTEXT index was created and dropped from an InnoDB table, further ALTER
TABLE operations to add, drop, and rename columns could cause a serious error. Regression of bug
#13972248. (Bug #14504337)
145
MySQL 5.6 Release Notes
• InnoDB: If an ALTER TABLE statement failed while attempting to create a FULLTEXT index for an
InnoDB table, the server could halt with an assertion error while dropping the incomplete index. (Bug
#14504174)
• InnoDB: During shutdown, with the innodb_purge_threads configuration option set greater than 1,
the server could halt prematurely with this error:
mysqld got signal 11
A workaround was to increase innodb_log_file_size and set innodb_purge_threads=1.
The fix was backported to MySQL 5.5 and 5.1, although those versions do not have the
innodb_purge_threads configuration option so the error was unlikely to occur. (Bug #14234028)
• InnoDB: The server could halt with an error under some combinations of concurrent operations:
InnoDB: unknown error code 20
This issue originated during the 5.6 development cycle. It affected only transactions using the READ
COMMITTED andREAD UNCOMMITTED isolation levels. (Bug #13641662, Bug #12424846)
• InnoDB: This fix improves the error message when a foreign key constraint cannot be created. Instead
of referring to an inability to create a table with an auto-generated name, the message clearly states the
error:
ERROR 1215 (HY000): Cannot add foreign key constraint
Issuing a subsequent SHOW WARNINGS statement provides additional detail about any secondary
indexes that are required. (Bug #11745444, Bug #15324)
• Replication: If a table to be replicated had a FULLTEXT index, this index was not ruled out when
selecting the type of scan to be used in finding the next row, even though it cannot be used to find
the correct one. The row applier subsequently tried unsuccessfully to employ an index scan, causing
replication to fail. Now in such cases, indexes which do not provide for sequential access (such as
FULLTEXT) are not considered when determining whether to use a table, index, or hash scan for this
purpose. (Bug #14843764)
• Replication: Given a stored routine R in which the GTID_SUBTRACT() function was invoked: Once
GTID_SUBTRACT() returned NULL when called inside R, it continued to return NULL every time it was
called within R, for the remainder of the client session. (Bug #14838575)
• Replication: When using the GTID-aware master-slave protocol, the slave I/O thread used the wrong
position. When using GTIDs, the position is not normally used, but as a special case, the position was
used in addition to the GTID when the slave reconnected to the same master (even though this was not
necessary). This problem is fixed by making the GTID-aware master-slave protocol not use positions at
all any longer. (Bug #14828028)
• Replication: MySQL Enterprise Backup, mysqldump, and mysqlhotcopy could not be used with
a GTID-enabled MySQL Server, because they were unable to restore the server's GTID state and so
could not restore from any point in the binary log other than the very beginning.
As part of the fix for this problem, the gtid_purged system variable (formerly named gtid_lost) is
no longer read-only; now it is possible to add GTIDs to it when gtid_executed (formerly gtid_done)
is empty. (Bug #14787808)
• Replication: Restarting replication after the first binary log file was purged resulted in the error Got
fatal error 1236 from master when reading data from binary log: 'The slave
146
MySQL 5.6 Release Notes
is connecting using CHANGE MASTER TO MASTER_AUTO_POSITION = 1, but the master
has purged binary logs containing GTIDs that the slave requires.' This led GTIDbased replication to fail. (Bug #14756691)
• Solaris: Installation using Solaris packages ran mysql_install_db during upgrade operations (this
should occur only for new installations). (Bug #14747671, Bug #16534721)
• mysql_install_db failed to honor the --user option. (Bug #15866735)
• The optimizer could allocate insufficient memory when determining subquery execution strategies,
causing the server to exit. (Bug #14846866)
• The optimizer could raise an assertion when evaluating a range test against an IS NOT NULL condition.
(Bug #14843705)
• init_io_cache() used memset() to clear a mutex but passed the wrong mutex size. (Bug
#14838882)
• Creating an InnoDB table with a FULLTEXT index could encounter a serious error if the table name
contained nonalphanumeric characters. (Bug #14835178, Bug #16036699)
• Out-of-bounds reads could occur within filename_to_tablename(). (Bug #14834378)
• When a backup is taken using mysqldump on a server with global transaction IDs (GTIDs) enabled, the
dump file did not contain any GTID information. This eventually results in replicating the transactions
from the beginning of history when the backup is used to bring up a slave.
To enable control over GTID information written to the dump file, mysqldump now has a --set-gtidpurged option that indicates whether to add a SET @@global.gtid_purged statement to the output.
The following table shows the permitted option values. The default value is AUTO.
Value
Meaning
OFF
Add no SET statement to the output.
ON
Add a SET statement to the output. An error occurs if GTIDs are not enabled on the server.
AUTO
Add a SET statement to the output if GTIDs are enabled on the server.
(Bug #14832472)
• With LOCK TABLES in effect, CREATE TABLE IF NOT EXISTS ... LIKE could raise an assertion.
(Bug #14788976)
• An assertion could be raised executing INSERT, UPDATE, or DELETE after implicitly starting a READ
ONLY transaction in LOCK TABLES mode. (Bug #14788540)
• A query with a union and a join could crash the parser. (Bug #14786792, Bug #16076289)
• Attempting to read a utf16 file with LOAD DATA INFILE raised an assertion. (Bug #14786470)
• The automatic key generation part of derived table handling did not handle properly columns specified as
part of the VALUES() clause and caused an assertion to be raised. (Bug #14786324)
• Invalid memory reads could occur for queries that selected from a zero-length table name. (Bug
#14780820)
• SHOW PROCESSLIST output was not sorted in Id order. (Bug #14771006)
• For some SELECT statements, EXPLAIN could cause the server to exit. (Bug #14761894)
147
MySQL 5.6 Release Notes
• Attempting to create an auto-increment column in an InnoDB table with a NULL type attribute could
cause a serious error. (Bug #14758479)
• A memory leak occurred for attempts to use ALTER TABLE to set a default value for a tiny, medium, or
long BLOB or TEXT column. (Bug #14756206)
• An assertion was raised if ALTER TABLE was used to rename a column to same name as an existing
column while also reordering the renamed column using AFTER or FIRST. (Bug #14756089)
• An assertion could be raised if semi-join materialization was used to evaluate a NOT IN subquery. (Bug
#14751858)
• After issuing ALTER TABLE ... DISCARD TABLESPACE, an online DDL operation for the same table
could fail on Windows systems with an error: Got error 11 from storage engine. An ALTER
TABLE statement with the ALGORITHM=INPLACE clause could also create an empty .ibd file, making the
tablespace no longer “discarded”. (Bug #14735917)
• For some continuation handler nestings, continuation could occur at the wrong location. (Bug
#14724836)
• Starting the server with --bind-address and then setting host_cache_size to 0 could result in the
server stopping for certain kinds of client connections. (Bug #14689561)
• For UPDATE statements, EXPLAIN showed the total key length in the key_len column rather than the
length of the used key parts. (Bug #14682438)
• With index condition pushdown enabled, the optimizer could produce incorrect results for derived tables.
(Bug #14640176)
• SHOW PROFILE could be used to cause excessive server memory consumption. (Bug #14629232)
• The optimizer could incorrectly use a nonspatial index to optimize spatial operations, causing an
assertion to be raised. (Bug #14600994)
• Several problems with mysql_config_editor were fixed:
• There was no error message for write errors to the configuration file.
• The --all option is not supported for the remove command, but there was no warning message for
attempts to use remove --all.
• The --all option is not supported for the set command, but there was no warning message for
attempts to use set --all.
In addition, the --user, --password, and --host options now are supported for the remove
command. When present, the remove command removes only the requested values from the login path.
If none of them is given, remove removes the entire client login path. For example, this command
removes only the user value from the client login path rather than the entire client login path:
mysql_config_editor remove --login-path=client --user
(Bug #14505672, Bug #14545989, Bug #14545999)
• A LIKE pattern with too many '%' wildcards could cause a segmentation fault. (Bug #14303860)
• Previously, the events_statements_summary_by_digest Performance Schema table was a
summary grouped by the DIGEST column alone. Now this table contains a SCHEMA_NAME column and
the digest summary is grouped by the SCHEMA_NAME and DIGEST columns.
148
MySQL 5.6 Release Notes
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate this change into the performance_schema database. (Bug
#14075527)
• Query rewriting to scrub passwords for logging was done even if none of the associated logs were
enabled. Also, CREATE SERVER and ALTER SERVER are now rewritten as necessary. (Bug #14073554)
• CREATE TABLE ... SELECT could create a table with a column of type NULL, which when accessed
caused a server exit. (Bug #14021323, Bug #23280699)
• CHECK TABLE and REPAIR TABLE could crash if a MyISAM table had a corrupt key (.MYI) file. Now
the server produces an error. (Bug #13556441)
• CHECK TABLE and REPAIR TABLE could crash if a MyISAM table had a corrupt key (.MYI) file. Now
the server produces an error. (Bug #13556107, Bug #13556000)
• A “buffer too small” error message from the myisamchk command referred to the
myisam_sort_buffer_size configuration option, when it should have referred to
sort_buffer_size.
myisamchk now has a myisam_sort_buffer_size variable available as an alternative name to
sort_buffer_size. myisam_sort_buffer_size is preferable to sort_buffer_size because
its name corresponds to the myisam_sort_buffer_size server system variable that has a similar
meaning. sort_buffer_size should be considered deprecated. (Bug #11754894, Bug #46578)
• The host_cache Performance Schema table displayed some lines multiple times. This was not an
issue with the host cache itself, only with the table that provides information about the cache contents.
(Bug #67236, Bug #14764890)
• On OS X, reinitializing the query cache could cause the server to exit. Thanks to Davi Arnaut for the
patch. (Bug #67156, Bug #14741880)
• The server failed to use the query cache for queries in which a database or table name contained special
characters and the table storage engine was InnoDB. (Bug #64821, Bug #13919851)
• mysqld_safe ignored the value of the UMASK environment variable, leading to behavior different from
mysqld with respect to the access mode of created files. Now mysqld_safe (and mysqld_multi)
attempt to approximate the same behavior as mysqld. (Bug #57406, Bug #11764559)
• For dumps of the mysql database, mysqldump skipped the event table unless the --events option
was given. This no longer occurs. To skip the event table if that is desired, use the --ignore-table
option instead (Bug #55587, Bug #11762933)
• For MEMORY tables with HASH indexes, DELETE sometimes failed to delete all applicable rows. (Bug
#51763, Bug #11759445)
• On OS X, KILL could sometimes be unreliable. (Bug #37780, Bug #11748945)
Changes in MySQL 5.6.8 (2012-11-07, Release Candidate)
• Configuration Notes
• Installation Notes
• Security Notes
• Functionality Added or Changed
149
MySQL 5.6 Release Notes
• Bugs Fixed
Configuration Notes
• This release continues the process begun in MySQL 5.6.6 of making changes to the default values of
server parameters. The motivation for these changes is to provide better out-of-box performance and to
reduce the need for database administrators to change settings manually. These changes are subject to
revision in future releases as we gain feedback.
In some cases, a parameter has a different fixed default value. In other cases, the server autosizes a
parameter at startup using a formula based on other related parameters or server host configuration,
rather than using a fixed value. For example, the setting for host_cache_size is its previous default
of 128, adjusted up by an amount proportional to the value of max_connections. The idea behind
autosizing is that when the server has information available to make a decision about a parameter
setting likely to be better than a fixed default, it will.
The following table summarizes changes to defaults. For variables that are autosized, the main variable
description provides additional detail about the sizing algorithm. See Server System Variables, and
InnoDB Startup Options and System Variables. Any of these default settings can be overridden by
specifying an explicit value at server startup.
Parameter
Old Default
New Default
host_cache_size
128
Autosized using max_connections
innodb_log_file_size
5MB
48MB
open_files_limit
0
Autosized using max_connections
performance_schema
OFF
ON
performance_schema_events_waits_history_long_size
10000
Autosized
performance_schema_events_waits_history_size
10
Autosize
performance_schema_max_cond_instances
1000
Autosize
performance_schema_max_file_instances
10000
Autosize
performance_schema_max_mutex_instances
1000000
Autosize
performance_schema_max_rwlock_instances
1000000
Autosize
performance_schema_max_table_handles
100000
Autosize
performance_schema_max_table_instances
50000
Autosize
performance_schema_max_thread_instances
1000
Autosize
query_cache_size
0
1M
query_cache_type
ON
OFF
table_definition_cache
400
Autosized using table_open_cache
table_open_cache
400
2000
thread_cache_size
0
Autosized using max_connections
Installation Notes
• mysql_install_db is now a Perl script and can be used on any system with Perl installed. Previously,
it was a shell script and available only on Unix platforms.
150
MySQL 5.6 Release Notes
In addition, mysql_install_db is more strict about the --datadir option value. Only the last
component of the path name is created if it does not exist; the parent directory must already exist or an
error occurs. Previously, it created any nonexistent directories in the path name.
• On Unix platforms, mysql_install_db now creates a default option file named my.cnf in the base
installation directory. This file is created from a template included in the distribution package named mydefault.cnf. You can find the template in or under the base installation directory. When started using
mysqld_safe, the server uses my.cnf file by default. If my.cnf already exists, mysql_install_db
assumes it to be in use and writes a new file named my-new.cnf instead.
With one exception, the settings in the default option file are commented and have no effect.
The exception is that the file changes the sql_mode system variable from its default of
NO_ENGINE_SUBSTITUTION to also include STRICT_TRANS_TABLES:
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
This setting produces a server configuration that results in errors rather than warnings for bad data in
operations that modify transactional tables. See Server SQL Modes.
The my-default.cnf template replaces the older sample option files (my-small.cnf, mymedium.cnf, and so forth), which are no longer distributed.
• On Unix platforms, mysql_install_db supports a new option, --random-passwords, that provides
for more secure MySQL installation. Invoking mysql_install_db with --random-passwords causes
it to perform the following actions in addition to its normal operation:
• The installation process creates a random password, assigns it to the initial MySQL root accounts,
and sets the “password expired” flag for those accounts.
• The initial random root password is written to the .mysql_secret file in the directory named by the
HOME environment variable. Depending on operating system, using a command such as sudo may
cause the value of HOME to refer to the home directory of the root system user. .mysql_secret is
created with mode 600 to be accessible only to the system user for whom it is created.
If .mysql_secret already exists, the new password information is appended to it. Each password
entry includes a timestamp so that in the event of multiple install operations it is possible to determine
the password associated with each one.
• No anonymous-user MySQL accounts are created.
As a result of these actions, it is necessary after installation to start the server, connect as root using
the password written to the .mysql_secret file, and to select a new root password. Until this is done,
root cannot do anything else. This must be done for each root account you intend to use. To change
the password, you can use the SET PASSWORD statement (for example, with the mysql client). You can
also use mysqladmin or mysql_secure_installation.
New RPM install operations (not upgrades) invoke mysql_install_db with the --randompasswords option. As a consequence, RPM installs from this version onward will have their root
accounts secured, and will have no anonymous-user accounts. (Install operations using RPMs for
Unbreakable Linux Network are unaffected because they do not use mysql_install_db.)
For install operations using a binary .tar.gz distribution or a source distribution, you can invoke
mysql_install_db with the --random-passwords option manually to make your MySQL installation
more secure. This is recommended, particularly for sites with sensitive data.
151
MySQL 5.6 Release Notes
Security Notes
• On Windows, many MySQL executables depend on the libeay32.dll and ssleay32.dll SSL
libraries at runtime. To ensure that the proper versions of these libraries are found, the install process
copies them into the same directory as the executables.
Functionality Added or Changed
• InnoDB: The InnoDB transportable tablespace feature was enhanced to allow ALTER TABLE ...
IMPORT TABLESPACE to succeed in some cases where the corresponding .cfg file was not available.
This enhancement allows recovery of data even in some cases where the system tablespace is
corrupted or deleted. (Bug #14589582, Bug #66715)
• The number of atomic operations performed by the Performance Schema was reduced. (Bug
#14658739)
• ALTER USER now can be used as a prepared statement. (Bug #66874, Bug #14646014)
• On Unix systems, the mysql client writes statements executed interactively to a history file (see mysql
Logging). mysql now ignores for logging purposes statements that match any pattern in the “ignore”
list. By default, the pattern list is "*IDENTIFIED*:*PASSWORD*", to ignore statements that refer to
passwords. Pattern matching is not case sensitive. Within patterns, two characters are special:
• ? matches any single character.
• * matches any sequence of zero or more characters.
To specify additional patterns, use the --histignore command option or set the MYSQL_HISTIGNORE
environment variable. (If both are specified, the option value takes precedence.) The value should be a
colon-separated list of one or more patterns, which are appended to the default pattern list.
Patterns specified on the command line might need to be quoted or escaped to prevent your command
interpreter from treating them specially. For example, to suppress logging for UPDATE and DELETE
statements in addition to statements that refer to passwords, invoke mysql like this:
shell> mysql --histignore="*UPDATE*:*DELETE*"
(Bug #48287, Bug #11756377)
• The SHOW AUTHORS and SHOW CONTRIBUTORS statements have been removed.
Bugs Fixed
• Important Change; Replication: When running the slave with the --slave-skip-errors option,
successive skipped events (errors logged as warnings) were found to contain information from previous
warnings, which caused an excessive amount of redundant information to be written to the error log. This
problem could occur when using row-based or mixed-format binary logging.
The fix for this issue is to clear these warnings prior to processing the next skipped event. In addition,
the skipped events are now handled in the same way regardless of the value of binlog_format,
and a skipped error always causes a warning to be written to the error log, as long as the value of the
log_warnings system variable is greater than 1. (Bug #12776842)
• Important Change: The server system variables profiling, have_profiling, and
profiling_history_size are now deprecated, and are subject to removal in a future release of the
MySQL Server. (Bug #14658683)
152
MySQL 5.6 Release Notes
• InnoDB: The thread gathering persistent statistics for an InnoDB table could cause a serious error if it
accessed the table while a TRUNCATE TABLE operation was in progress:
InnoDB: Assertion failure in thread thread_num in file fsp0fsp.cc line 1882
(Bug #14765035)
• InnoDB: When a CREATE INDEX operation failed for an InnoDB FULLTEXT index due to a duplicate
key error, some allocated memory was not freed. (Bug #14759111)
• InnoDB: During a brief time window while creating an InnoDB unique index, MySQL could print a
spurious warning message:
WARNING: CANNOT FIND INDEX ?index_name IN INNODB INDEX TRANSLATION TABLE
The cause was that MySQL started enforcing the uniqueness constraint before the existence of the
index was fully registered. The fix suppresses the incorrect message during this final stage of index
creation. (Bug #14735988)
• InnoDB: An online DDL operation to create a unique index could fail to detect duplicate index values,
when the duplicate values were caused by DML operations while the index was being created. (Bug
#14733674)
• InnoDB: During an online DDL operation, a duplicate key error could be incorrectly issued if a record
was inserted and subsequently updated while the table was being rebuilt. (Bug #14723456)
• InnoDB: The auxiliary tables for FULLTEXT indexes were being created in the system tablespace,
regardless of the setting for the innodb_file_per_table configuration option. (Bug #14723291)
• InnoDB: When using the transportable tablespace feature, the ALTER TABLE ... IMPORT
TABLESPACE statement could crash if the InnoDB table being flushed contained a FULLTEXT index.
With this fix, the table data can be imported, although you must drop and re-create the FULLTEXT index
after the import operation. (Bug #14712962, Bug #67081)
• InnoDB: An assertion failure occurred when a bogus duplicate key error was flagged during online
ALTER TABLE. This issue only occurred for a table that lacked a primary key and any secondary
indexes. This patch fixes the assertion failure, but not the bogus duplicate key error, which is reported as
Bug#14723456. (Bug #14712710)
• InnoDB: The InnoDB memcached plugin can now work with tables where the underlying character set
is multibyte. (Bug #14711015, Bug #67076)
• InnoDB: If a CREATE TABLE statement failed due to a disk full error, some memory allocated during the
operation was not freed properly. (Bug #14708715)
• InnoDB: An ALTER TABLE operation on an InnoDB table containing a FULLTEXT index could cause
make the server halt with an assertion error. The fix causes all ALTER TABLE operations for such tables
to use the table-copying behavior of the ALGORITHM=COPY clause. (Bug #14681198)
• InnoDB: If the server crashed while executing TRUNCATE TABLE for an InnoDB table containing a
FULLTEXT index, further errors could occur during crash recovery, preventing the server from restarting.
(Bug #14676345)
• InnoDB: If an InnoDB table containing a FULLTEXT index was being modified by a TRUNCATE TABLE
statement and on online DDL operation simultaneously, the server could end up with inconsistent
internal locks or could crash. (Bug #14676329)
153
MySQL 5.6 Release Notes
• InnoDB: If creation of a FULLTEXT index failed because of a “row too large” condition, a subsequent
ALTER TABLE operation could cause the server to halt with an error. (Bug #14668777)
• InnoDB: If the MySQL server crashed while XA transactions were in PREPARED state, inconsistent
data could be produced during crash recovery if the query cache was enabled. The fix allows MySQL to
disable the query cache during crash recovery if required. (Bug #14658648)
• InnoDB: MySQL could crash while creating an InnoDB table if the disk became full at a specific
moment: after the .frm file was created but before the corresponding .ibd file was created. (Bug
#14645935)
• InnoDB: If the server crashed at the specific point when a change buffer entry was being merged into
a buffer pool page, the transaction log and the change buffer were left in an inconsistent state. After
a restart, MySQL could crash after reading the corresponding secondary index page. The problem
was more likely to occur in MySQL 5.5 or later, where the original insert buffering mechanism was
generalized to cover other operations. (Bug #14636528, Bug #66819, Bug #58571, Bug #61104, Bug
#65443)
• InnoDB: If a crash occurred during a CREATE TABLE operation, the InnoDB data dictionary could
be left in an inconsistent state, causing a crash if the partially created table was accessed later. (Bug
#14601290)
• InnoDB: On startup, MySQL would not start if there was a mismatch between the value of the
innodb_log_file_size configuration option and the actual size of the ib_logfile* files that make
up the redo log. This behavior required manually removing the redo log files after changing the value of
innodb_log_file_size. The fix causes MySQL to write all dirty pages to disk and re-create the redo
log files during startup if it detects a size mismatch. (Bug #14596550)
• InnoDB: With the innodb_file_per_table setting enabled, a DROP TABLE operation could cause
a crash, due to a race condition that depended on the timing of pending I/O requests. (Bug #14594600,
Bug #66718)
• InnoDB: If an online DDL operation failed due to a duplicate key error, caused by DML changes being
made concurrently to the table, the server could crash with an assertion error. (Bug #14591797)
• InnoDB: A query against an InnoDB table with a FULLTEXT index could crash, if the AGAINST clause
contained a character sequence that was encoded incorrectly for the character set of the table. (Bug
#14588091)
• InnoDB: If a FULLTEXT index was dropped from an InnoDB table, and the server crashed later for an
unrelated reason, an additional error could occur while attempting to access nonexistent FULLTEXT data
structures. (Bug #14586855)
• InnoDB: The server could crash with a confusing message if it ran out of space for temporary files
during index creation.
InnoDB: Assertion failure in thread thread_num in file mtr0mtr.cc line 306
InnoDB: Failing assertion: mtr->state == 12231
(Bug #14586256)
• InnoDB: An ALTER TABLE on an InnoDB table that dropped the primary key and then re-created it
with columns in a different order could cause an error. The issue affected tables where the swapped
columns referenced each other in a single-table foreign key relationship. The data dictionary could be left
in an inconsistent state, where the table was listed in SHOW TABLES output but could not be queried or
dropped. For example, if the table was declared with primary key columns (c1,c2) and a foreign key
with c1 REFERENCES c2:
154
MySQL 5.6 Release Notes
ALTER TABLE t2 DROP PRIMARY KEY, ADD PRIMARY KEY (c2, c1);
ERROR 1030 (HY000): Got error 38 from storage engine
(Bug #14548753)
• InnoDB: During an online DDL operation, a ROLLBACK affecting the same table could cause an
assertion error if the table formerly contained a FULLTEXT index. Some bookkeeping information
related to FULLTEXT indexes for InnoDB tables is preserved even after such an index is dropped. (Bug
#14503700)
• InnoDB: If a table was defined with an index key length very close to the upper length limit of 3072, a
query against that table could cause a serious error. (Bug #14500557, Bug #14537695)
• InnoDB: Table names containing non-ASCII characters were displayed incorrectly when the
MYSQL.INNODB_TABLE_STATS.TABLE_NAME column was queried. (Bug #14404879)
• InnoDB: A race condition could cause a crash during an online CREATE INDEX statement for an
InnoDB table. This bug only affected very small tables. It required a DML operation to be in progress
for the table, affecting the primary key columns, at the same time the CREATE INDEX statement was
issued. (Bug #14117641)
• InnoDB: If a transaction was started with a consistent snapshot, then new indexes were added to the
table while the transaction was in progress, a subsequent UPDATE statement could incorrectly encounter
the error:
ER_TABLE_DEF_CHANGED: insufficient history for index
This issue could cause an assertion error in debug builds. (Bug #14036214)
• InnoDB: The server could crash with an assertion error during operations on tables with
ROW_FORMAT=COMPRESSED. (Bug #14001972)
• InnoDB: In rare circumstances, during operations on an InnoDB table containing foreign keys, pages in
the buffer pool could be evicted but not written to disk, leading to data inconsistency. (Bug #13688491)
• InnoDB: In rare circumstances, MySQL could apply InnoDB undo records out of order during a
ROLLBACK of an operation that modified a BLOB column. This issue could cause an assertion error in
debug builds:
!bpage->file_page_was_freed
(Bug #13249921)
• InnoDB: In debug builds, a mismatch in the InnoDB PAGE_FREE list would cause an assertion. (Bug
#12701488)
• Partitioning: The server now skips pruning of tables (see Partition Pruning) that use a storage engine
which handles its own partitioning internally. The server now also explicitly rejects attempts to use
explicit partitioning for such tables. (Bug #14672885)
• Partitioning: When used with a table having multiple columns in its primary key, but partitioned by
KEY using a column that was not part of the primary key as the partitioning column, a query using an
aggregate function and DISTINCT such as SELECT SUM(DISTINCT pk_column_1) FROM table
WHERE pk_column_2 = constant was not handled correctly. (Bug #14495351)
155
MySQL 5.6 Release Notes
• Replication: When using a multi-threaded slave, if all worker threads were kept busy, it was possible
for cleanup of an internal MTS circular buffer to fail, resulting in a full buffer and failure of the slave. (Bug
#14710881)
• Replication: Executing FLUSH LOGS in parallel with COMMIT could cause the server to hang. (Bug
#14640486)
• Replication: When invoked while gtid_mode was set to OFF, the
SQL_THREAD_WAIT_AFTER_GTIDS() function waited indefinitely, unless a timeout was specified.
In the latter case, the function could return incorrect values. Now, when gtid_mode is OFF,
SQL_THREAD_WAIT_AFTER_GTIDS() always returns NULL, as expected. (Bug #14640065)
• Replication: Partially-failed GRANT and REVOKE statements were not always handled the same way on
the master and the slave. We now log an incident event whenever an error occurs, even if it is only a
partial error, with a message stating that manual reconciliation is required. (Bug #14598585)
• Replication: There existed a gap in time between the appending of the current GTID to the server's list
of logged GTIDs and the commit of the transaction by the storage engine. On slow platforms, or when
using profiling, this could cause SELECT SQL_THREAD_WAIT_AFTER_GTIDS(gtid) to return before
the data actually reached the database.
Now the current GTID is appended to the logged GTIDs following the commit, which removes this gap
and so eliminates a possible source of inconsistency. (Bug #14116526)
• Replication: The error shown when a relay log file was missing from the relay log index file informed
the user only that the log file was not found, but did not specify the exact reason. Now in such cases,
the error message returned is Could not find target log file mentioned in relay log
info in the index file 'index_file_name' during relay log initialization. (Bug
#11758505)
• Replication: Following an insert into a nontransactional table that failed due to insufficient disk space,
the server did not properly clean up all pending events, leading to an assert or possibly to other errors.
(Bug #11750014)
• Replication: Backtick (`) characters were not always handled correctly in internally generated SQL
statements, which could sometimes lead to errors on replication slaves or cause failure of restore
operations from binary log files. (Bug #66550, Bug #14548159, Bug #29422, Bug #11746883)
• A DELETE statement for an InnoDB table could write incorrect transaction metadata into a record,
causing the server to halt with an error. To work around this issue, reduce the specified length of the
primary key to less than 1K bytes. (Bug #14731482)
• mysql_secure_installation could not change the password for an account that had
password_expired='Y' in the mysql.user table row for that account. (Bug #14726722)
• For an in-place ALTER TABLE operation on an InnoDB table that produced a duplicate-key error for
NULL values, the error message displayed the column default value rather than NULL. (Bug #14723364)
• Patches for materialized semi-joins caused failures of the query plan interface used by NDBCLUSTER.
(Bug #14704659)
• mysqladmin password did not work for accounts with an expired password. (The fix for this problem
is limited to accounts with passwords that use native or “old” native hashing. It still does not handle
accounts that use SHA-256 password hashing.)
As a consequence of this patch, the restricted mode of operation enforced by the server on operations
permitted to clients with expired passwords now includes SET statements in addition to SET PASSWORD.
156
MySQL 5.6 Release Notes
This is useful if the account uses a password hashing format that requires old_passwords to be set to
a value different from its default. (Bug #14698309)
• Repeated execution of a query containing a subquery that used MAX() could result in increasing
memory consumption. (Bug #14683676)
• Queries that used a nested join with a subquery in the FROM clause and an ORDER BY ... DESC
clause could return too few rows. (Bug #14678404)
• With the optimizer tracing enabled, the INFORMATION_SCHEMA.OPTIMIZER_TRACE table can be
queried to find tracing information about the last statements. However, for queries for which the results
were retrieved from the query cache, this information was not available. (Bug #14665052)
• There was a performance regression for queries using SELECT ... INTO user variables and a WHERE
condition on one or more of the variables in the INTO list. (Bug #14664077)
References: This issue is a regression of: Bug #12408412.
• In debug builds, the server could crash because db_suicide() failed to handle SIGABRT signals. (Bug
#14649493)
• USE dbname could fail with Unknown database when dbname contained multiple backtick (`)
characters. (Bug #14645196)
• Outer joins could execute inefficiently and return incorrect results if joins were pushed down to the
storage engine. (Bug #14644936)
• A prepared statement that referenced views in an IN subquery could return different results for different
executions. (Bug #14641759)
References: See also: Bug #13773979.
• Within a stored program, memory allocated to hold condition information was not released until program
exit, leading to excessive memory use. (Bug #14640599)
• Attempts to insert, update, delete from, or lock unknown Performance Schema tables failed with an
ER_TABLEACCESS_DENIED_ERROR error rather than ER_NO_SUCH_TABLE. (Bug #14633008)
• An incomplete result could be stored in the query cache when a query failed with an error (providing
that the query cache was enabled, and was set to a nonzero size). This fix ensures that it is no longer
possible for queries that finish with an error to be cached. (Bug #14621700)
References: This issue is a regression of: Bug #40264.
• The thread cache implementation worked in LIFO rather than FIFO fashion and could result in a thread
being denied service (although this was a remote possibility). (Bug #14621627)
• The server could crash when registering tables in the query cache for queries that selected from views.
(Bug #14619935)
• With semi-join and materialization optimizations enabled, a query that materialized a const table
returned incorrect results when STRAIGHT_JOIN was added. (Bug #14609394)
• Index condition pushdown in conjunction with descending index range scan could return incorrect results
if there were multiple ranges in the range scan. (Bug #14604223)
• EXPLAIN DELETE ... WHERE impossible_condition could function incorrectly when it was used
in a stored routine. (Bug #14601802)
157
MySQL 5.6 Release Notes
References: This issue is a regression of: Bug #11752097.
• Small values of max_sort_length could produce incorrect results for integer, decimal, floating-point,
or temporal data types. Now max_sort_length is ignored for those data types. (Bug #14596888)
• The configure.pl script that converts GNU configure options to CMake equivalents generated
erroneous output for the --with-client-ldflags and --with-mysqld-ldflags options. It now
ignores those options. (Bug #14593123)
• A query with a subquery and ORDER BY and LIMIT clauses returned fewer rows than expected when
executed using semi-join materialization. (Bug #14580874)
• The server printed excessive Got error 159 when reading table messages to the error log
when one transaction attempted to access a table that had been modified by another. (Bug #14579877)
• The optimizer could choose an incorrect execution plan for updates to InnoDB tables based on indexes
that use column prefixes. (Bug #14578060)
• Materialization of a subquery in the FROM clause could return the wrong number of rows if the subquery
included a LIMIT clause. (Bug #14576727)
• In-source builds modified the source file sql/share/dictionary.txt. (Bug #14562699)
• Improper memory cleanup could cause the server to exit. (Bug #14536113)
• A query with a subquery in the JOIN ... ON clause with an outer reference to a field that was out of
scope could cause the server to crash. (Bug #14498914)
• On Windows, mysql_plugin could not find my_print_defaults. (Bug #14471052)
• When used in GRANT statements, quoted user name or host name values containing leading or trailing
spaces caused privileges to be assigned incorrectly until a FLUSH PRIVILEGES statement was issued.
Now, as a result of this fix, quoted name and host identifiers used in a GRANT statement are
automatically trimmed of any leading and trailing spaces, before privileges are assigned. (Bug
#14328259)
• Granting or revoking the PROXY privilege caused the server to exit if the server was started with -skip-name-resolve. (Bug #14211140)
• CREATE USER and DROP USER could fail to flush the privileges, requiring FLUSH PRIVILEGES to be
used explicitly. (Bug #13864642)
• On OS X, the version_compile_machine system variable did not include the value 64 for server
binaries compiled on a 64-bit system. (Bug #13859866)
• Access to INFORMATION_SCHEMA tables through a view could leak memory. (Bug #13734987)
• On Microsoft Windows with CMake 2.6, the build process would not stop if the create_initial_db
step failed. (Bug #13713525)
• The test in mysqld_safe for the presence of the --plugin_dir option and assignment of a default
value to it were performed before the actual argument parsing took place. (Bug #13548161)
• A cached query result was not empty at the end of statement execution as expected. This could occur
when executing queries (with the query cache enabled and set to a nonzero size) where the result was
not sent to the client such as those executed by the Event Scheduler, or when executing stored routines
containing queries while the server was running in bootstrap mode. (Bug #11755580, Bug #14609893)
158
MySQL 5.6 Release Notes
• The number of connection errors from a given host as counted by the server was periodically reset, with
the result that max_connect_errors was never reached and invalid hosts were never blocked from
trying to connect. (Bug #11753779)
References: See also: Bug #38247, Bug #43006, Bug #45584, Bug #45606.
• The Range checked for each record optimization is now used for conditions with outer query
references. (Bug #11750963)
• Random number generation during client authentication consumed excessive CPU. (Bug #66567, Bug
#14555434)
• Metadata locking resulted in excessive contention in read-only workloads involving InnoDB tables and a
low number of connections.
Now the set of metadata locks can be partitioned into separate hashes to permit connections
accessing different objects to use different locking hashes and reduce contention. The new
metadata_locks_hash_instances system variable can be used to specify the number of hashes.
(Bug #66473, Bug #14569140)
• On Windows, the Perl version of mysql_install_db created system tables in the mysql database
that were not populated properly. (Bug #65584, Bug #14181049)
• ST_Contains() and ST_Within() incorrectly reported that a polygon did not contain itself.
ST_Equals() incorrectly returned 0 for polygons that differed only in shifted vertices. (Bug #64653, Bug
#13864679)
• ST_Difference() could incorrectly produce empty polygons in the result. (Bug #64649, Bug
#13865773)
• libmysqlclient did not use symbol versioning. Thanks to Nicholas Bamber for the patch. (Bug
#64386, Bug #13788218)
• The parser rejected legal queries that involved a UNION where the right hand side query term has a table
in parenthese. (Bug #54382, Bug #11761854)
• For some queries involving ORDER BY, the optimizer chose the wrong index for accessing the table.
(Bug #45969, Bug #11754370, Bug #14338686)
• In debug builds, vio_read() printed errno rather than socket_error to the debug trace. (Bug
#28775, Bug #11746795)
Changes in MySQL 5.6.7 (2012-09-29, Release Candidate)
Beginning with MySQL 5.6.7, Oracle no longer provides binaries for OS X 10.5, Debian 5, RHEL/OL 4,
SLES 10, FreeBSD 7, Windows XP, or Windows 2003.
• Configuration Notes
• Functionality Added or Changed
• Bugs Fixed
Configuration Notes
• This release continues the process begun in MySQL 5.6.6 of making changes to the default values of
server parameters. The motivation for these changes is to provide better out-of-box performance and to
159
MySQL 5.6 Release Notes
reduce the need for database administrators to change settings manually. These changes are subject to
revision in future releases as we gain feedback.
The following table summarizes changes to defaults. Any of these default settings can be overridden by
specifying an explicit value at server startup.
Parameter
Old Default
New Default
innodb_data_file_path
ibdata1:10M:autoextend
ibdata1:12M:autoextend
Functionality Added or Changed
• Important Change; Partitioning: The maximum number of partitions for a user-partitioned table is
increased from 1024 to 8192. (Bug #11755685)
• Important Change: In MySQL 5.6.6, INSERT DELAYED was deprecated, to be removed in a future
release. The same is now also true for DELAYED-related system variables delayed_insert_limit,
delayed_insert_timeout, delayed_queue_size, max_delayed_threads, and
max_insert_delayed_threads, and DELAYED-related status variables Delayed_errors,
Delayed_insert_threads, Delayed_writes, and Not_flushed_delayed_rows.
• Performance; InnoDB: A new setting O_DIRECT_NO_FSYNC was added to the
innodb_flush_method configuration option. This setting is similar to O_DIRECT, but omits the
subsequent fsync() call. Suitable for some filesystems but not others. (Bug #11754304, Bug #45892)
• InnoDB: The --innodb-read-only option lets you run a MySQL server in read-only mode. You
can access InnoDB tables on read-only media such as a DVD or CD, or set up a data warehouse with
multiple instances all sharing the same data directory. See Configuring InnoDB for Read-Only Operation
for usage details. (Bug #14143600)
• InnoDB: New INFORMATION_SCHEMA tables, innodb_cmp_per_index and
innodb_cmp_per_index_reset, provide statistics on InnoDB tables that use compression. The
statistics at the index level let DBAs measure whether the proportion of successful or failed compression
operations is acceptable for a particular combination of table, index, page size, and workload. Typically,
the compression failure rate should be less than 10%, particularly when using a compressed table to
handle an OLTP-style workload with frequent INSERT, UPDATE, or DELETE operations.
Because gathering those statistics could be very time consuming and would hurt
performance negatively, the new tables are enabled only when the new configuration option
innodb_cmp_per_index_enabled is set to ON. (It is OFF by default.)
• InnoDB: Each data block in an InnoDB compressed table contains a certain amount of empty space
(padding) to allow DML operations to modify the row data without re-compressing the new values.
Too much padding can increase the chance of a compression failure, requiring a page split, when the
data does need to be re-compressed after extensive changes. The amount of padding can now be
adjusted dynamically, so that DBAs can reduce the rate of compression failures without re-creating
the entire table with new parameters, or re-creating the entire instance with a different page size.
The associated new configuration options are innodb_compression_failure_threshold_pct,
innodb_compression_pad_pct_max
• InnoDB: You can now select the compression level for InnoDB compressed tables, from the familiar
range of 0-9 used by zlib. The compression level is controlled by the innodb_compression_level
configuration option, with a default value of 6:
• Increasing the compression level increases CPU overhead, possibly reducing the amount of storage
needed for any particular row, reducing the possibility of a compression failure and subsequent page
split.
160
MySQL 5.6 Release Notes
• Decreasing the compression level reduces CPU overhead, possibly increasing the amount of storage
needed for any particular row, increasing the possibility of a compression failure and subsequent page
split.
You can also control whether compressed pages in the buffer pool are stored in the redo log when
an update operation causes pages to be compressed again. This behavior is controlled by the
innodb_log_compressed_pages configuration option. Turning off logging for compressed pages
reduces the amount of redo data that is generated, possibly improving throughput. If the compressed
page is required during crash recovery, it is compressed again at that time.
• When MySQL is configured with -DWITH_SSL=system to build with OpenSSL, CMake now produces
an error if OpenSSL is older than version 1.0.1 (Bug #14167227)
• The default has changed from false to true for the --secure-auth option for mysql and the
MYSQL_SECURE_AUTH option for the mysql_options() C API function. (Bug #13789417)
• The WITH_SSL option for CMake now accepts a path_name value that indicates the path name to the
OpenSSL installation to use. This can be useful instead of a value of system when the CMake code
detects an older or incorrect installed OpenSSL version. (Another permitted way to do the same thing is
to set the CMAKE_PREFIX_PATH option to path_name.) (Bug #61619, Bug #12762891)
• The server now issues a Note diagnostic if an index is created that duplicates an existing index. (Bug
#37520, Bug #11748842)
• The following items are deprecated and will be removed in a future MySQL release. Where alternatives
are shown, applications should be updated to use them.
• The SHOW PROFILE and SHOW PROFILES statements. Use the Performance Schema instead; see
MySQL Performance Schema.
• The unused date_format datetime_format time_format, and max_tmp_tables system
variables.
• The obsolete mysql.host table. New MySQL 5.6 installations will no longer create this table. For
upgrades, mysql_upgrade will check for this table and issue a warning about it being deprecated if it
is nonempty.
• The (undocumented) --plugin-xxx syntax for controlling plugin option xxx.
• The unused multi_range_count system variable is now deprecated, and will be removed in a future
release.
• The MySQL client library now includes SSL support built in. When linking MySQL client programs, you
should no longer specify either -lssl or -lcrypto.
References: See also: Bug #12762891, Bug #14167227.
• The mysql_clear_password cleartext client-side authentication plugin is intended for authentication
schemes that require the server to receive the password as entered on the client side, without hashing.
Because the password is sent in the clear, this plugin should be used within the context of an encrypted
connection, such as an SSL connection, to avoid exposing the password over the network. To make
inadvertent use of this plugin less likely, it is now required that clients explicitly enable it. This can be
done several ways:
• Set the LIBMYSQL_ENABLE_CLEARTEXT_PLUGIN environment variable to a value that begins with 1,
Y, or y. This enables the plugin for all client connections.
161
MySQL 5.6 Release Notes
• The mysql, mysqladmin, and mysqlslap client programs support an --enable-cleartextplugin option that enables the plugin on a per-invocation basis.
• The mysql_options() C API function supports a MYSQL_ENABLE_CLEARTEXT_PLUGIN option that
enables the plugin on a per-connection basis. Also, any program that uses libmysqlclient and
reads option files can enable the plugin by including an enable-cleartext-plugin option in an
option group read by the client library.
Bugs Fixed
• Incompatible Change: Using ALTER TABLE to change the definition of a foreign key column could
cause a loss of referential integrity. For example, changing a foreign key column that contained NULL
values to be NOT NULL caused the NULL values to be the empty string. Similarly, an ALTER TABLE
IGNORE that removed rows in a parent table could break referential integrity.
The server now prohibits changes to foreign key columns with the potential to cause loss of referential
integrity. A workaround is to use ALTER TABLE ... DROP FOREIGN KEY before changing the column
definition and ALTER TABLE ... ADD FOREIGN KEY afterward. (Bug #46599, Bug #11754911)
• Important Change; Replication: When issued during an ongoing transaction, any of the following
statements that are used to control MySQL Replication now cause the transaction to be committed:
• CHANGE MASTER TO
• START SLAVE
• STOP SLAVE
• RESET SLAVE
For more information, see Statements That Cause an Implicit Commit. (Bug #13858841)
References: See also: Bug #14298750, Bug #13627921.
• Important Change: The ALTER USER statement cleared the user password in the mysql.user table.
It no longer does this. (Bug #14226518)
• Important Change: Formerly, the ExtractValue() and UpdateXML() functions supported a
maximum length of 127 characters for XPath expressions supplied to them as arguments. This limitation
has now been removed. (Bug #13007062, Bug #62429)
• Performance; InnoDB: This fix improves the performance of the InnoDB memcached plugin in several
ways:
• A background thread periodically commits changes made to the database through memcached
API calls. This commit interval based on time rather than number of operations lets you increase
the value of daemon_memcached_w_batch_size and daemon_memcached_r_batch_size
without the risk of some changes remaining uncommitted when DML activity is infrequent. You can
control the frequency of these automatic commits through the innodb_api_bk_commit_interval
configuration option.
• When binary log support is enabled through the innodb_api_enable_binlog configuration option,
you can increase the value of daemon_memcached_w_batch_size higher than the default of 1,
allowing several DML operations to be committed together rather than a separate commit for each
one.
162
MySQL 5.6 Release Notes
• Internally, the efficiency of mutexes and table opening/closing was improved for operations involving
the memcached plugin.
(Bug #14252821)
• Performance; InnoDB: The OPTIMIZE TABLE statement now updates the InnoDB persistent statistics
for that table when appropriate. (Bug #14238097)
• Performance; InnoDB: This fix removes redundant checksum validation on InnoDB pages. The
checksum was being verified both when a compressed page was read from disk and when it was
uncompressed. Now the verification is only performed when the page is read from disk. (Bug
#14212892, Bug #64170)
• Performance; Replication; Solaris: On Solaris systems, enabling slave_parallel_workers could
lead to a slowdown in event executions on the slave. (Bug #14641110)
References: See also: Bug #13897025.
• Performance; Replication: When slave_parallel_workers was enabled, an internal multiplier
representing the number of events above a certain overrun level in the worker queue was never reset
to zero, even when the excess had been taken care of; this caused the multiplier to grow without
interruption over time, leading to a slowdown in event executions on the slave. (Bug #13897025)
• Performance: View definitions (in .frm files) were not cached and thus every access to a view involved
a file read. Definitions now are cached for better performance. (Bug #13819275)
• Performance: Certain instances of subquery materialization could lead to poor performance. Subquery
materialization now is chosen only if it is less costly than the EXISTS transformation. (See Optimizing
Subqueries with Materialization, and Optimizing Subqueries with the EXISTS Strategy.)
This fix introduces a new flag for the optimizer_switch system variable named
subquery_materialization_cost_based. If the flag is on (the default), the optimizer performs a
cost-based choice between subquery materialization and IN -> EXISTS subquery transformation if
either method could be used. If the flag is off, the optimizer chooses subquery materialization over IN
-> EXISTS subquery transformation, which was the previous behavior. (Bug #13111584)
• InnoDB; Partitioning: A SELECT from a partitioned InnoDB table having no primary key sometimes
failed to return any rows where a nonempty result was expected. In such cases the server also
returned the error Can't find record in table_name or Incorrect key file for table
table_name. (Bug #13947868)
• InnoDB: When configuring the InnoDB memached plugin system table,
INNODB_MEMCACHE.CONTAINERS, a comma (“,”) and empty space are used as a delimiter for mapping
multiple columns to a memcached value. This fix allows the pipe character, (“|”), to also be used as a
delimiter. (Bug #14560228)
• InnoDB: On Windows systems, a file access error due to an incorrect value for MYSQL_DATADIR could
cause an InnoDB assertion error. The error could persist after restarting MySQL. (Bug #14558324)
• InnoDB: Inserting data of varying record lengths into an InnoDB table that used compression could
cause the server to halt with an error. (Bug #14554000, Bug #13523839, Bug #63815, Bug #12845774,
Bug #61456, Bug #12595091, Bug #61208)
• InnoDB: The default for the innodb_checksum_algorithm, which was briefly changed to crc32
during the MySQL 5.6 development cycle, was switched back to innodb for improved compatibility of
InnoDB data files during a downgrade to an earlier MySQL version. (Bug #14525151)
163
MySQL 5.6 Release Notes
• InnoDB: In an ALTER TABLE that rebuilds a table, and in particular, ADD COLUMN, DROP COLUMN,
there were some assertion failures related to FULLTEXT indexes, particularly for tables containing
more than one FULLTEXT index. The fix makes the ALTER TABLE correctly use or not use online DDL
depending on the presence of FULLTEXT indexes. If a table had a FULLTEXT index that was dropped,
any restrictions on online DDL for that table remain, due to the hidden FTS_DOC_ID column. (Bug
#14488218)
• InnoDB: Under certain conditions, the innodb_io_capacity_max configuration option now uses the
following formula to calculate a default value:
innodb_io_capacity_max = max(2000, innodb_io_capacity * 2)
The formula only takes affect when you specify a value for innodb_io_capacity at server startup and
do not specify a value for innodb_io_capacity_max. The formula is not used when setting a value
for innodb_io_capacity dynamically using a SET statement. (Bug #14469086)
• InnoDB: Under heavy load of concurrent DML and queries, an InnoDB table with a unique index could
return nonexistent duplicate rows to a query. (Bug #14399148, Bug #66134)
• InnoDB: The syntax ALTER TABLE ... DROP FOREIGN KEY ... ALGORITHM=COPY incorrectly
considered the names of foreign keys to be case-sensitive. (Bug #14394071)
• InnoDB: When an error (such as a duplicate key error) was detected during an online DDL operation,
while applying changes made to the table while an index was being built, MySQL could encounter an
assertion error if the same ALTER TABLE statement also contained any DROP INDEX clauses. (Bug
#14392805)
• InnoDB: When an InnoDB table had a system-chosen primary key, based on a unique index on nonnullable columns, an error was issued if one of the primary key columns was altered to be nullable. The
message was:
Warning 1082 InnoDB: Table table_name has a primary key in InnoDB data
dictionary, but not in MySQL!
This issue only affected ALTER TABLE statements using the online DDL mechanism, that is, with the
ALGORITHM=INPLACE clause specified or implied. (Bug #14353985)
• InnoDB: A heavy query workload against an InnoDB table with a FULLTEXT index could cause a crash.
The issue only occurred with some number of queries per second and some number of concurrent
connections. (Bug #14347352)
• InnoDB: If an online CREATE INDEX operation failed, there was a brief period of time when concurrent
DML operations could fail because the table was considered to be in an error state. (Bug #14341099)
• InnoDB: ALTER TABLE statements for partitioned tables could cause unnecessary locking and undo
information. As part of the new online DDL feature, MySQL minimizes this overhead when practical, or
you can specify the ALGORITHM=INPLACE clause on the ALTER TABLE statement. (Bug #14322667)
• InnoDB: The mysql_install_db command could crash with an assertion error:
InnoDB: Assertion failure in thread thread_num in file trx0rseg.cc line 326
The size of the InnoDB system tablespace was being capped at 10MB, but during the 5.6 development
cycle, the minimum size of a system tablespace became slightly larger than 10MB. (Bug #14315223)
164
MySQL 5.6 Release Notes
• InnoDB: A race condition could cause assertion errors during a DROP TABLE statement for an InnoDB
table. Some internal InnoDB functions did not correctly determine if a tablespace was missing; other
functions did not handle the error code correctly if a tablespace was missing. (Bug #14251529)
• InnoDB: When more than one InnoDB temporary table was created and accessed within the same
transaction, queries on those temporary tables could fail with an ER_TABLE_DEF_CHANGED error. (Bug
#14234581)
• InnoDB: The server could crash with a combination of a transaction with SERIALIZABLE isolation level,
FLUSH TABLES ... WITH READ LOCK, and a subsequent query. The error message was:
InnoDB: Failing assertion: prebuilt->stored_select_lock_type != LOCK_NONE_UNSET
(Bug #14222066)
• InnoDB: This fix addresses several issues regarding AUTO_INCREMENT columns when adding a column
using online DDL (that is, with ALGORITHM=INPLACE). Now the AUTO_INCREMENT_OFFSET value is
used properly, the calculation for the next value is corrected, FLOAT, DOUBLE, and unsigned INTEGER
auto-increment values are handled correctly, and overflow conditions are detected. (Bug #14219624)
• InnoDB: With the MySQL 5.6 online DDL feature, an ALTER TABLE statement to add a primary key to
an InnoDB table could succeed, even though the primary key columns contained duplicate values. (Bug
#14219515)
• InnoDB: This fix prevents online DDL operations from conflicting with foreign key operations happening
simultaneously on the same table. Updates or deletes based on CASCADE or SET NULL clauses in the
foreign key definition are blocked while the online DDL is in progress, because the information needed
in case of a ROLLBACK would not be available after the ALTER TABLE statement completes. (Bug
#14219233)
• InnoDB: A SHOW ENGINE...STATUS command could crash if an XA transaction was created using the
statement START TRANSACTION READ ONLY. (Bug #14218867)
• InnoDB: The server could crash if a read-only transaction was killed in a session that contained an
InnoDB temporary table. (Bug #14213784)
• InnoDB: An INSERT into a table after a failed online DDL operation could cause an erroneous assertion
error:
InnoDB: Failing assertion: prebuilt->trx_id == 0 || prebuilt->trx_id <= last_index->trx_id
(Bug #14176821)
• InnoDB: The server could hang at startup, during crash recovery, if the rollback of previously active
transactions conflicted with the dropping of temporary tables. With this fix, persistent statistics do not
apply to InnoDB temporary tables. (Bug #14175080)
• InnoDB: The configuration option innodb_max_io_capacity was renamed to
innodb_io_capacity_max, to emphasize its relationship to the existing innodb_io_capacity
option. (Bug #14175020)
• InnoDB: An online DDL operations to add a foreign key could incorrectly leave some memory allocated
if the DDL encountered an error. (Bug #14156259)
• InnoDB: The server could crash with a signal 8 (division by zero error) due to a race condition while
computing index statistics. (Bug #14150372)
165
MySQL 5.6 Release Notes
• InnoDB: When an auto-increment column used a FLOAT or DOUBLE data type, if the auto-increment
value became very large (larger than the maximum unsigned long long value), subsequent inserts
could fail or cause the server to halt. (Bug #14145950, Bug #55071)
• InnoDB: Deleting from an InnoDB table containing a prefix index, and subsequently dropping the index,
could cause a crash with an assertion error. (Bug #13807811)
• InnoDB: The value of the NUMBER_PAGES_CREATED and NUMBER_PAGES_WRITTEN columns of the
INFORMATION_SCHEMA.INNODB_BUFFER_POOL_STATS table were set to incorrect values, and the
NUMBER_PAGES_GET column was not being set at all. (Bug #13639187)
• InnoDB: The error message was improved for the case where an UPDATE failed because the row
included several BLOB values greater than 768 bytes each, causing the size of a row to exceed half the
page size. The old message, was misleading; it suggested using BLOBs, when the 768-byte prefix for
each BLOB column was the cause of the limit error:
Error Code 1118: Row size too large. The maximum row size for the used table
type, not counting BLOBs, is 8126. You have to change some columns to TEXT or
BLOBs
A workaround for the problem was to create the table with the ROW_FORMAT=DYNAMIC or
ROW_FORMAT=COMPRESSED clause, which is now suggested in the message. (Bug #13453036, Bug
#63507)
• InnoDB: The server could crash when updating very large BLOB values, typically 16MB or more. (Bug
#13450566)
• InnoDB: A problem in the locking mechanism could cause a serious error with queries using the
HANDLER statement. (Bug #11766271, Bug #59344)
• InnoDB: When a SELECT ... FOR UPDATE, UPDATE, or other SQL statement scanned rows in an
InnoDB table using a < or <= operator in a WHERE clause, the next row after the affected range could
also be locked. This issue could cause a lock wait timeout for a row that was not expected to be locked.
The issue occurred under various isolation levels, such as READ COMMITTED and REPEATABLE READ.
(Bug #11765218)
• InnoDB: The new online DDL feature addressed long-standing bugs where ALTER TABLE statements
caused table rebuilds unnecessarily. This particular bug applied to changing default values for
TIMESTAMP columns. (Bug #11753646, Bug #45124)
• InnoDB: Various inconsistent behaviors, including tables becoming inaccessible, were cleaned up
for ALTER TABLE statements involving InnoDB tables involved in foreign key relationships. (Bug
#11744929, Bug #5670)
• Partitioning: For tables using PARTITION BY HASH or PARTITION BY KEY, when the partition
pruning mechanism encountered a multi-range list or inequality using a column from the partitioning
key, it continued with the next partitioning column and tried to use it for pruning, even if the previous
column could not be used. This caused partitions which possibly matched one or more of the previous
partitioning columns to be pruned away, leaving partitions that matched only the last column of the
partitioning key.
This issue was triggered when both of the following conditions were met:
1. The columns making up the table's partitioning key were used in the same order as in the partitioning
key definition by a SELECT statement's WHERE clause as in the column definitions;
166
MySQL 5.6 Release Notes
2. The WHERE condition used with the last column of the partitioning key was satisfied only by a single
value, while the condition testing some previous column from the partitioning key was satisfied by a
range of values.
An example of a statement creating a partitioned table and a query against this for which the issue
described above occurred is shown here:
CREATE TABLE t1 (
c1 INT,
c2 INT,
PRIMARY KEY(c2, c1)
) PARTITION BY KEY() # Use primary key as partitioning key
PARTITIONS 2;
SELECT * FROM t1 WHERE c2 = 2 AND c1 <> 2;
This issue is resolved by ensuring that partition pruning skips any remaining partitioning key columns
once a partition key column that cannot be used in pruning is encountered. (Bug #14342883)
• Partitioning: The buffer for the row currently read from each partition used for sorted reads was
allocated on open and freed only when the partitioning handler was closed or destroyed. For SELECT
statements on tables with many partitions and large rows, this could cause the server to use excessive
amounts of memory.
This issue has been addressed by allocating buffers for reads from partitioned tables only when they are
needed and freeing them immediately once they are no longer needed. As part of this fix, memory is now
allocated for reading from rows only in partitions that have not been pruned (see Partition Pruning). (Bug
#13025132)
References: See also: Bug #11764622, Bug #14537277.
• Replication; Microsoft Windows: On 64-bit Windows platforms, values greater than 4G for the
max_binlog_cache_size and max_binlog_stmt_cache_size system variables were truncated to
4G. This caused LOAD DATA INFILE to fail when trying to load a file larger than 4G in size, even when
max_binlog_cache_size was set to a value greater than this. (Bug #13961678)
• Replication: Updates writing user variables whose values were never set on a slave while using -replicate-ignore-table could cause the slave to fail. (Bug #14597605)
References: This issue is a regression of: Bug #14275000.
• Replication: A manually created file named slave_worker_info in the MySQL Server's data
directory could be mistaken for the actual relay log info file. In addition, when the number of workers
(slave_parallel_workers server system variable) was decreased, the corresponding info files were
not removed as expected. (Bug #14578740)
References: See also: Bug #13804728, Bug #14550905, Bug #14550945.
• Replication: With relay_log_info_repository=FILE and slave_parallel_workers greater
than 0, changing the relay log info repository type to TABLE and restarting the slave mysqld caused a
subsequent START SLAVE statement to crash the slave. (Bug #14550945)
References: See also: Bug #13804728, Bug #14550905, Bug #14578740.
• Replication: When the number of multi-threaded slave workers (as determined by setting
the slave_parallel_workers server system variable) was changed when using
167
MySQL 5.6 Release Notes
relay_log_info_repository=TABLE, the mysql.slave_worker_info table did not reflect the
change. (Bug #14550905)
References: See also: Bug #13804728, Bug #14550945, Bug #14578740.
• Replication: Using COM_BINLOG_DUMP_GTID with incorrect data could cause the server to crash. (Bug
#14509140)
• Replication: Executing the SQL_THREAD_WAIT_AFTER_GTIDS() function without binary logging
enabled could cause the server to crash. (Bug #14457883)
• Replication: An internal routine in the MySQL Replication code removed elements from a hash used
to store a mapping between databases and worker threads at the same time that the hash was being
iterated over. This could cause an unintended reordering of the has elements and thus possibly to
incorrect results from routines using this hash. (Bug #14381701)
References: See also: Bug #13864642.
• Replication: The names of the binary log and relay log Performance Schema mutexes were mistakenly
changed to names that differed from the MySQL 5.5 names. The names have been reverted to those
used in MySQL 5.5. (Bug #14366314)
• Replication: When setting up replication between a master and a slave which was using --masterinfo-repository=TABLE, the mysql.slave_master_info table was not updated the first time that
START SLAVE was issued. (Bug #14298750)
References: See also: Bug #13858841.
• Replication: The --disable-gtid-unsafe-statements option caused any nontransactional
DML statement involving temporary tables to be rejected with an error even with binlog_format set
explicitly to ROW, in spite of the fact that they are not written to the binary log in this case. Now, such
statements are allowed when using row-based logging, as long as any nontransactional tables affected
by the statements are also temporary tables. (Bug #14272627)
• Replication: When using multi-threaded slaves, --replicate-rewrite-db rules were not honored
while assigning databases to slave worker threads, which could cause statements to be executed out of
order when this option was used. This could result in a slave that was inconsistent with the master. (Bug
#14232958)
• Replication: mysql_upgrade failed when the server was running with gtid_mode=ON and -disable-gtid-unsafe-statements because the MySQL system tables are stored using MyISAM.
This problem is fixed by changing the default logging behavior for mysql_upgrade; logging is now
disabled by default. (Actions taken by mysql_upgrade depend on the server version, and thus should
not be replicated to slaves.) To enable logging, you can execute mysql_upgrade using the --writebinlog option. (Bug #14221043, Bug #13833710)
• Replication: The initialization and usage of a number of internal programming objects relating to GTIDs
did not work properly with PERFORMANCE_SCHEMA. (Bug #14152637)
• Replication: The scheduler for multi-threaded slaves did not take into account databases implicitly
involved in operations through foreign key dependencies, which could lead to a temporary loss of
consistency on the slave. To avoid this problem, replication events on the master that invoke foreign
key relationships between table is different databases are now marked in such a way that they can be
scheduled sequentially to avoid race conditions and thereby inconsistency. However, this can adversely
affect performance. (Bug #14092635)
• Replication: When using a multi-threaded slave, the repository type employed for the relay log info log
was not always used automatically for worker repositories as expected. (Bug #13804728)
168
MySQL 5.6 Release Notes
References: See also: Bug #14550905, Bug #14550945, Bug #14578740.
• Replication: It was possible for the multi-threaded slave coordinator to leak memory when the slave was
stopped while waiting for the next successful job to be added to the worker queue. (Bug #13635612)
• Replication: The Master_id column of the mysql.slave_master_info and
mysql.slave_relay_log_info tables showed the slave's server ID instead of the master's server
ID. (Bug #12344346)
• Replication: Statements such as UPDATE ... WHERE primary_key_column = constant LIMIT
1 are flagged as unsafe for statement-based logging, despite the fact that such statements are actually
safe. In cases where a great many such statements were run, this could lead to disk space becoming
exhausted do to the number of such false warnings being logged. To prevent this from happening, a
warning suppression mechanism is introduced. This warning suppression acts as follows: Whenever the
50 most recent ER_BINLOG_UNSAFE_STATEMENT warnings have been generated more than 50 times
in any 50-second period, warning suppression is enabled. When activated, this causes such warnings
not to be written to the error log; instead, for each 50 warnings of this type, a note is written to the error
log stating The last warning was repeated N times in last S seconds. This continues
as long as the 50 most recent such warnings were issued in 50 seconds or less; once the number of
warnings has decreased below this threshold, the warnings are once again logged normally.
The fix for this issue does not affect how these warnings are reported to MySQL clients; a warning
is still sent to the client for each statement that generates the warning. This fix also does not make
any changes in how the safety of any statement for statement-based logging is determined. (Bug
#11759333, Bug #51638)
References: See also: Bug #11751521, Bug #42415.
• ALTER TABLE ... DROP FOREIGN KEY that did not name the foreign key to be dropped caused a
server crash. Now the foreign key name is required. (Bug #14530380)
• In-place ALTER TABLE operations for InnoDB tables could raise an assertion attempting to acquire a
lock. (Bug #14516798)
• mysql_secure_installation did not work if old_passwords was set to 2 (use the
sha256_password authentication plugin). (Bug #14506073)
• Index condition pushdown in conjunction with descending index range scan caused a performance
regression. (Bug #14503142)
• Item_cache_str::save_in_field() dereferenced a null pointer if the cached value was NULL.
(Bug #14501403)
• A query with GROUP BY ... WITH ROLLUP comparing a grouping column using the IN operator
caused an assertion to be raised. (Bug #14500792)
• In debug builds, with semi-join enabled, GROUP BY ... WITH ROLLUP that did not use a temporary
table could cause a server crash. (Bug #14499409)
• An assertion was raised when using the join cache for a query that contained an IN subquery query with
a subquery that is expected to return a single row but returned more than one. (Bug #14499331)
• The optimizer could raise an assertion when grouping and sorting in descending order on an indexed
column. (Bug #14498999)
• Polygons with holes could cause a server crash for spatial operations. (Bug #14497827)
169
MySQL 5.6 Release Notes
• For complex conditions, the optimizer could produce an incorrect range construction and return incorrect
query results. (Bug #14497598)
• In mysql_com.h, the CLIENT_CONNECT_ATTRS and CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA
symbols incorrectly were defined as the same value. (Bug #14482472)
• The Threads_running status variable was not updated properly. (Bug #14471011)
• GROUP_CONCAT() with DISTINCT or ORDER BY on GEOMETRY values caused a server crash. (Bug
#14468106)
• With a password policy of STRONG and a password of 100 characters or more,
VALIDATE_PASSWORD_STRENGTH() could cause a server crash. (Bug #14458293)
• PASSWORD(NULL) and OLD_PASSWORD(NULL) could cause a server crash. (Bug #14458217)
• The explicit_defaults_for_timestamp system variable was not visible (for example, with SHOW
VARIABLES), so it was not possible to make runtime decisions based on its value. (Bug #14409088)
• When resolving outer fields, Item_field::fix_outer_fields() creates new Item_refs for each
execution of a prepared statement, so these must be allocated in the runtime memroot. The memroot
switching before resolving JOIN::having caused these to be allocated in the statement root, leaking
memory for each prepared statement execution. (Bug #14409015)
• An ALTER TABLE for an InnoDB table that attempted to add an index and also change the nullability of
a column participating in that index raised an assertion. (Bug #14404635)
• For debug builds, if one session used a DDL statement to alter an InnoDB table, another session could
raise an assertion failure if it had a pre-alter consistent snapshot of the table. (Bug #14365043)
• The result set could contain extra rows for queries on MyISAM tables that used the
SQL_BUFFER_RESULT modifier and a subquery. (Bug #14348858)
• The --server-public-key option for mysql and mysqltest has been renamed to --serverpublic-key-path to reflect that it refers to a file and for consistency with related server-side variable
naming. Also, this option now is available only if MySQL was built with OpenSSL (not yaSSL) because
yaSSL does not support the necessary RSA encryption. (Bug #14348721)
• The RPM spec file now also runs the test suite on the new binaries, before packaging them. (Bug
#14318456)
• Inside a stored program, references to stored program variables in XML functions such as
ExtractValue() failed after the first execution of the stored program. (Bug #14317442)
• The Performance Schema used listed the nanosecond timer by default for stages and statements in the
setup_timers table. But if this timer was not available on a given platform (such as Windows), timing
for stages and statements failed to work. Now the idle, stage, and statement timers used the preferred
timers if they are available, but alternate timers if not. (Bug #14298586)
• Some queries for which the optimizer used index condition pushdown in conjunction with ref access
could be very slow if the index was read in descending order. (Bug #14287654, Bug #14503142)
• Queries executed using MaterializeScan semi-join strategy and a materialized subquery could return too
many rows. (Bug #14272788)
• A LooseScan semi-join could return duplicate rows from the outer table. (Bug #14271594)
• The Performance Schema generated different digests for a statement before and after selecting a
database. (Bug #14256311)
170
MySQL 5.6 Release Notes
• The Performance Schema digest-generation code could fail with a race condition. (Bug #14250296)
• The server did not build with gcc 4.7. (Bug #14238406)
• An optimizer trace could crash attempting to print freed subquery items. (Bug #14238404)
• With semi-join optimization enabled, subqueries in the WITH CHECK OPTION clause of view definitions
were evaluated incorrectly. (Bug #14230177)
• ALTER SERVER, CREATE SERVER, and DROP SERVER with an empty server name caused a server
crash. (Bug #14220942)
• ALTER TABLE with DISCARD TABLESPACE or IMPORT TABLESPACE did not acquire a sufficiently
strong metadata lock to prevent a concurrent ALTER TABLE statement with ADD or DROP from modifying
the tablespace. This could result in warnings or raise an assertion. (Bug #14213236)
• WEIGHT_STRING() could crash if given a bad flags argument. (Bug #14211236)
• REQUIRE ISSUER clauses for GRANT statements were not rewritten properly for logging and caused a
server crash. (Bug #14211069)
• If a call to socket() failed, the Performance Schema created instrumentation for it anyway. (Bug
#14209598)
• Some queries with a HAVING clause with a function that referred to a function in the WHERE list with a
subquery as parameter caused an assertion to be raised. (Bug #14209318)
• String allocation could cause Valgrind warnings. (Bug #14201818)
• For queries that used range access, the optimizer could read uninitialized data, resulting in Valgrind
warnings. (Bug #14200538)
• mysql_upgrade did not set the STATS_PERSISTENT=0 table option for InnoDB tables in the mysql
database. (Bug #14195056)
• In debug builds, the optimizer raised an unnecessary (too strict) assertion about MyISAM key lengths.
(Bug #14179461)
• Join processing could attempt to clean up a temporary table that had not been instantiated, causing a
server crash. (Bug #14168270)
• Incorrect internal conversion of string-format dates could cause a server crash. (Bug #14167911)
• For JSON-format EXPLAIN statements, derived tables were not handled properly and caused a server
crash. (Bug #14167499)
• In debug builds, comparisons for strings that had the ucs2_unicode_520_ci collation could raise an
assertion. (Bug #14161973)
• In-place ALTER TABLE did not work for a table with a GEOMETRY column, even if the alteration did not
involve that column. (Bug #14140927)
• For nonexistent files, the Performance Schema file I/O instrumentation sometimes did extra work or was
subject to instrumentation leaks. (Bug #14113704)
• Small sort_buffer_size values could result in a server crash. (Bug #14111180)
• Within a trigger, references to a temporary table used during the query execution process could end up
pointing to nonexisting fields on subsequent executions, causing a server crash. (Bug #14105951)
171
MySQL 5.6 Release Notes
• Negative values could be erroneously reported for some columns in the
buffer_pool_pages_in_flush row in the information_schema.innodb_metrics table. (Bug
#14090287)
• JSON-format EXPLAIN statements could raise an assertion or cause the server to hang for statements
with an impossible-WHERE clause and subqueries in ORDER BY or GROUP BY clauses. (Bug #14084642)
• The FirstMatch strategy for semi-joins produced incorrect results for some queries with multiple inner
tables. (Bug #14081638)
• With materialization and semi-joins enabled, some queries with an OR condition could produce incorrect
results. (Bug #14075016)
• In-place ALTER TABLE did not handle autopartitioning storage engines such as NDB. (Bug #14063233)
• RELEASE SAVEPOINT did not have sufficient checks for the XA transaction state to prevent a savepoint
from being released while the transaction was in a prepared state. (Bug #14062726)
• Improper error handling for CREATE SERVER, DROP SERVER, and ALTER SERVER could raise an
assertion. (Bug #14061851)
• Improper initialization by spatial functions could cause a server crash the first time they were invoked
following server startup. (Bug #14015762)
• For JSON-format EXPLAIN statements, improper handling of subqueries could cause an assertion to be
raised. (Bug #13956275)
• SELECT on a partitioned table that used a join buffer could cause a server crash. (Bug #13949549)
• Polygon sorting by spatial functions could be done incorrectly and cause a server crash. (Bug
#13938850)
• For DELETE statements, WHERE clause row retrieval that should access only the index tree could raise
an assertion. (Bug #13919180)
• The argument for LIMIT must be an integer, but if the argument was given by a placeholder in a
prepared statement, the server did not reject noninteger values such as '5'. (Bug #13868860)
• Some arguments could cause ST_Buffer() to crash. (Bug #13832749, Bug #13833019)
• Queries that used the ST_Contains and Within() functions yielded incorrect results when argument
columns had a spatial index. (Bug #13813064)
• CHECK TABLE and REPAIR TABLE could crash if a key definition differed in the .frm and .MYI files of
a MyISAM table. Now the server produces an error. (Bug #13555854)
• The optimizer used a full index scan for cases for which a loose index scan was preferable. (Bug
#13464493)
References: This issue is a regression of: Bug #12540545.
• COUNT(DISTINCT(SELECT 1)) could be evaluated incorrectly if the optimizer used Loose Index Scan.
(Bug #13444084)
References: See also: Bug #13813126.
• A query for a FEDERATED table could return incorrect results when the underlying table had a compound
index on two columns and the query included an AND condition on the columns. (Bug #12876932)
172
MySQL 5.6 Release Notes
• In debug builds, an InnoDB assertion was overly aggressive about prohibiting an open range. (Bug
#66513, Bug #14547952)
• Starting the server with --bind-address=* is supposed to cause the server to accept TCP/IP
connections on all server host IPv6 and IPv4 interfaces if the server host supports IPv6, or TCP/IP
connections on all IPv4 addresses otherwise. But the server sometimes did not correctly detect when
IPv6 was not supported, and failed to start. (Bug #66303, Bug #14483430)
• Queries with ALL over a UNION could return an incorrect result if the UNION result contained NULL. (Bug
#65902, Bug #14329235)
• In-place ALTER TABLE incorrectly handled indexes using key prefixes by using a copy algorithm. (Bug
#65865, Bug #14304973)
• If the server was started with secure_auth disabled, it did not produce a warning that this is a
deprecated setting. (Bug #65462, Bug #14136937)
• The ST_Contains() and Within() functions yielded an incorrect result when used on a column with
a SPATIAL index. (Bug #65348, Bug #14096685)
• For some queries, the optimizer used index_merge access method when this was more work than ref
access. (Bug #65274, Bug #14120360)
• The GeomFromWKB() function did not return NULL if the SRID argument was NULL, and non-NULL SRID
values were not included in the converted result. (Bug #65094, Bug #13998446)
• Internal temporary MyISAM tables were unnecessarily registered in an open-table list protected by a
global mutex, causing excessive mutex contention. (Bug #65077, Bug #14000697)
• In prepared statements, MYSQL_TYPE_DATE parameters when converted to an integer were handled
as MYSQL_TYPE_DATETIME values and the conversion produced incorrect results. (Bug #64667, Bug
#13904869)
• “Illegal mix of collation” errors were returned for some operations between strings that should have been
legal. (Bug #64555, Bug #13812875)
• COUNT(DISTINCT(IF ...)) could be evaluated incorrectly if the optimizer used Loose Index Scan.
(Bug #64445, Bug #13813126)
References: See also: Bug #13444084.
• The argument to the --ssl-key option was not verified to exist and be a valid key. The resulting
connection used SSL, but the key was not used. (Bug #62743, Bug #13115401)
• With statement-based binary logging, stored routines that accessed but did not modify tables took too
strong a lock for the tables, unnecessarily blocking other statements that also accessed those tables.
(Bug #62540, Bug #13036505)
• mysqlhotcopy failed for databases containing views. (Bug #62472, Bug #13006947, Bug #12992993)
• Adding a LIMIT clause to a query containing GROUP BY and ORDER BY could cause the optimizer to
choose an incorrect index for processing the query, and return more rows than required. (Bug #54599,
Bug #11762052)
• mysqlbinlog did not accept input on the standard input when the standard input was a pipe. (Bug
#49336, Bug #11757312)
• There was a performance regression for queries that used GROUP BY and COUNT(DISTINCT). (Bug
#49111, Bug #11757108)
173
MySQL 5.6 Release Notes
• mysqldump could dump views and the tables on which they depend in such an order that errors
occurred when the dump file was reloaded. (Bug #44939, Bug #11753490)
Changes in MySQL 5.6.6 (2012-08-07, Milestone 9)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
• Binary Logging
• Configuration Notes
• Performance Schema Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
Binary Logging
• Performance: The server now implements group commit for the binary log: Multiple commits are
grouped in memory, then written and flushed to disk as a group rather than individually. This reduces
the number of writes and flushes, improving performance of binary logging. Group commit works for all
storage engines. InnoDB implements some optimizations to take advantage of group commit capability.
These system variables were added in conjunction with group commit:
• binlog_order_commits: Whether to commit transactions in the same order they are written to the
binary log or permit them to be committed in parallel.
• binlog_max_flush_queue_time: How long in microseconds to keep reading transactions from the
flush queue before proceeding with the group commit.
• innodb_flush_log_at_timeout: Write and flush logs every N seconds.
Configuration Notes
• This MySQL release implements changes to the default values of several server parameters. The
motivation for these changes is to provide better out-of-box performance and to reduce the need for
database administrators to change settings manually. These changes are subject to revision in future
releases as we gain feedback. (See Changes to Server Defaults.)
In some cases, a parameter has a different fixed default value. In other cases, the server autosizes a
parameter at startup using a formula based on other related parameters or server host configuration,
rather than using a fixed value. For example, the setting for back_log is its previous default of 50,
adjusted up by an amount proportional to the value of max_connections. The idea behind autosizing
is that when the server has information available to make a decision about a parameter setting likely to
be better than a fixed default, it will.
174
MySQL 5.6 Release Notes
The following table summarizes changes to defaults. For variables that are autosized, the main variable
description provides additional detail about the sizing algorithm. See Server System Variables, and
InnoDB Startup Options and System Variables. Any of these default settings can be overridden by
specifying an explicit value at server startup.
Parameter
Old Default
New Default
back_log
50
Autosized using max_connections
binlog_checksum
NONE
CRC32
--binlog-row-event-max-size
1024
8192
flush_time
1800 (on
Windows)
0
innodb_autoextend_increment
8
64
innodb_buffer_pool_instances
1
8 (platform dependent)
innodb_checksum_algorithm
INNODB
CRC32
innodb_concurrency_tickets
500
5000
innodb_file_per_table
0
1
innodb_old_blocks_time
0
1000
innodb_open_files
300
Autosized using innodb_file_per_table,
table_open_cache
innodb_stats_on_metadata
ON
OFF
join_buffer_size
128KB
256KB
max_allowed_packet
1MB
4MB
max_connect_errors
10
100
performance_schema
OFF
ON
performance_schema_events_waits_history_long_size
10000
Autosized
performance_schema_events_waits_history_size
10
Autosized
performance_schema_max_cond_instances
1000
Autosized
performance_schema_max_file_instances
10000
Autosized
performance_schema_max_mutex_instances
1000000
Autosized
performance_schema_max_rwlock_instances
1000000
Autosized
performance_schema_max_table_handles
100000
Autosized
performance_schema_max_table_instances
50000
Autosized
performance_schema_max_thread_instances
1000
Autosized
sql_mode
'' (empty
string)
NO_ENGINE_SUBSTITUTION
sync_master_info
0
10000
sync_relay_log
0
10000
sync_relay_log_info
0
10000
With regard to compatibility with previous releases, the most important changes are:
• innodb_file_per_table is enabled (previously disabled)
175
MySQL 5.6 Release Notes
• innodb_checksum_algorithm is CRC32 (previously INNODB)
• binlog_checksum is CRC32 (previously NONE)
Therefore, if you are upgrading an existing MySQL installation, have not already changed the values of
these parameters from their previous defaults, and backward compatibility is a concern, you may want
to explicitly set these parameters to their previous defaults. For example, put these lines in the server
option file:
[mysqld]
innodb_file_per_table=0
innodb_checksum_algorithm=INNODB
binlog_checksum=NONE
Those settings preserve compatibility as follows:
• With the new default of innodb_file_per_table enabled, ALTER TABLE operations following an
upgrade will move InnoDB tables that are in the system tablespace to individual .ibd files. Using
innodb_file_per_table=0 will prevent this from happening.
• Setting innodb_checksum_algorithm=INNODB permits binary downgrades after upgrading to this
release. With a setting of CRC32, InnoDB would use checksumming that older MySQL versions cannot
use.
• With binlog_checksum=NONE, the server can be used as a replication master without causing
failure of older slaves that do not understand binary log checksums.
Performance Schema Notes
• The Performance Schema is now enabled by default (the performance_schema system variable is
enabled by default). To disable it, set performance_schema=off at server startup.
In addition, the Performance Schema now automatically sizes the values of several of its parameters at
server startup if they are not set explicitly. For example, it sizes the parameters that control the sizes of
the events waits tables this way. To see which parameters are sized under this policy, use mysqld -verbose --help and look for those with a default value of −1, or see Performance Schema System
Variables.
For each autosized parameter that is not set at server startup (or is set to −1), the Performance Schema
determines how to set its value based on the value of the following system values, which are considered
as “hints” about how you have configured your MySQL server:
max_connections
open_files_limit
table_definition_cache
table_open_cache
To override autosizing for a given parameter, set it a value other than −1 at startup. In this case, the
Performance Schema assigns it the specified value.
At runtime, SHOW VARIABLES displays the actual values that autosized parameters were set to.
If the Performance Schema is disabled, its autosized parameters remain set to −1 and SHOW
VARIABLES displays −1.
Security Notes
176
MySQL 5.6 Release Notes
• These security improvements were implemented:
• MySQL now provides a method for storing authentication credentials encrypted in an option file named
.mylogin.cnf. To create the file, use the mysql_config_editor utility. The file can be read later
by MySQL client programs to obtain authentication credentials for connecting to a MySQL server.
mysql_config_editor writes the .mylogin.cnf file using encryption so the credentials are not
stored as clear text, and its contents when decrypted by client programs are used only in memory.
In this way, passwords can be stored in a file in non-cleartext format and used later without ever
needing to be exposed on the command line or in an environment variable. For more information, see
mysql_config_editor — MySQL Configuration Utility.
The .mylogin.cnf file can contain multiple sets of options, known as “login paths.” This makes it
easy to set up multiple “personalities” for connecting to different MySQL servers. Any of these can
be selected by name later using the --login-path option when you invoke a client program. See
Command-Line Options that Affect Option-File Handling.
• MySQL now supports stronger encryption for user account passwords, available through an
authentication plugin named sha256_password that implements SHA-256 password hashing. This
plugin is built in, so it is always available and need not be loaded explicitly. For more information,
including instructions for creating accounts that use SHA-256 passwords, see SHA-256 Pluggable
Authentication.
Other changes associated with the introduction of the sha256_password plugin:
• The old_passwords system variable previously permitted values of 1 or 0 to control whether “old”
or “new” MySQL native password hashing was used by the CREATE USER and GRANT statements
and the PASSWORD() function. Now old_passwords permits a value of 2 to select use of SHA-256
password hashing.
Note
Previously, old_passwords permitted values of OFF or ON as synonyms for
0 or 1. That is no longer true.
• SHA-256 password hashing (old_passwords=2) uses a random salt value, which makes the
result from PASSWORD() nondeterministic. Consequently, statements that use this function are no
longer safe for statement-based replication and cannot be stored in the query cache.
• If MySQL is built with OpenSSL, RSA encryption can be used to transmit passwords
during the client connection process. The sha256_password_private_key_path and
sha256_password_public_key_path system variables permit the private and public key files to
be named on the server side. The Rsa_public_key status variable displays the public key value.
The mysql and mysqltest clients support a --server-public-key option permitting the public
key file to be specified explicitly when connecting to the server. (This option is implemented through
a new MYSQL_SERVER_PUBLIC_KEY option to the mysql_options() C API function.)
MySQL Connector support: Connectors that use the C client library should work with
sha256_password with no changes. Connectors that implement the authentication process for
themselves must be updated to account for changes in the client/server protocol.
• The server now has a --default-authentication-plugin option to specify the default
plugin to associate with new accounts for which no plugin is named explicitly. Permitted values
are mysql_native_password (use MySQL native passwords; this is the default value) and
sha256_password (use SHA-256 passwords). This option also changes the initial old_passwords
value to be consistent with the password hashing method required by the default plugin, if necessary.
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MySQL 5.6 Release Notes
Note
If you use this option to change the default authentication method to a value
other than mysql_native_password, clients older than MySQL 5.5.7 will no
longer be able to connect because they will not understand the change to the
authentication protocol.
• The mysql.user table now has a password_expired column to enable DBAs to expire account
passwords and require users to reset their password. The default password_expired value is 'N',
but can be set to 'Y' with the new ALTER USER statement. After an account's password has been
expired, all operations performed by the account in subsequent connections to the server result in
an error until the user issues a SET PASSWORD statement to establish a new account password. For
more information, see ALTER USER Syntax, and Password Expiration and Sandbox Mode.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate this change into the mysql database.
Caution
Update: ALTER USER also set the Password column to the empty string,
so do not use this statement in 5.6.6. This problem has been fixed in MySQL
5.6.7.
• MySQL now has provision for checking password security:
• In statements that assign a password supplied as a cleartext value, the value is checked
against the current password policy and rejected if it is weak (the statement returns an
ER_NOT_VALID_PASSWORD error). This affects the CREATE USER, GRANT, and SET PASSWORD
statements. Passwords given as arguments to the PASSWORD() and OLD_PASSWORD() functions
are checked as well.
• The strength of potential passwords can be assessed using the new
VALIDATE_PASSWORD_STRENGTH() SQL function, which takes a password argument and returns
an integer from 0 (weak) to 100 (strong).
Both capabilities are implemented by the validate_password plugin. If the plugin is not installed,
the affected statements and PASSWORD() and OLD_PASSWORD() work as before (no password
checking), and VALIDATE_PASSWORD_STRENGTH() always returns 0.
The validate_password plugin also implements a set of system variables corresponding to the
parameters that control password checking. If the plugin is installed, you can modify these variables to
configure the password policy.
The validate_password plugin is written using the MySQL plugin API, which has been extended to
support writing password-validation plugins.
For more information, see The Password Validation Plugin. For information about writing passwordchecking plugins, see Writing Password-Validation Plugins.
• mysql_upgrade now produces a warning if it finds user accounts with passwords hashed with
the older pre-4.1 hashing method. Such accounts should be updated to use more secure password
hashing. See Password Hashing in MySQL
(Bug #65461, Bug #14136939)
178
MySQL 5.6 Release Notes
• For the WITH_SSL CMake option, no is no longer a permitted value or the default value. The default is
now bundled. Consequently, MySQL now is always built with SSL support.
Functionality Added or Changed
• Incompatible Change: It is now explicitly disallowed to assign the value DEFAULT to stored procedure
or function parameters or stored program local variables (for example with a SET var_name =
DEFAULT statement). This was not previously supported, or documented as permitted, but is flagged as
an incompatible change in case existing code inadvertently used this construct. It remains permissible to
assign DEFAULT to system variables, as before, but assigning DEFAULT to parameters or local variables
now results in a syntax error.
After an upgrade to MySQL 5.6.6 or later, existing stored programs that use this construct produce a
syntax error when invoked. If a mysqldump file from 5.6.5 or earlier is loaded into 5.6.6 or later, the load
operation fails and affected stored program definitions must be changed.
• Incompatible Change: The --safe-mode server option has been removed.
• Important Change; Partitioning: MySQL nows supports partition lock pruning, which allows for many
DDL and DML statements against partitioned tables using MyISAM (or another storage engine that
employs table-level locking) to lock only those partitions directly affected by the statement. These
statements include (but are not limited to) many SELECT, SELECT ... PARTITION, UPDATE,
REPLACE, INSERT, and other statements. This enhancement improves especially the performance of
many such statements when used with tables having many (32 or more) partitions. For a complete list of
affected statements with particulars, and other information, see Partitioning and Locking. (Bug #37252,
Bug #11748732)
• Important Change; Replication: It is now possible, in the event that a multi-threaded slave fails while
running with the --relay-log-recovery option, to switch it safely to single-threaded mode despite
the presence of any gaps with unprocessed transactions in the relay log. To accomplish this, you can
now use START SLAVE [SQL_THREAD] UNTIL SQL_AFTER_MTS_GAPS to cause the slave SQL
threads to run until no more such gaps are found in the relay log. Once this statement has completed,
you can change the slave_parallel_workers system variable, and (if necessary) issue a CHANGE
MASTER TO statement before restarting the slave. (Bug #13893363)
References: See also: Bug #13893310.
• Important Change; Replication: INSERT ON DUPLICATE KEY UPDATE is now marked as unsafe
for statement-based replication if the target table has more than one primary or unique key. For more
information, see Determination of Safe and Unsafe Statements in Binary Logging. (Bug #58637, Bug
#11765650, Bug #13038678)
• Important Change; Replication: The SHOW BINARY LOGS statement (and its equivalent SHOW
MASTER LOGS) may now be executed by a user with the REPLICATION CLIENT privilege. (Formerly,
the SUPER privilege was necessary to use either form of this statement.)
• Important Change: INSERT DELAYED is now deprecated, and will be removed in a future release. Use
INSERT (without DELAYED) instead. (Bug #13985071)
• Important Change: In MySQL, the TIMESTAMP data type differs in nonstandard ways from other data
types:
• TIMESTAMP columns not explicitly declared with the NULL attribute are assigned the NOT NULL
attribute. (Columns of other data types permit NULL values if not explicitly declared with the NOT NULL
attribute.) Setting such a column to NULL sets it to the current timestamp.
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MySQL 5.6 Release Notes
• The first TIMESTAMP column in a table, if not declared with the NULL attribute or an explicit DEFAULT
or ON UPDATE attribute, is automatically assigned the DEFAULT CURRENT_TIMESTAMP and ON
UPDATE CURRENT_TIMESTAMP attributes.
• TIMESTAMP columns following the first one, if not declared with the NULL attribute or an explicit
DEFAULT attribute, are automatically assigned DEFAULT '0000-00-00 00:00:00' (the “zero”
timestamp). For inserted rows that specify no explicit value for such a column, the column is assigned
'0000-00-00 00:00:00' and no warning occurs.
Those nonstandard behaviors remain the default for TIMESTAMP but now are deprecated and this
warning appears at startup:
[Warning] TIMESTAMP with implicit DEFAULT value is deprecated.
Please use --explicit_defaults_for_timestamp server option (see
documentation for more details).
As indicated by the warning, to turn off the nonstandard behaviors, enable the new
explicit_defaults_for_timestamp system variable at server startup. With this variable enabled,
the server handles TIMESTAMP as follows instead:
• TIMESTAMP columns permit NULL values if not explicitly declared with the NOT NULL attribute. Setting
such a column to NULL sets it to NULL, not the current timestamp.
• No TIMESTAMP column is assigned the DEFAULT CURRENT_TIMESTAMP or ON UPDATE
CURRENT_TIMESTAMP attributes automatically. Those attributes must be explicitly specified.
• TIMESTAMP columns declared as NOT NULL and without an explicit DEFAULT attribute are treated as
having no default value. For inserted rows that specify no explicit value for such a column, the result
depends on the SQL mode. If strict SQL mode is enabled, an error occurs. If strict SQL mode is not
enabled, the column is assigned the implicit default of '0000-00-00 00:00:00' and a warning
occurs. This is similar to how MySQL treats other temporal types such as DATETIME.
To upgrade servers used for replication, upgrade the slaves first, then the master. Replication
between the master and its slaves should work provided that all use the same value of
explicit_defaults_for_timestamp:
1. Bring down the slaves, upgrade them, configure them with the desired value of
explicit_defaults_for_timestamp, and bring them back up.
The slaves will recognize from the format of the binary logs received from the master that the master
is older (predates the introduction of explicit_defaults_for_timestamp) and that operations
on TIMESTAMP columns coming from the master use the old TIMESTAMP behavior.
2. Bring down the master, upgrade it, and configure it with the same
explicit_defaults_for_timestamp value used on the slaves, and bring it back up.
(Bug #63034, Bug #13344629, Bug #55131, Bug #11762529)
• Important Change: The YEAR(2) data type is now deprecated because it is problematic. YEAR(2)
columns in existing tables are treated as before, but YEAR(2) in new or altered tables are converted
to YEAR(4). Support for YEAR(2) will be removed entirely in a future MySQL release. For more
information, see YEAR(2) Limitations and Migrating to YEAR(4).
• Performance; InnoDB: Many DDL operations on InnoDB tables can now be performed online, without
making the tables unavailable for queries. Some operations, such as creating or dropping indexes, even
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MySQL 5.6 Release Notes
allow DML statements (INSERT, UPDATE, DELETE) on the table while the operation is in progress. A
single online DDL operation can also take the place of a sequence of statements, such as several DROP
INDEX statements, ALTER TABLE ... ADD COLUMN, and then several CREATE INDEX statements.
See InnoDB and Online DDL for full details.
An additional effect of this change occurs for consistent-read transactions that try to reread data from a
table which was changed by ALTER TABLE in another session. Instead of receiving an empty set, the
transaction will receive an error (ER_TABLE_DEF_CHANGED, “Table definition has changed, please retry
transaction”). (Bug #58368, Bug #11765404, Bug #11872643, Bug #12325508, Bug #11765266, Bug
#60689)
• Performance; InnoDB: The persistent statistics feature for InnoDB tables is now enabled
by default, and can be controlled at the level of individual tables. This feature involves the
configuration options innodb_stats_persistent, innodb_stats_auto_recalc, and
innodb_stats_persistent_sample_pages, and the clauses STATS_PERSISTENT,
STATS_AUTO_RECALC, and STATS_SAMPLE_PAGES of the CREATE TABLE and ALTER TABLE
statements. See Configuring Persistent Optimizer Statistics Parameters for usage details.
• Performance; InnoDB: The MySQL server now includes the widely used memcached in-memory
caching system, and a plugin that allows fast NoSQL-style access to InnoDB tables through the
memcached protocol. This access method avoids the overhead of SQL parsing and constructing a
query optimization plan. You can store the underlying data in a single InnoDB table, or spread it across
multiple tables. You can read and write data through both memcached and SQL. For example, you can
do fast single-key lookups through memcached get calls, and do statistical reports across all the data
through SQL.
Several configuration options let you fine-tune this system, in particular to balance raw
performance against durability and consistency of data. The main new configuration
options are daemon_memcached_option, daemon_memcached_r_batch_size,
daemon_memcached_w_batch_size, innodb_api_trx_level, innodb_api_enable_mdl, and
innodb_api_enable_binlog.
See InnoDB memcached Plugin for full details.
• InnoDB: For systems with constant heavy workloads, or workloads that fluctuate widely,
several new configuration options let you fine-tune the flushing behavior for InnoDB
tables: innodb_adaptive_flushing_lwm, innodb_max_dirty_pages_pct_lwm,
innodb_max_io_capacity (changed in subsequent point releases to innodb_io_capacity_max),
and innodb_flushing_avg_loops. These options feed into an improved formula used by the
innodb_adaptive_flushing option. For full details about improvements to flushing algorithms and
options, see Fine-tuning InnoDB Buffer Pool Flushing.
• InnoDB: InnoDB tables now support the notion of “transportable tablespaces”, allowing .ibd files to be
exported from a running MySQL instance and imported into another running instance. The FOR EXPORT
clause of the FLUSH TABLES statement writes any unsaved changes from InnoDB memory buffers to
the .ibd file. After copying the .ibd file and a separate metadata file to the other server, you can use
the DISCARD TABLESPACE and IMPORT TABLESPACE clauses of the ALTER TABLE statement to
bring the table data into a different MySQL instance.
For more information, see Copying File-Per-Table Tablespaces to Another Instance.
• InnoDB: InnoDB now supports the DATA DIRECTORY='directory' clause of the CREATE TABLE
statement, which allows you to create InnoDB file-per-table tablespaces (.ibd files) in a location
outside the MySQL data directory.
For additional information, see Creating File-Per-Table Tablespaces Outside the Data Directory.
181
MySQL 5.6 Release Notes
• Replication: The STOP SLAVE option SQL_BEFORE_GTIDS did not function correctly, and the
SQL_AFTER_GTIDS option for the same statement did not function at all. (Bug #13810456)
• Replication: Added the --slave-rows-search-algorithms option for mysqld, which determines
the search algorithms used for finding matches for slave updates when slave_allow_batching is
enabled, including whether or not table or index hashing is used with searches employing a primary or
unique key, some other key, or no key.
• The Performance Schema has a new system variable,
performance_schema_session_connect_attrs_size, and new status variable,
Performance_schema_session_connect_attrs_lost. The system variable is the amount of
preallocated memory per thread reserved to hold connection attribute key/value pairs. If the aggregate
size of connection attribute data sent by a client is larger than this amount, the Performance Schema
truncates the attribute data and increments the status variable. See Performance Schema Connection
Attribute Tables. (Bug #14076427)
• yaSSL was upgraded from version 1.7.2 to 2.1.4. (Bug #13713205)
References: See also: Bug #13706828.
• The optimizer's cost model for disk-sweep Multi-Read Range (DS-MRR) has been improved. The
improved cost model makes it more likely that DSMRR will be used for queries that read much data from
disk.
• Previously, the default value for the --bind-address option was 0.0.0.0, which causes the server to
accept TCP/IP connections on all server host IPv4 interfaces. To make it easier to use IPv6 connections
without special configuration, the default --bind-address value now is *. This is similar to 0.0.0.0,
but causes the server to also accept TCP/IP connections on all IPv6 interfaces if the server host
supports IPv6. (Another way to accept IPv4 and IPv6 connections is by using --bind-address=::,
but in this case an error occurs if the server host does not support IPv6.)
• It is now possible for client programs to pass connection attributes to the server in the form of
key/value pairs. Attributes are manipulated using the MYSQL_OPT_CONNECT_ATTR_RESET
and MYSQL_OPT_CONNECT_ATTR_DELETE options for the mysql_options() C API
function, and the MYSQL_OPT_CONNECT_ATTR_ADD option for the new mysql_options4()
function. Connection attributes are exposed through the session_connect_attrs and
session_account_connect_attrs Performance Schema tables.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the performance_schema database.
For more information, see C API Function Descriptions, and MySQL Performance Schema.
• Previously, for semi-join processing the outer query specification was limited to simple table scans or
inner joins using comma syntax, and view references were not possible. Now outer join and inner join
syntax is permitted in the outer query specification, and the restriction that table references must be base
tables has been lifted.
• To improve scalability by reducing contention among sessions for the global lock on the open tables
cache, the cache now can be partitioned into several smaller cache instances. A session now need
lock only one instance to access it for DML statements. This segments cache access among instances,
permitting higher performance for operations that need to use the cache when many there are many
sessions accessing tables. (DDL statements still require a lock on the entire cache, but such statements
are much less frequent than DML statements.)
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MySQL 5.6 Release Notes
A new system variable, table_open_cache_instances, permits control over the number of cache
instances. Each instance has a size of table_open_cache / table_open_cache_instances. By
default, the number of instances is 1.
Three new status variables provide information about the operation of the open tables cache.
Table_open_cache_hits and Table_open_cache_misses indicate the number of hits and
misses or lookups in the cache. Table_open_cache_overflows indicates how many times, after a
table is opened or closed, an instance has an unused entry and the size of the instance is larger than
table_open_cache / table_open_cache_instances.
• The generic “procedure API” has been removed from the server. This was formerly present as a means
of writing server procedures, but went unused except for PROCEDURE ANALYSE(). Removing the
interface simplifies aspects of the internal procedure representation that were related to code no longer
in the server but had a negative effect on its operation, in the sense that these aspects hindered the
ability of the optimizer to perform better on more common query types. In addition, this code hindered
future optimizer development and its removal will have benefit that development.
PROCEDURE ANALYSE() remains available, but is no longer implemented using a public interface.
(For information, see Using PROCEDURE ANALYSE.) One consequence of removing the procedure
interface is that EXPLAIN SELECT ... PROCEDURE ANALYSE() now works where previously it
produced an error.
Bugs Fixed
• Incompatible Change: Metadata was handled incorrectly for objects such as tables or views that were
used in a stored program. Metadata for each such object was gathered at the beginning of program
execution, but not updated if DDL statements modified the object during program execution (or modified
it between executions of the program if the program remained in the stored program cache). This
resulted in mismatches between the actual object structure and the structure the stored program
believed the object to have during execution, and caused problems such as data errors or server
crashes.
Now metadata changes to objects used in a stored program are detected during execution and affected
statements within the program are reparsed so that they use the updated metadata.
Example: Suppose that a stored program executes this statement in a loop and that the columns in the
table t1 are altered during loop execution:
SELECT * FROM t1;
Previously, errors occurred because program execution did not detect that SELECT * evaluates to a
different set of columns after the change. Now the table change is detected and the SELECT is reparsed
to determine the new set of columns.
Reparsing occurs for other cases as well, such as t1 being changed from a base table to a view or a
TEMPORARY table. For more information, see Caching of Prepared Statements and Stored Programs.
There is a possible incompatibility regarding the new behavior: Application code that assumed the
previous behavior and implemented a workaround may need to be changed.
Other instances of corrected problems:
• SELECT * within a stored program could fail for TEMPORARY tables created within the program using
prepared statements.
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MySQL 5.6 Release Notes
• “Unknown column” errors or bad data could result from changing the set of columns in a table used
within a stored program between executions of the program or while the table was used within a
program loop. Errors could also occur under similar circumstances for a view if the view definition was
changed, for a TEMPORARY table if the table was dropped.
• Failure of triggers to notice metadata changes in objects accessed within the program could cause
trigger malfunction.
• Failure of a stored program to notice metadata changes in objects accessed within the program could
cause replication to fail.
(Bug #61434, Bug #12652835, Bug #55678, Bug #11763018, Bug #64574, Bug #13840615, Bug
#33843, Bug #11747732, Bug #33289, Bug #11747626, Bug #33255, Bug #11747619, Bug #33000, Bug
#11747566, Bug #27011, Bug #11746530, Bug #33083, Bug #11747581, Bug #32868, Bug #11747537,
Bug #12257, Bug #11745236)
• Important Change; NDB Cluster: mysqld_safe now traps Signal 13 (SIGPIPE) so that this signal no
longer kills the MySQL server process. (Bug #33984)
• Performance; InnoDB; Partitioning: The statistics used by the optimizer for queries against partitioned
InnoDB tables were based only on the first partition of each such table, leading to use of the wrong
execution plan. (Bug #13694811)
References: This issue is a regression of: Bug #11756867.
• Performance; InnoDB: Improved the efficiency of InnoDB code with regard to CPU cache coherency.
(Bug #14034087)
• Performance; InnoDB: Improved the efficiency of the system calls to get the system time to record the
start time for a transaction. This fix reduces potential cache coherency issues that affected performance.
(Bug #13993661)
• Performance; InnoDB: Improved the algorithm related to adaptive flushing. This fix increases the rate
of flushing in cases where compression is used and the data set is larger than the buffer pool, leading to
eviction. (Bug #13990648, Bug #65061)
• Performance; InnoDB: Improved the efficiency of the COMMIT operation for InnoDB tables, by reducing
the potential for context switching and acquiring/re-acquiring mutexes while the operation is in progress.
(Bug #13989037)
• Performance; InnoDB: The order in which flushes are performed when the
innodb_flush_neighbors configuration option is enabled was improved. The algorithm makes the
neighbor-flushing technique faster on HDD storage, while reducing the performance overhead on SSD
storage. (innodb_flush_neighbors typically is not needed for SSD hardware.) (Bug #13798956)
• Performance; InnoDB: This fix improves the speed of DROP TABLE for InnoDB tables by removing
a scan of the buffer pool to remove entries for the adaptive hash index. This improvement is most
noticeable on systems with very large buffer pools and the innodb_adaptive_hash_index option
enabled. (Bug #13704145, Bug #64284)
• Performance; Replication: All changes made as part of a given transaction are cached; when the
transaction is committed, the contents of this cache are written to the binary log. When using global
transaction identifiers, the GTID identifying this transaction must be the first event among all events in
the cache belonging to the transaction.
Previously, a portion of the cache was preallocated as a buffer when the transaction began; upon
commit it was completed with a valid GTID. However, because it was not possible to perform a seek in
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MySQL 5.6 Release Notes
the cache, it was necessary to flush it to a temporary file, and then seek within this file. When the cache
buffer is not big enough to accommodate all changes comprising a given transaction, it swapped the
data to disk, then reinitialized the cache to have the buffer properly filled with the correct data again.
The buffer was actually flushed and the cache reinitialized every time a GTID event was written, even
in those cases in which all events making up a given transaction fit within the cache buffer, which could
negatively impact the performance of binary logging (and thus replication) when using GTIDs.
Now the cache is reinitialized only when it is actually necessary—in other words, only when the cache is
in fact swapped to disk.
In addition, the fix for this issue addresses a missing unlock operation when the server failed to write
an empty transaction group and reduces the amount of code needed for prepending the GTID to the
contents of the cache before flushing the cache to disk. (Bug #13877432)
References: See also: Bug #13738296.
• Performance: Within stored programs, the overhead of making statements log friendly was incurred
even when the corresponding log was not enabled. (Bug #12884336)
• Performance: The MD5() and SHA1() functions had excessive overhead for short strings. (Bug
#49491, Bug #11757443, Bug #60227, Bug #14134662)
• InnoDB; Replication: When binary log statements were replayed on the slave, the Com_insert,
Com_update, and Com_delete counters were incremented by BEGIN statements initiating transactions
affecting InnoDB tables but not by COMMIT statements ending such transactions. This affected these
statements whether they were replicated or they were run using mysqlbinlog. (Bug #12662190)
• InnoDB: Dropping an InnoDB temporary table could leave behind the .ibd file if the table was created
with the innodb_file_per_table setting enabled. On Windows systems, this could cause an
additional problem: repeated attempts to drop the file for 2000 seconds. In addition to resolving the
incorrect path name used to drop the file, this fix also limits the retry loop to 10 seconds, for example if
the file cannot be removed because it is locked by a backup process. (Bug #14169459)
• InnoDB: When importing an InnoDB tablespace representing a compressed table, unnecessary
checksum calculations were being performed. (Bug #14161424)
• InnoDB: If MySQL crashed during an ALTER TABLE t DISCARD TABLESPACE operation, it could
leave InnoDB in a state where it crashes at the next startup. The error message was:
InnoDB: Error: a record lock wait happens in a dictionary operation!
(Bug #14146981)
• InnoDB: A race condition could cause a crash during an online CREATE INDEX statement for an
InnoDB table. This bug only affected very small tables. It required a DML operation to be in progress
for the table, affecting the primary key columns, at the same time the CREATE INDEX statement was
issued. (Bug #14117641)
• InnoDB: An assertion error could occur if an XA transaction was created within a session designated as
read-only. (Bug #14108709)
• InnoDB: If a row was deleted from an InnoDB table, then another row was re-inserted with the same
primary key value, an attempt by a concurrent transaction to lock the row could succeed when it should
have waited. This issue occurred if the locking select used a WHERE clause that performed an index scan
using a secondary index. (Bug #14100254, Bug #65389)
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MySQL 5.6 Release Notes
• InnoDB: This fix improves the accuracy of the data in the INFORMATION_SCHEMA table
innodb_metrics for systems with innodb_buffer_pool_instances set to greater than 1. The
improved information applies to the number of pages flushed from the buffer pool, specifically these
entries in the table:
buffer_flush_batch_total_pages
buffer_flush_neighbor_total_pages
buffer_flush_adaptive_total_pages
buffer_flush_sync_total_pages
buffer_flush_background_total_pages
buffer_LRU_batch_total_pages
(Bug #14037167)
• InnoDB: In a transaction using the REPEATABLE READ isolation level, an UPDATE or DELETE statement
for an InnoDB table could sometimes overlook rows recently committed by other transactions. As
explained in Consistent Nonlocking Reads, DML statements within a REPEATABLE READ transaction
apply to rows committed by other transactions, even if a query could not see those rows. (Bug
#14007649, Bug #65111)
• InnoDB: During an ANALYZE TABLE statement for an InnoDB table, the server could hang (in nondebug builds), or an assertion error could occur, indicating recursive acquisition of a lock (in debug
builds). (Bug #14007109)
• InnoDB: An assertion could be raised if an InnoDB table was moved to a different database using
ALTER TABLE ... RENAME while the database was being dropped by DROP DATABASE. (Bug
#13982017)
• InnoDB: Querying the INFORMATION_SCHEMA.INNODB_TRX or related tables while the server was
running a heavy InnoDB workload could cause a crash, with messages in the error log referring to the
function fetch_data_into_cache_low. This issue arose during new feature work and only affected
MySQL 5.6. (Bug #13966453)
• InnoDB: Fixes a recently introduced issue with InnoDB persistent statistics, that could cause a crash
(non-debug builds) or assertion error (debug builds). (Bug #13946118)
• InnoDB: Including a % character in a query using an InnoDB FULLTEXT index could cause a crash.
(FULLTEXT indexes for InnoDB tables are a new feature, still under development.) (Bug #13940669,
Bug #64901)
• InnoDB: Using the KILL statement to terminate a query could cause an unnecessary message in the
error log:
[ERROR] Got error -1 when reading table table_name
(Bug #13933132)
• InnoDB: When a table was renamed, the InnoDB persistent statistics were not associated with the new
table name. (Bug #13920437)
• InnoDB: If the server crashed while dropping an InnoDB temporary table or an index on a temporary
table, further errors could occur during crash recovery, preventing the server from restarting. (Bug
#13913670)
• InnoDB: A FULLTEXT query for an InnoDB table could filter the search terms incorrectly if a term using
the minus operator was followed by another term using the plus operator. (Bug #13907075)
186
MySQL 5.6 Release Notes
• InnoDB: The performance_schema counters for InnoDB RW-locks did not record some cases where
mini-transactions acquired locks. (Bug #13860722)
• InnoDB: Deleting a huge amount of data from InnoDB tables within a short time could cause the
purge operation that removes delete-marked records to stall. This issue could result in unnecessary
disk space use, but does not cause any problems with data integrity. If this issue causes a disk space
shortage, restart the server to work around it. This issue is only likely to occur on 32-bit platforms. (Bug
#13847885)
• InnoDB: A slave server in a replication configuration could exit while creating an InnoDB temporary
table. (Bug #13838761)
• InnoDB: The server could crash when using the SAVEPOINT statement in conjunction with InnoDB
tables containing FULLTEXT indexes. (Bug #13831840)
• InnoDB: With the innodb_force_recovery configuration option set to 2 or greater, a shutdown could
hang after the message:
InnoDB: Waiting for purge thread to be suspended
This issue was introduced during recent changes within the MySQL 5.6 development cycle. (Bug
#13830371)
• InnoDB: Running concurrent bulk inserts on a server with auto_increment_offset=1,
auto_increment_increment greater than 1, and innodb_autoinc_lock_mode=1 could result in
intermittent errors like the following, even with the primary key set to auto_increment and omitted from
the INSERT statement:
Duplicate entry 'value' for key 'PRIMARY'
The workaround was to set auto_increment_offset=1 or innodb_autoinc_lock_mode=0
(“traditional”). (Bug #13817703, Bug #61209)
• InnoDB: The server could halt with an assertion error when DDL and DML operations were run on the
same InnoDB table simultaneously:
InnoDB: Error: a record lock wait happens in a dictionary operation!
This fix stems from the online DDL feature in MySQL 5.6. (Bug #13641926)
• InnoDB: During an ALTER TABLE statement to create a primary key for an InnoDB table, some column
characteristics could be set incorrectly, leading to errors during subsequent queries. The incorrect data
could be the maximum length for a column prefix, or the state of the NOT NULL flag.
In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine. (Bug
#13641275)
• InnoDB: An ALTER TABLE statement for an InnoDB table that dropped one index and create
another could fail with an error code 1280, and displaying the wrong index name in the message. (Bug
#13029445, Bug #62544)
• InnoDB: If the innodb_undo_tablespaces and innodb_undo_logs configuration options were
specified to refer to separate undo tablespaces, and the associated tablespaces did not exist, that error
condition was not being correctly detected during startup. (Bug #13016100)
187
MySQL 5.6 Release Notes
• InnoDB: The error handling and message was improved for attempting to create a foreign key with a
column referencing itself. The message suggested a potential problem with the data dictionary, when no
such problem existed. (Bug #12902967)
• InnoDB: For an InnoDB table with a trigger, under the setting innodb_autoinc_lock_mode=1,
sometimes auto-increment values could be interleaved when inserting into the table from two sessions
concurrently. The sequence of auto-increment values could vary depending on timing, leading to data
inconsistency in systems using replication. (Bug #12752572, Bug #61579)
• InnoDB: An ALTER TABLE with both IGNORE and ADD UNIQUE KEY clauses produced an error if
duplicates were found, rather than removing all duplicate rows after the first one. With this fix, the ALTER
TABLE IGNORE syntax automatically enables the ALGORITHM=COPY clause if the ALTER TABLE
statement creates an index. (Bug #12622150)
• InnoDB: When data was removed from an InnoDB table, newly inserted data might not reuse the freed
disk blocks, leading to an unexpected size increase for the system tablespace or .ibd file (depending
on the setting of innodb_file_per_table. The OPTIMIZE TABLE could compact a .ibd file in
some cases but not others. The freed disk blocks would eventually be reused as additional data was
inserted. (Bug #11766634, Bug #59783)
• InnoDB: The CHECK TABLE statement could fail for a large InnoDB table due to a timeout value of 2
hours. For typical storage devices, the issue could occur for tables that exceeded approximately 200
or 350 GB, depending on I/O speed. The fix relaxes the locking performed on the table being checked,
which makes the timeout less likely. It also makes InnoDB recognize the syntax CHECK TABLE QUICK,
which avoids the possibility of the timeout entirely. (Bug #11758510, Bug #50723)
• InnoDB: Full-text search in InnoDB tried to follow foreign key references without keeping track of which
ones it had already seen. With circular and other complex setups, this could loop forever or a very long
time, leading to the appearance of the query thread hanging. (Bug #64274, Bug #13701973)
• Partitioning: If a partitioned table t1 was created using the ROW_FORMAT option, attempting to perform
ALTER TABLE t1 EXCHANGE PARTITION ... WITH TABLE t2 failed with the error Tables have
different definitions even if the definition for table t2 was identical to that for t1. This occurred
because a check was made for an explicit ROW_FORMAT setting in the table definition, and if this was set,
the operation was rejected.
Now in such cases the row format actually used for each table is checked explicitly and the EXCHANGE
PARTITION operation is permitted to execute if both row formats are the same. (Bug #11894100)
• Partitioning: The PARTITION_COMMENT column of the INFORMATION_SCHEMA.PARTITIONS table
truncated partition comments, displaying only the first 80 characters.
As part of the fix for this issue, the maximum length for a partition comment is now set at 1024
characters, and this width is honored by INFORMATION_SCHEMA.PARTITIONS.PARTITION_COMMENT.
(Bug #11748924, Bug #37728)
• Replication: When a complete global transaction spanned relay logs such that only its GTID appeared
in a given relay log while the body of the transaction (including BEGIN and COMMIT statements)
appeared in the next relay log, the GTID was interpreted incorrectly as belonging to an empty group.
(Bug #14136654)
• Replication: It was possible in some cases when using semisynchronous replication for log rotation to
take place before an ongoing transaction was committed or rolled back. (Bug #14123372)
• Replication: If the relay logs were removed after the server was stopped, without stopping replication
first, the server could not be started correctly. (Bug #14029212, Bug #65152)
188
MySQL 5.6 Release Notes
References: See also: Bug #13971348.
• Replication: The --bootstrap option for mysqld is used by mysql_install_db when it initializes
the system tables. Now, whenever this option is used, GTIDs (see Replication with Global Transaction
Identifiers) and replication are automatically disabled. (Bug #13992602)
• Replication: It was theoretically possible for concurrent execution of more than one instance of SHOW
BINLOG EVENTS to crash the MySQL Server. (Bug #13979418)
• Replication: If errors were encountered while trying to initialize the mysql.slave_master_info or
mysql.slave_relay_log_info tables, the server refused to start. Now in such cases, the warning
message Error while checking replication metadata. This might also happen when
doing a live upgrade from a version that did not make use of the replication
metadata tables is issued to advise the user that this has happened, but the server is permitted to
continue starting. (Bug #13893363)
• Replication: The text for the error ER_AUTO_POSITION_REQUIRES_GTID_MODE_ON referred to
AUTO_POSITION = 1 although this should be MASTER_AUTO_POSITION = 1. The text has been
corrected. (Bug #13868465)
• Replication: A CHANGE MASTER TO statement could alter the effective value of relay_log_purge.
In addition, the relay_log_recovery system variable is now read-only, and can be changed only by
starting the server with --relay-log-recovery. (Bug #13840948)
• Replication: When binlog_rows_query_log_events = 1 and a statement is written to the binary
log using the row-based logging format, the server generates a an additional log event containing
the text of the original statement. If mysqlbinlog is executed on this log using the --verbose -verbose, the original statement is printed. To prevent the statement from being executed in addition to
the row event (which would in effect cause the statement to be excuted twice), it is commented out with
a leading # character.
This was implemented with the assumption that such a statement would consist of a single line, which
meant that a statement covering multiple lines was handled incorrectly, in that only the first line of the
statement actually commented out. Now in such cases, every line of the statement is commented out
with a leading #. (Bug #13799555)
• Replication: Queries that were more than 255 characters in length were truncated when viewed in
the output of SHOW BINLOG EVENTS or mysqlbinlog. This was due to the length of the query being
stored in Rows_query_log_events using a single byte. (Bug #13799489)
• Replication: Replication locks and some of the protocols controlling the use of these locks were not well
implemented or enforced. In particular, this fix improves lock handling for statements such as CHANGE
MASTER TO, SHOW SLAVE STATUS, and FLUSH LOGS. (Bug #13779291)
• Replication: When logging transactions that affected both transactional and nontransactional tables, the
following statements could sometimes be written into the binary log in the wrong order or on the wrong
side of a transaction boundary:
• SET,
• CREATE FUNCTION,
• SHOW BINLOG EVENTS,
• REVOKE ALL PRIVILEGES.
(Bug #13627921)
189
MySQL 5.6 Release Notes
• Replication: Setting binlog_checksum on the master to a value that was unknown on the slave
caused replication to fail. Now in such cases, replication checksums are disabled on the slave and
replication stops with an appropriate error message. (Bug #13553750, Bug #61096)
• Replication: To provide a crash-safe slave, it was previously necessary to change the storage engine
for the slave_master_info, slave_relay_log_info, and slave_worker_info tables from
MyISAM to InnoDB manually, by issuing ALTER TABLE. To simplify the setup of replication using these
slave log tables, they are now created using the InnoDB storage engine. (Bug #13538891)
• Replication: When the slave had been set using CHANGE MASTER TO with the MASTER_DELAY option
equal to any permitted value greater than zero, then stopped using STOP SLAVE, pointed at the current
relay log position (as shown by SHOW SLAVE STATUS), and started again, START SLAVE failed with
the error Could not initialize master info structure. (Bug #12995174)
• Replication: The --relay-log-space-limit option was sometimes ignored.
More specifically, when the SQL thread went to sleep, it allowed the I/O thread to queue additional
events in such a way that the relay log space limit was bypassed, and the number of events in the queue
could grow well past the point where the relay logs needed to be rotated. Now in such cases, the SQL
thread checks to see whether the I/O thread should rotate and provide the SQL thread a chance to purge
the logs (thus freeing space).
Note that, when the SQL thread is in the middle of a transaction, it cannot purge the logs; it can only ask
for more events until the transaction is complete. Once the transaction is finished, the SQL thread can
immediately instruct the I/O thread to rotate. (Bug #12400313, Bug #64503)
References: See also: Bug #13806492.
• Replication: An event whose length exceeded the size of the master dump thread's
max_allowed_packet caused replication to fail. This could occur when updating many large rows and
using row-based replication.
As part of this fix, a new server option --slave-max-allowed-packet is added, which permits
max_allowed_packet to be exceeded by the slave SQL and I/O threads. Now the size of a packet
transmitted from the master to the slave is checked only against this value (available as the value
of the slave_max_allowed_packet server system variable), and not against the value of
max_allowed_packet. (Bug #12400221, Bug #60926)
• Replication: Statements using AUTO_INCREMENT, LAST_INSERT_ID(), RAND(), or user variables
could be applied in the wrong context on the slave when using statement-based replication and
replication filtering server options (see How Servers Evaluate Replication Filtering Rules). (Bug
#11761686, Bug #54201)
References: See also: Bug #11754117, Bug #45670, Bug #11746146, Bug #23894.
• Replication: An INSERT into a table that has a composite primary key that includes an
AUTO_INCREMENT column that is not the first column of this composite key is not safe for statementbased binary logging or replication. Such statements are now marked as unsafe and fail with an error
when using the STATEMENT binary logging format. For more information, see Determination of Safe and
Unsafe Statements in Binary Logging, as well as Replication and AUTO_INCREMENT.
Note
This issue does not affect tables using the InnoDB storage engine, since an
InnoDB table with an AUTO_INCREMENT column requires at least one key
where the auto-increment column is the only or leftmost column.
190
MySQL 5.6 Release Notes
(Bug #11754117, Bug #45670)
References: See also: Bug #11761686, Bug #54201, Bug #11746146, Bug #23894.
• Replication: After upgrading a replication slave to MySQL 5.6.2 or later, enabling the query cache
eventually caused the slave to fail. (Bug #64624, Bug #14005409)
• Microsoft Windows: On Windows, mysqlslap crashed for attempts to connect using shared memory.
(Bug #31173, Bug #11747181, Bug #59107, Bug #11766072)
• Microsoft Windows: For Microsoft Windows, the deprecated MySQL Configuration Wizard is no longer
distributed, and instead the newer MySQL Installer is available and preferred.
• After running ALTER TABLE tbl DISCARD TABLESPACE for an InnoDB table, certain other ALTER
TABLE operations such as renaming the table or rebuilding the primary key could cause a crash. (Bug
#14213568)
• For conditions of the form WHERE p1 AND (p2 OR p3), the optimizer now uses the index merge
access method on (p2,p3) if it is more efficient than a range scan on p1. Previously, index merge was
not considered when a range scan was possible. (Bug #14208922)
• Error messages that should have said "YEAR(2)" said "YEAR(0)" instead. (Bug #14167585)
• For debug builds, INSERT IGNORE INTO ... SELECT that selected more than max_join_size
rows could raise an assertion. (Bug #14145442)
• With logging of the general query log to a table, logging was disabled within a read-only transaction
because write lock acquisition on the log table was blocked. (Bug #14136866)
• The ARCHIVE storage engine could not be built unless the Performance Schema was also built. (Bug
#14116252)
• If a nonexistent page was requested to be loaded into the InnoDB buffer pool by the
innodb_buffer_pool_load_at_startup configuration option, a subsequent shutdown operation
could hang. (Bug #14106082)
• In debug builds, the server failed to check for error status from the storage engine and raised an
assertion. (Bug #14101852)
• In debug builds, warnings occurring during creation of an InnoDB table with ROW_FORMAT=DYNAMIC
and innodb_file_per_table disabled could raise an assertion. (Bug #14101563)
• Derived tables and tables created with CREATE TABLE ... SELECT using the output from single-row
queries with NULL in the first column could change the value to 0. (Bug #14069831)
• Incorrect assessment of column nullability for a subquery result within a trigger could cause “column
cannot be null” errors. (Bug #14069810, Bug #14005353)
• The Performance Schema did not generate consistent digest values for CALL statements. (Bug
#14069132)
• The LooseScan semi-join strategy could fail to remove duplicates from the result set. (Bug #14053325)
• Certain arguments to RPAD() could lead to “uninitialized variable” warnings. (Bug #14039955)
• For debug builds compiled with gcov, tests that used DBUG_SUICIDE lost gcov data. (Bug #14028421)
191
MySQL 5.6 Release Notes
• When the index enforcing a foreign key constraint was dropped while foreign_key_checks=0,
further operations involving the foreign key column could cause a serious error after the
foreign_key_checks option was re-enabled. (Bug #14025221)
• Mishandling of failed internal commits in administrative statements such as ANALYZE TABLE could
cause an assertion to be raised. (Bug #14001091)
• Improper calculation of decimals for TIME values given as arguments to IF() or IFNULL() could cause
a server crash. (Bug #13988413, Bug #14042545)
• Some arguments to MAKETIME() could cause a buffer overflow. (Bug #13982125)
• For debug builds, conversion of a double-precision value to the lldiv_t type could raise an assertion.
(Bug #13976233)
• Mishandling of failure during multiple-table UPDATE IGNORE statements could cause an assertion to be
raised. (Bug #13974815)
• Queries that grouped by an outer BLOB column in a subquery caused a server crash. (Bug #13966809)
• Selecting MIN() or MAX() from a left or right join involving an INFORMATION_SCHEMA table could
cause a server crash. (Bug #13966514)
• Queries containing references to user variables were not written to the general query log with some
rewriting, not as received. (Bug #13958454)
• For debug builds, the optimizer could change the query plan when checking sort order and return
incorrect results. (Bug #13949068)
• An infinite thread loop could develop within Performance Schema, causing the server to become
unresponsive. (Bug #13898343)
• Overhead for Performance Schema table aggregation operations was excessive. (Bug #13862186)
• The version_compile_machine system variable sometimes did not include the value 64 for server
binaries compiled on a 64-bit system. (Bug #13859866)
• With subquery materialization enabled, some queries with a subquery in the HAVING clause caused a
server crash. (Bug #13848789)
• When the InnoDB persistent statistics feature was turned on, an ALTER TABLE statement on an
InnoDB table with delete-marked records could cause a crash (non-debug builds) or assertion error
(debug builds). (Bug #13838962, Bug #13867915)
• In bootstrap mode, the server signal handler thread did not shut down if the server aborted early. (Bug
#13837221)
• Some errors in MySQL 5.6 had different numbers than in MySQL 5.5. (Bug #13833438)
• If KILL QUERY interrupted an INSERT or UPDATE that had the IGNORE modifier, OK was incorrectly
returned to the client rather than an error code. Now an error (“Query execution was interrupted”) is
returned instead. (Bug #13822652)
• If KILL QUERY interrupted a statement during derived table materialization, the server crashed later
trying to read the nonexistent materialized table. (Bug #13820776)
• Incorrect cost calculations for two-table joins could lead to incorrect join order. (Bug #13810048)
References: This issue is a regression of: Bug #26106.
192
MySQL 5.6 Release Notes
• The Performance Schema stored identifiers in digest tables as utf8 without converting them from the
original character set first. (Bug #13809293)
• Incorrect stored program caching could cause statements within a stored program that included a GROUP
BY clause to return different results across multiple program invocations. (Bug #13805127)
• For comparison of a temporal value to and indexed character column, the optimizer could apply the
range access method and thus perform an indexed search that found only literal matches. This is
incorrect because MySQL permits a variety of delimiters in temporal values represented as strings. (Bug
#13803810)
• Several clarifications were made to optimizer trace output. (Bug #13799348)
• viosslfactories did not compile on Oracle Linux 6.0 with CMake options -DWITH_SSL=system and
-DWITH_DEBUG=1. (Bug #13799126)
• In debug builds, a race condition in a signal handler during shutdown caused a server crash. (Bug
#13793813)
• A prepared statement that referenced views and were executed using semi-join transformation could
return different results for different executions. (Bug #13773979)
References: See also: Bug #14641759.
• Outer join queries with ALL could return incorrect results because the optimizer incorrectly rewrote them
to use inner join. (Bug #13735712)
• (a,b) IN (SELECT c,d FROM t1 WHERE ...) could produce incorrect results if t1 had an index
on (c, d) and c or d contained NULL values. (Bug #13731417)
• For open ranges that effectively resulted in a full index scan, the optimizer did not discard the range
predicate as unneeded. (Bug #13731380)
• The range optimizer sometimes did not treat equivalent expressions the same, depending on the order
of the operands. For example, it could treat a <= b and b >= a differently. (Bug #13701206)
• With semi-join optimization enabled, an assertion was raised for queries for which the number of tables
was greater than the search depth. (Bug #13685026)
• Truncating a table partition did not invalidate queries in the query cache that used the table. (Bug
#13485448)
• Setting max_sort_length to small values could cause a server crash. (Bug #13485416)
• A query executed with literal values in the WHERE clause could return results different from the same
query written to select the same literal values from a separate table using a SELECT statement in the
WHERE clause. (Bug #13468414)
• Condition handler code could assume that after handler execution, control would pass up a single level
to the parent, sometimes leading to a server crash. (Bug #13431226)
• If a GROUP_CONCAT() result was calculated using intermediate results (for example, if ORDER BY or
DISTINCT was present), individual intermediate results were each truncated to a maximum of 64K,
even if the group_concat_max_len system variable was set to a larger value. Now the length of any
intermediate result and the final result are controlled by the group_concat_max_len value. (Bug
#13387020)
• Queries with ALL subquery predicates could return incorrect results due to a faulty query transformation.
(Bug #13330886)
193
MySQL 5.6 Release Notes
• Switching between index scans and random scans using the HANDLER interface could result in failure of
the interface to properly reinitialize scans. (Bug #13008220)
• The presence of a file named .empty in the test database prevented that database from being
dropped. (Bug #12845091)
• For queries with ORDER BY COUNT(*) and LIMIT, the optimizer could choose an execution plan that
produced incorrect results. (Bug #12713907)
• For some subqueries that should be executed using a range scan on a nonprimary index and required
use of filesort, only the first execution of the subquery was done as a range scan. All following
executions were done as full table scans, resulting in poor performance. In addition, if index condition
pushdown was used, incorrect results could be returned. (Bug #12667154)
• IPv6 functions such as IS_IPV6() produced Valgrind warnings with arguments that used a multibyte
character set. (Bug #12635232, Bug #14040277)
• Queries that used STRAIGHT_JOIN and were executed using Multi-Range Read optimization could
result in a memory leak. (Bug #12365385)
• Overhead for the Performance Schema was reduced. (Bug #12346211)
• IN subqueries that used a variance or standard deviation aggregate function could return a different
result depending on whether the optimizer_switch materialization flag was enabled.
Note
Those aggregate functions may now return a result with a different number of
decimals from previously.
(Bug #11766758)
• On Windows, initial database creation failed during bootstrapping. (Bug #11766342)
• A regression bug in the optimizer could cause excessive disk usage for UPDATE statements on InnoDB
tables. For tables created with innodb_file_per_table enabled, OPTIMIZE TABLE can be used
to recover excessive space used. For tables created in the InnoDB system tablespace,it is necessary
to perform a dump and restore into a new instance of the system tablespace. (Bug #65745, Bug
#14248833)
• Parse errors that occurred while loading UCA or LDML collation descriptions were not written to the error
log. (Bug #65593, Bug #14197426)
• Incorrect metadata could be produced for columns returned from some views. (Bug #65379, Bug
#14096619)
• If an account had a nonzero MAX_USER_CONNECTIONS value, that value was not always respected.
(Bug #65104, Bug #14003080)
• When an ALTER TABLE operation was performed with an invalid foreign key constraint, the error
reported was ER_CANT_CREATE_TABLE rather than ER_CANNOT_ADD_FOREIGN. (Bug #64617, Bug
#13840553)
• SAVEPOINT statements were incorrectly disallowed within XA transactions. (Bug #64374, Bug
#13737343)
References: See also: Bug #11766752.
194
MySQL 5.6 Release Notes
• The server crashed at shutdown if the slow query log file was a named pipe. (Bug #64345, Bug
#13733221)
• Some Czech error messages contained invalid characters. (Bug #64310, Bug #13726075)
• With lower_case_table_names=2 on systems with case-insensitive file systems such as Windows or
OS X, CREATE TABLE ... LIKE did not preserve lettercase of the destination table name as given in
the statement. (Bug #64211, Bug #13702397)
• File access by the ARCHIVE storage engine was not instrumented and thus not shown in Performance
Schema tables. (Bug #63340, Bug #13417440)
• The Performance Schema incorrectly displayed some backslashes in Windows file names (by doubling
them). (Bug #63339, Bug #13417446)
• An inappropriate mutex was used to protect random number generation, causing contention during
connect operations. (Bug #62282, Bug #12951609)
• mysql_store_result() and mysql_use_result() are not for use with prepared statements and
are not intended to be called following mysql_stmt_execute(), but failed to return an error when
invoked that way in libmysqld. (Bug #62136, Bug #13738989)
References: See also: Bug #47485.
• Under some conditions, the effect of RENAME USER was not recognized until FLUSH PRIVILEGES was
used (which should not be necessary). (Bug #61865, Bug #12766319)
• If the --bind-address option was given a host name value and the host name resolved to more
than one IP address, the server failed to start. For example, with --bind-address=localhost, if
localhost resolved to both 127.0.0.1 and ::1, startup failed. Now the server prefers the IPv4
address in such cases. (Bug #61713, Bug #12762885)
• SHOW TABLES was very slow unless the required information was already in the disk cache. (Bug
#60961, Bug #12427262)
• On Windows, the mysql client crashed when invoked using its full path name. (Bug #60858, Bug
#12402882)
• Sessions could end up deadlocked when executing a combination of SELECT, DROP TABLE, KILL, and
SHOW ENGINE INNODB STATUS. (Bug #60682, Bug #12636001)
• For debug builds, errors occurring during processing of INSERT DELAYED statements could crash the
server. (Bug #60114, Bug #11827404)
• Using CONCAT() to construct a pattern for a LIKE pattern match could result in memory corrupting and
match failure. (Bug #59140, Bug #11766101)
• Due to a race condition, it was possible for two threads to end up with the same query ID for different
queries. (Bug #58785, Bug #11765785)
• For queries with range predicates, the optimizer could miscalculate the number of key parts used,
possibly leading to a server crash. (Bug #58731, Bug #11765737)
• SHOW statements treated stored procedure, stored function, and event names as case sensitive. (Bug
#56224, Bug #11763507)
• mysqlbinlog exited with no error code if file write errors occurred. (Bug #55289, Bug #11762667)
195
MySQL 5.6 Release Notes
• yaSSL rejected valid SSL certificates that OpenSSL accepts. (Bug #54348, Bug #11761822)
• If the server held a global mutex while doing network I/O, client disconnections could be slow. (Bug
#53096, Bug #11760669)
• A multiple-table UPDATE with the IGNORE keyword resulted in an inappropriate and not meaningful Got
error 0 from storage engine message. (Bug #49539, Bug #11757486)
• When dumping the mysql database, mysqldump did not include the general_log and
slow_query_log tables because they cannot be locked. This caused a problem after reloading the
dump file if that file contained a DROP DATABASE statement for the mysql database: The database no
longer contained the log tables and attempts to log to them failed. Now mysqldump includes statements
to re-create the general_log and slow_query_log tables so that they exist after loading the dump
file. Log table contents still are not dumped. (Bug #45740, Bug #11754178)
• When a query was killed, the error code was not always properly propagated up through the server
code. (Bug #43353, Bug #11752226)
• The optimizer could chose a worse execution plan for a condition that used a quoted number compared
to the unquoted number. (Bug #43319, Bug #11752201)
• Queries that used WHERE (col1, col2) IN ((const, const)) were optimized for SELECT, but
not for DELETE or UPDATE. (Bug #43187, Bug #11752097)
• For ALTER TABLE with the IGNORE keyword, IGNORE is now part of the information provided to the
storage engine. It is up to the storage engine whether to use this when choosing between the in-place
or copy algorithm for altering the table. For InnoDB index operations, IGNORE is not used if the index is
unique, so the copy algorithm is used. (Bug #40344, Bug #11750045)
• LEFT JOIN on derived tables was very slow. This is now addressed through the use of subquery
materialization. (Bug #34364, Bug #11747876)
• MySQL was overly agressive in enforcing the NO_ZERO_DATE and NO_ZERO_IN_DATE SQL modes
for default values in column definitions for CREATE TABLE and ALTER TABLE statements. Previously,
default dates that were invalid with those SQL modes enabled produced an error, even when strict
mode was not enabled. Now with NO_ZERO_DATE or NO_ZERO_IN_DATE enabled, invalid default dates
produce a warning if strict SQL mode is not enabled, and an error if strict mode is enabled. (Bug #34280,
Bug #11747847)
• Redundant “Specified key was too long” messages could be produced by index-creation operations.
(Bug #31149, Bug #11747177)
• Code for the storage engine API did not check the return value from the ha_rnd_init(),
ha_index_init(), and index_init() functions. (Bug #26040, Bug #11746399, Bug #54166, Bug
#11761652)
• For table or database names that are longer than 64 characters, the error “Incorrect table name” was
returned rather than “Identifier too long”. (Bug #25168, Bug #11746295)
• During the startup process, mysqld could incorrectly remove the PID file of an already running mysqld.
(Bug #23790, Bug #11746142)
References: See also: Bug #14726272.
• Using ALTER TABLE to add a TIMESTAMP column containing DEFAULT CURRENT_TIMESTAMP in the
definition resulted in a column containing '0000-00-00 00:00:00', not the current timestamp. (Bug
#17392, Bug #11745578)
196
MySQL 5.6 Release Notes
Changes in MySQL 5.6.5 (2012-04-10, Milestone 8)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
Beginning with MySQL 5.6.5, Oracle no longer provides binaries for OS X 10.5. This aligns with Apple no
longer providing updates or support for this platform.
• Data Type Notes
• Replication with GTIDs
• Host Cache Notes
• Optimizer Notes
• Performance Schema Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
Data Type Notes
• Previously, at most one TIMESTAMP column per table could be automatically initialized or updated to the
current date and time. This restriction has been lifted. Any TIMESTAMP column definition can have any
combination of DEFAULT CURRENT_TIMESTAMP and ON UPDATE CURRENT_TIMESTAMP clauses. In
addition, these clauses now can be used with DATETIME column definitions. For more information, see
Automatic Initialization and Updating for TIMESTAMP and DATETIME.
Replication with GTIDs
• Important Change; Replication: This release introduces global transaction identifiers (GTIDs) for
MySQL Replication. A GTID is a unique identifier that is assigned to each transaction as it is committed;
this identifier is unique on the MySQL Server where the transaction originated, as well as across all
MySQL Servers in a given replication setup. Because GTID-based replication depends on tracking
transactions, it cannot be employed with tables that employ a nontransactional storage engine such as
MyISAM; thus, it is currently supported only with InnoDB tables.
Because each transaction is uniquely identified, it is not necessary when using GTIDs to specify
positions in the master's binary log when starting a new slave or failing over to a new master. This
is reflected in the addition of a new MASTER_AUTO_POSITION option for the CHANGE MASTER TO
statement which takes the place of the MASTER_LOG_FILE and MASTER_LOG_POS options when
executing this statement to prepare a MySQL Server to act as a replication slave.
To enable GTIDs on a MySQL Server, the server must be started with the options --gtid-mode=ON
--disable-gtid-unsafe-statements --log-bin --log-slave-updates. These options are
needed whether the server acts as a replication master or as a replication slave; the --gtid-mode and
197
MySQL 5.6 Release Notes
--disable-gtid-unsafe-statements options are new in this release. Once the master and slave
have each been started with these options, it is necessary only to issue a CHANGE MASTER TO ...
MASTER_AUTO_POSITION=1 followed by START SLAVE on the slave to start replication.
A number of new server system variables have also been added for monitoring GTID usage. For more
information about these options and variables, see Global Transaction ID Options and Variables.
As part of these changes, three new mysqlbinlog options—--include-gtids, --exclude-gtids,
and --skip-gtids—have been added for reading binary logs produced when the server participates in
replication with GTIDs.
Important
Due to an issue discovered just prior to release, you cannot import a dump made
using mysqldump from a MySQL 5.5 server to a MySQL 5.6.5 server and then
use mysqlupgrade on the MySQL 5.6.5 server while GTIDs are enabled; doing
so makes it impossible to connect to the server normally following the upgrade.
Instead, you should import the dump and run mysqlupgrade while the MySQL
5.6.5 server is running with --gtid-mode=OFF, then restart it with --gtidmode=ON. (Bug #13833710) (mysqlupgrade can be executed when the server
is running with --gtid-mode set either to OFF, or to ON.)
For additional information about GTIDs and setting up GTID-based replication, see Replication with
Global Transaction Identifiers.
Host Cache Notes
• MySQL now provides more information about the causes of errors that occur when clients connect to the
server, as well as improved access to the host cache, which contains client IP address and host name
information and is used to avoid DNS lookups. These changes have been implemented:
• New Connection_errors_xxx status variables provide information about connection errors that do
not apply to specific client IP addresses.
• The host cache has additional counters to track errors that do apply to specific IP addresses.
• A new host_cache Performance Schema table exposes the contents of the host cache so that it
can be examined using SELECT statements. Access to host cache contents makes it possible to
answer questions such as how many hosts are cached, what kinds of connection errors are occurring
for which hosts, or how close host error counts are to reaching the max_connect_errors system
variable limit. The Performance Schema must be enabled or this table is empty.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate this change into the performance_schema database.
• The host cache size now is configurable using the host_cache_size system variable. Setting the
size to 0 disables the host cache.This is similar to disabling the cache by starting the server with -skip-host-cache, but using host_cache_size is more flexible because it can also be used to
resize, enable, or disable the host cache at runtime, not just at server startup. If you start the server
with --skip-host-cache, the host cache cannot be re-enabled at runtime.
For more information, see DNS Lookup Optimization and the Host Cache, and The host_cache
Table. (Bug #22821, Bug #24906, Bug #45817, Bug #59404, Bug #11746048, Bug #11746269, Bug
#11754244, Bug #11766316)
Optimizer Notes
198
MySQL 5.6 Release Notes
• Reporting of how to sort a result set in EXPLAIN has been improved for some statements. This sorting
decision could be reported incorrectly, causing Using filesort or Using temporary to be reported
when they should not have been or vice versa. This could occur for statements that included index hints,
that had the form SELECT SQL_BIG_RESULT ... GROUP BY, that used SQL_CALC_FOUND_ROWS
with LIMIT, or that used GROUP BY, ORDER BY, and LIMIT. (Bug #11744768, Bug #1560)
• These query optimizer improvements were implemented:
• The EXPLAIN statement now can produce output in JSON format. To select this, use EXPLAIN
FORMAT = JSON explainable_stmt syntax. With FORMAT = JSON, the output includes regular
EXPLAIN information, as well as extended and partition information.
Traditional EXPLAIN output has also changed so that empty columns contain NULL rather the empty
string. In addition, UNION RESULT rows have Using filesort in the Extra column because a
temporary table is used to buffer UNION results.
To work for both Optimizer Trace and JSON-format EXPLAIN output, the end_marker parameter for
the optimizer_trace system variable has been moved to a separate end_markers_in_json
system variable. This is an incompatible change to the optimizer_trace variable. For more
information, see MySQL Internals: Tracing the Optimizer.
• The optimizer tries to find the best query execution plan by beginning with the most promising table
and recursively adding to the plan the most promising of the remaining tables. Partial execution plans
with a higher cost than an already found plan are pruned. The optimizer now attempts to improve
the order in which it adds tables to the plan, resulting in a reduction of the number of partial plans
considered.
Queries that are likely to have improved performance are joins of many tables, where most tables use
eq_ref or ref join types (as indicated by EXPLAIN output).
A new status variable, Last_query_partial_plans, counts the number of iterations the optimizer
makes in execution plan construction for the previous query.
• The optimizer uses semi-join and materialization strategies to optimize subquery execution.
See Optimizing Subqueries with Semi-Join Transformations, and Optimizing Subqueries with
Materialization. In addition, the Batched Key Access (BKA) Join and Block Nested-Loop (BNL) Join
algorithms used for inner join and outer join operations have been extended to support semi-join
operations. For more information, see Block Nested-Loop and Batched Key Access Joins.
Several flags have been added to the optimizer_switch system variable to enable control over
semi-join and subquery materialization strategies. The semijoin flag controls whether semi-joins are
used. If it is set to on, the firstmatch and loosescan flags enable finer control over the permitted
semi-join strategies. The materialization flag controls whether subquery materialization is used. If
semijoin and materialization are both on, semi-joins also use materialization where applicable.
These flags are on by default. See Switchable Optimizations.
• For expressions such as col_name IN(values) that compare a column to a list of values, the
optimizer previously made row estimates using index dives for each value in the list. This becomes
inefficient as the number of values becomes large. The optimizer now can make row estimates for
such expressions using index statistics instead, which is less accurate but quicker for a large number
of values. The point at which the optimizer switches from index dives to index statistics is configurable
using the new eq_range_index_dive_limit system variable. For more information, see Equality
Range Optimization of Many-Valued Comparisons.
Performance Schema Notes
199
MySQL 5.6 Release Notes
• The Performance Schema has these additions:
• The Performance Schema now has a host_cache table that exposes the contents of the host
cache so that it can be examined using SELECT statements. See Host Cache Notes elsewhere in this
changelog.
• The Performance Schema now maintains statement digest information. This normalizes and groups
statements with the same “signature” and permits questions to be answered about the types of
statements the server is executing and how often they occur.
• A statement_digest consumer in the setup_consumers table controls whether the
Performance Schema maintains digest information.
• The statement event tables (events_statements_current, events_statements_history,
and events_statements_history_long) have DIGEST and DIGEST_TEXT columns that
contain digest MD5 values and the corresponding normalized statement text strings.
• A events_statements_summary_by_digest table provides aggregated statement digest
information.
For more information, see The host_cache Table, Performance Schema Statement Event Tables, and
Statement Summary Tables.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the performance_schema database.
Security Notes
• Passwords stored in the older hash format used before MySQL 4.1 are less secure than passwords
that use the native password hashing method and should be avoided. Pre-4.1 passwords and the
mysql_old_password authentication plugin are now deprecated. To prevent connections using
accounts that have pre-4.1 password hashes, the secure_auth system variable is now enabled by
default. (To permit connections for accounts that have such password hashes, start the server with -secure_auth=0.) (Bug #13586336)
• MySQL client programs now issue a warning if a password is given on the command line that this can be
insecure.
Functionality Added or Changed
• Incompatible Change: The obsolete OPTION modifier for the SET statement has been removed.
• InnoDB: --ignore-builtin-innodb is now ignored if used. (Bug #13586262)
• OS X; Microsoft Windows: A new CMake option, MYSQL_PROJECT_NAME, can be set on Windows or
OS X to be used in the project name. (Bug #13551687)
• Microsoft Windows: A new server option, --slow-start-timeout, controls the Windows service
control manager's service start timeout. The value is the maximum number of milliseconds that the
service control manager waits before trying to kill the MySQL service during startup. The default value is
15000 (15 seconds). If the MySQL service takes too long to start, you may need to increase this value. A
value of 0 means there is no timeout. (Bug #45546, Bug #11754011)
• The MySQL-shared-compat RPM package enables users of Red Hat-provided mysql-*-5.1 RPM
packages to migrate to Oracle-provided MySQL-*-5.5 packages. MySQL-shared-compat now
replaces the Red Hat mysql-libs package by replacing libmysqlclient.so files of the latter
package, thus satisfying dependencies of other packages on mysql-libs. This change affects only
200
MySQL 5.6 Release Notes
users of Red Hat (or Red Hat-compatible) RPM packages. Nothing is different for users of Oracle RPM
packages. (Bug #13867506)
• Temporary tables for INFORMATION_SCHEMA queries now use dynamic MyISAM row format if they
contain sufficiently large VARCHAR columns, resulting in space savings. (Bug #13627632)
• As of MySQL 5.5.3, the LOW_PRIORITY modifier for LOCK TABLES ... LOW_PRIORITY WRITE has
no effect. This modifier is now deprecated. Its use should be avoided and now produces a warning. Use
LOCK TABLES ... WRITE instead. (Bug #13586314)
• If the log_queries_not_using_indexes system variable is enabled, slow queries that do not use
indexes are written to the slow query log. In this case, it is now possible to put a logging rate limit on
these queries by setting the new log_throttle_queries_not_using_indexes system variable,
so that the slow query log does not grow too quickly. By default, this variable is 0, which means there
is no limit. Positive values impose a per-minute limit on logging of queries that do not use indexes. The
first such query opens a 60-second window within which the server logs queries up to the given limit,
then suppresses additional queries. If there are suppressed queries when the window ends, the server
logs a summary that indicates how many there were and the aggregate time spent in them. The next 60second window begins when the server logs the next query that does not use indexes. (Bug #55323,
Bug #11762697)
• Several subquery performance issues were resolved through the implementation of semi-join subquery
optimization strategies. See Optimizing Subqueries with Semi-Join Transformations. (Bug #47914, Bug
#11756048, Bug #58660, Bug #11765671, Bug #10815, Bug #11745162, Bug #9021, Bug #13519134,
Bug #48763, Bug #11756798, Bug #25130, Bug #11746289)
• The mysql client now supports an --init-command=str option. The option value is an SQL
statement to execute after connecting to the server. If auto-reconnect is enabled, the statement is
executed again after reconnection occurs. (Bug #45634, Bug #11754087)
• New utf8_general_mysql500_ci and ucs2_general_mysql500_ci collations have been
added that preserve the behavior of utf8_general_ci and ucs2_general_ci from versions of
MySQL previous to 5.1.24. Bug #27877 corrected an error in the original collations but introduced an
incompatibility for columns that contain German 'ß' LATIN SMALL LETTER SHARP S. (As a result
of the fix, that character compares equal to characters with which it previously compared different.) A
symptom of the problem after upgrading to MySQL 5.1.24 or newer from a version older than 5.1.24 is
that CHECK TABLE produces this error:
Table upgrade required.
Please do "REPAIR TABLE `t`" or dump/reload to fix it!
Unfortunately, REPAIR TABLE could not fix the problem. The new collations permit older tables created
before MySQL 5.1.24 to be upgraded to current versions of MySQL.
To convert an affected table after a binary upgrade that leaves the table files in place, alter the table to
use the new collation. Suppose that the table t1 contains one or more problematic utf8 columns. To
convert the table at the table level, use a statement like this:
ALTER TABLE t1
CONVERT TO CHARACTER SET utf8 COLLATE utf8_general_mysql500_ci;
To apply the change on a column-specific basis, use a statement like this (be sure to repeat the column
definition as originally specified except for the COLLATE clause):
ALTER TABLE t1
201
MySQL 5.6 Release Notes
MODIFY c1 CHAR(N) CHARACTER SET utf8 COLLATE utf8_general_mysql500_ci;
To upgrade the table using a dump and reload procedure, dump the table using mysqldump, modify the
CREATE TABLE statement in the dump file to use the new collation, and reload the table.
After making the appropriate changes, CHECK TABLE should report no error. (Bug #43593, Bug
#11752408)
References: See also: Bug #27877.
• The SET TRANSACTION and START TRANSACTION statements now support READ WRITE and READ
ONLY modifiers to set the transaction access mode for tables used in transactions. The default mode is
read/write, which is the same mode as previously. Read/write mode now may be specified explicitly with
the READ WRITE modifier. Using READ ONLY prohibits table changes and may enable storage engines
to make performance improvements that are possible when changes are not permitted.
In addition, the new --transaction-read-only option and tx_read_only system variable permit
the default transaction access mode to be set at server startup and runtime.
For more information, see SET TRANSACTION Syntax, and START TRANSACTION, COMMIT, and
ROLLBACK Syntax.
• MySQL distributions no longer include the GPL readline input-editing library. This results in simpler
maintenance and support, and simplifies licensing considerations.
Bugs Fixed
• Incompatible Change; Replication: CHANGE MASTER TO statements were written into the error log
using quoted numeric values, although the syntax for this statement does not allow such option values to
be quoted. This meant that such statements could not be copied from the error log and re-run verbatim.
Now CHANGE MASTER TO statements are written to the error log without the extraneous quotation
marks, and so are syntactically correct as logged.
• Incompatible Change: A change in MySQL 5.6.3 caused LAST_DAY() to be more strict and reject
incomplete dates with a day part of zero. For this function, a nonzero day part is not necessary, so the
change has been reverted. (Bug #13458237)
• Important Change; InnoDB: When a row grew in size due to an UPDATE operation, other (nonupdated) columns could be moved to off-page storage so that information about the row still fit within
the constraints of the InnoDB page size. The pointer to the new allocated off-page data was not set
up until the pages were allocated and written, potentially leading to lost data if the system crashed
while the column was being moved out of the page. The problem was more common with tables using
ROW_FORMAT=DYNAMIC or ROW_FORMAT=COMPRESSED along with the Barracuda file format, particularly
with the innodb_file_per_table setting enabled, because page allocation operations are more
common as the .ibd tablespace files are extended. Still, the problem could occur with any combination
of InnoDB version, file format, and row format.
A related issue was that during such an UPDATE operation, or an INSERT operation that reused a deletemarked record, other transactions could see invalid data for the affected column, regardless of isolation
level.
The fix corrects the order of operations for moving the column data off the original page and replacing it
with a pointer. Now if a crash occurs at the precise moment when the column data is being transferred,
the transfer will not be re-run during crash recovery.
In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine. (Bug
#13721257, Bug #12612184, Bug #12704861)
202
MySQL 5.6 Release Notes
• Important Change; Partitioning: The query cache did not always function correctly with partitioned
tables in a transactional context. For this reason, the query cache is now disabled for any queries using
partitioned tables, and such queries can no longer be cached. For more information, see Restrictions
and Limitations on Partitioning. (Bug #11761296, Bug #53775)
• Important Change; Replication: The CHANGE MASTER TO statement was not checked for invalid
characters in values for options such as MASTER_HOST and MASTER_USER. In addition, when the
server was restarted, a value containing certain characters was trimmed, causing the loss of its original
value. Now such values are validated, and in cases where the value contains invalid characters,
including linefeed (\n or 0x0A) characters, the statement fails with an error (ER_MASTER_INFO). (Bug
#11758581, Bug #50801)
• Important Change; Replication: Moving the binary log file, relay log file, or both files to a new location,
then restarting the server with a new value for --log-bin, --relay-log, or both, caused the server to
abort on start. This was because the entries in the index file overrode the new location. In addition, paths
were calculated relative to datadir (rather than to the --log-bin or --relay-log values).
The fix for this problem means that, when the server reads an entry from the index file, it now checks
whether the entry contains a relative path. If it does, the relative part of the path is replaced with the
absolute path set using the --log-bin or --relay-log option. An absolute path remains unchanged;
in such a case, the index must be edited manually to enable the new path or paths to be used. (Bug
#11745230, Bug #12133)
• Performance; InnoDB: The optimizer now takes into account InnoDB page sizes other than 16KB,
which can be configured with the innodb_page_size option when creating a MySQL instance. This
change improves the estimates of I/O costs for queries on systems with non-default InnoDB page sizes.
(Bug #13623078)
• Performance; InnoDB: Memory allocation for InnoDB tables was reorganized to reduce the memory
overhead for large numbers of tables or partitions, avoiding situations where the “resident set size” could
grow regardless of FLUSH TABLES statements. The problem was most evident for tables with large row
size. Some of the memory that was formerly allocated for every open table is now allocated only when
the table is modified for the first time. (Bug #11764622, Bug #57480)
• Performance: Temporary MyISAM tables (unlike normal MyISAM tables) did not use the dynamic row
format when they contained VARCHAR columns, resulting in larger temporary files (and more file I/O) than
necessary. Dynamic row format now is used, which results in smaller tables that are faster to process.
(Bug #13350136, Bug #78840, Bug #22023218)
• InnoDB: An erroneous assertion could occur, in debug builds only, when creating an index on a column
containing zero-length values (that is, ''). (Bug #13654923)
• InnoDB: A DDL operation such as ALTER TABLE ... ADD COLUMN could stall, eventually timing out
with an Error 1005: Can't create table message referring to fil_rename_tablespace.
(Bug #13636122, Bug #62100, Bug #63553)
• InnoDB: If InnoDB was started with innodb_force_recovery set to a value of 3 or 4, and there are
transactions to roll back, normal shutdown would hang waiting for those transactions to complete. Now
the shutdown happens immediately, without rolling back any transactions, because non-zero values for
innodb_force_recovery are only appropriate for troubleshooting and diagnostic purposes. (Bug
#13628420)
• InnoDB: The MySQL server could hang in some cases if the configuration option
innodb_use_native_aio was turned off. (Bug #13619598)
• InnoDB: A Valgrind error was fixed in the function os_aio_init(). (Bug #13612811)
203
MySQL 5.6 Release Notes
• InnoDB: The configuration option innodb_sort_buf_size was renamed to
innodb_sort_buffer_size for consistency. This work area is used while creating an InnoDB index.
(Bug #13610358)
• InnoDB: The server could crash when creating an InnoDB temporary table under Linux, if the $TMPDIR
setting points to a tmpfs filesystem and innodb_use_native_aio is enabled, as it is by default in
MySQL 5.5.4 and higher. The entry in the error log looked like:
101123 2:10:59 InnoDB: Operating system error number 22 in a file operation.
InnoDB: Error number 22 means 'Invalid argument'.
The crash occurred because asynchronous I/O is not supported on tmpfs in some Linux kernel versions.
The workaround was to turn off the innodb_use_native_aio setting or use a different temporary
directory. The fix causes InnoDB to turn off the innodb_use_native_aio setting automatically if
it detects that the temporary file directory does not support asynchronous I/O. (Bug #13593888, Bug
#11765450, Bug #58421)
• InnoDB: During startup, the status variable Innodb_buffer_pool_dump_status could be empty for
a brief time before being initialized to the correct value not started. (Bug #13513676)
• InnoDB: Valgrind errors when referencing the internal function buf_LRU_scan_and_free_block()
were fixed. (Bug #13491704)
• InnoDB: The MySQL error log could contain messages like:
InnoDB: Ignoring strange row from mysql.innodb_index_stats WHERE ...
The fix makes the contents of the innodb_index_stats and innodb_table_stats tables casesensitive, to properly distinguish the statistics for tables whose names differ only in letter case. Other
cases were fixed where the wrong name could be selected for an index while retrieving persistent
statistics. (Bug #13432465)
• InnoDB: References to C preprocessor symbols and macros HAVE_purify,
UNIV_INIT_MEM_TO_ZERO, and UNIV_SET_MEM_TO_ZERO were removed from the InnoDB source
code. They were only used in debug builds instrumented for Valgrind. They are replaced by calls to the
UNIV_MEM_INVALID() macro. (Bug #13418934)
• InnoDB: The MySQL server could halt with an assertion error:
InnoDB: Failing assertion: page_get_n_recs(page) > 1
Subsequent restarts could fail with the same error. The error occurred during a purge operation
involving the InnoDB change buffer. The workaround was to set the configuration option
innodb_change_buffering=inserts. (Bug #13413535, Bug #61104)
• InnoDB: A discrepancy could arise between the number of available InnoDB undo logs and the number
of undo logs that were currently active. Now the innodb_undo_logs system variable reports the
number of active undo logs, and the new Innodb_available_undo_logs status variable reports the
total number of undo logs. (Bug #13255225)
• InnoDB: When doing a live downgrade from MySQL 5.6.4 or later, with innodb_page_size set to a
value other than 16384, now the earlier MySQL version reports that the page size is incompatible with
the older version, rather than crashing or displaying a “corruption” error. (Bug #13116225)
• InnoDB: Certain CREATE TABLE statements could fail for InnoDB child tables containing
foreign key definitions. This problem affected Windows systems only, with the setting
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MySQL 5.6 Release Notes
lower_case_table_names=0. It was a regression from MySQL bug #55222. (Bug #13083023, Bug
#60229)
• InnoDB: If the server crashed during a TRUNCATE TABLE or CREATE INDEX statement for an InnoDB
table, or a DROP DATABASE statement for a database containing InnoDB tables, an index could be
corrupted, causing an error message when accessing the table after restart:
InnoDB: Error: trying to load index index_name for table table_name
InnoDB: but the index tree has been freed!
In MySQL 5.1, this fix applies to the InnoDB Plugin, but not the built-in InnoDB storage engine. (Bug
#12861864, Bug #11766019)
• InnoDB: A DDL operation for an InnoDB table could cause a busy MySQL server to halt with an
assertion error:
InnoDB: Failing assertion: trx->error_state == DB_SUCCESS
The error occurred if the DDL operation was run while all 1023 undo slots were in use by concurrent
transactions. This error was less likely to occur in MySQL 5.5 and 5.6, because raising the number of
InnoDB undo slots increased the number of simultaneous transactions (corresponding to the number of
undo slots) from 1K to 128K. (Bug #12739098, Bug #62401)
• InnoDB: InnoDB persistent statistics gave less accurate estimates for date columns than for columns
of other data types. The fix changes the way cardinality is estimated for nonunique keys, and avoids
situations where identical values could be counted twice if they occurred on different index pages. (Bug
#12429443)
• InnoDB: The innodb_max_purge_lag variable controls how to delay DML operations when purge
operations are lagging. Previously, if an old consistent read view was detected, DML operations would
not be delayed even though the purge lag exceeded the innodb_max_purge_lag setting.
Additionally, if the innodb_max_purge_lag setting was used, situations could arise in which the
DML delay time would continue to increase but not be applied right away due to the presence an old
consistent read view. This could result in a lengthy DML delay when the accumulated DML delay time is
eventually applied.
This fix caps the DML delay at a maximum value, removes the consistent read check, and revises the
DML delay calculation. (Bug #12407434, Bug #60776)
• InnoDB: With 1024 concurrent InnoDB transactions running concurrently and the
innodb_file_per_table setting enabled, a CREATE TABLE operation for an InnoDB table could fail.
The .ibd file from the failed CREATE TABLE was left behind, preventing the table from being created
later, after the load had dropped.
The fix adds error handling to delete the erroneous .ibd file. This error was less likely to occur in
MySQL 5.5 and 5.6, because raising the number of InnoDB undo slots increased the number of
simultaneous transactions needed to trigger the bug, from 1K to 128K. (Bug #12400341)
• InnoDB: Improved the accuracy of persistent InnoDB statistics for large tables. The estimate of distinct
records could be inaccurate if the index tree was more than 3 levels deep. (Bug #12316365)
• InnoDB: Shutdown could hang with messages like this in the log:
Waiting for purge thread
to be suspended
205
MySQL 5.6 Release Notes
After 1 hour, the shutdown times out and mysqld quits. This problem is most likely to occur with a high
value for innodb_purge_threads. (Bug #11765863, Bug #58868, Bug #60939)
• InnoDB: When DROP TABLE failed due to all undo slots being in use, the error returned was Unknown
table '...' rather than the expected Too many active concurrent transactions. (Bug
#11764724, Bug #57586)
References: See also: Bug #11764668, Bug #57529.
• InnoDB: Server startup could produce an error for temporary tables using the InnoDB storage engine, if
the path in the $TMPDIR variable ended with a / character. The error log would look like:
120202 19:21:26 InnoDB: Operating system error number 2 in a file operation.
InnoDB: The error means the system cannot find the path specified.
InnoDB: If you are installing InnoDB, remember that you must create
InnoDB: directories yourself, InnoDB does not create them.
120202 19:21:26 InnoDB: Error: trying to open a table, but could not
InnoDB: open the tablespace file './t/#sql7750_1_0.ibd'!
InnoDB: Have you moved InnoDB .ibd files around without using the
InnoDB: commands DISCARD TABLESPACE and IMPORT TABLESPACE?
InnoDB: It is also possible that this is a temporary table #sql...,
InnoDB: and MySQL removed the .ibd file for this.
The workaround for the problem was to create a similar temporary table again, copy its .frm file to
tmpdir under the name mentioned in the error message (for example, #sql123.frm) and restart
mysqld with tmpdir set to its normal value without a trailing slash, for example /var/tmp. On
startup, MySQL would see the .frm file and issue DROP TABLE for the orphaned temporary table. (Bug
#11754376, Bug #45976)
• Partitioning: When creating a view from a SELECT statement that used explicit partition selection, the
partition selection portion of the query was ignored. (Bug #13559657)
• Partitioning: Adding a partition to an already existing LIST-partitioned table did not work correctly if
the number of items in the new partition was greater than 16. This could happen when trying to add
a partition using an ALTER TABLE ... ADD PARTITION statement, or an ALTER TABLE ...
REORGANIZE PARTITION statement.
This 16-item limit was not apparent when using either CREATE TABLE ... PARTITION BY LIST or
ALTER TABLE ... PARTITION BY LIST. (Bug #13029508, Bug #62505)
• Partitioning: A function internal to the code for finding matching subpartitions represented an unsigned
number as signed, with the result that matching subpartitions were sometimes missed in results of
queries. (Bug #12725206, Bug #61765)
References: See also: Bug #20257.
• Partitioning: An ALTER TABLE ... ADD PARTITION statement subsequent to ALTER TABLE ...
REORGANIZE PARTITION failed on a table partitioned by HASH or KEY. (Bug #11764110, Bug #56909)
• Replication: Executing mysqlbinlog with the --start-position=N option, where N was equal
either to 0 or to a value greater than the length of the dump file, caused it to crash.
This issue was introduced in MySQL 5.5.18 by the fix for Bug #32228 and Bug #11747416. (Bug
#13593869, Bug #64035)
References: This issue is a regression of: Bug #32228, Bug #11747416.
206
MySQL 5.6 Release Notes
• Replication: When starting the server, replication repositories were checked even when the --serverid was equal to 0 (the default), in spite of the fact that a valid nonzero value for --server-id must be
supplied for a server that acts as either a master or a slave in MySQL replication.
This could cause problems when trying to perform a live upgrade from MySQL 5.5, although it was
possible to work around the issue by starting the server with --skip-slave-start (in addition to any
other required options).
To avoid this problem, replication repositories are now checked only when the server is started with -server-id using a nonzero value. (Bug #13427444, Bug #13504821)
• Replication: Formerly, the default value shown for the Port column in the output of SHOW SLAVE
HOSTS was 3306 whether the port had been set incorrectly or not set at all. Now, when the slave port is
not set, the actual port used by the slave is shown. This change also affects the default shown for the -report-port server option. (Bug #13333431)
• Replication: A race condition could occur when running multiple instances of mysqld on a single
machine, when more than slave thread was started at the same time, and each such thread tried to use
the same temporary file concurrently. (Bug #12844302, Bug #62055)
• Replication: It was possible on replication slaves where FEDERATED tables were in use to get
timeouts on long-running operations, such as Error 1160 Got an error writing communication
packets. The FEDERATED tables did not need to be replicated for the issue to occur. (Bug #11758931,
Bug #51196)
References: See also: Bug #12896628, Bug #61790.
• Replication: Statements that wrote to tables with AUTO_INCREMENT columns based on an unordered
SELECT from another table could lead to the master and the slave going out of sync, as the order in
which the rows are retrieved from the table may differ between them. Such statements include any
INSERT ... SELECT, REPLACE ... SELECT, or CREATE TABLE ... SELECT statement. Such
statements are now marked as unsafe for statement-based replication, which causes the execution of
one to throw a warning, and forces the statement to be logged using the row-based format if the logging
format is MIXED. (Bug #11758263, Bug #50440)
• Replication: On Windows replication slave hosts, STOP SLAVE took an excessive length of time to
complete when the master was down. (Bug #11752315, Bug #43460)
• Replication: mysqlbinlog --database=dbname included all SET INSERT_ID=n assignments from
the binary log in its output, even if database dbname was never referenced in the binary log. This was
due to the fact that COMMIT statements were not associated with any database in the binary log. Now in
such cases, the current database is tracked so that only those SET INSERT_ID assignments that are
made in the context of changes to tables in database dbname are actually printed in the mysqlbinlog
output. (Bug #11746146, Bug #23894)
References: See also: Bug #23890, Bug #46998, Bug #11761686, Bug #54201, Bug #11754117, Bug
#45670.
• Microsoft Windows: On Windows, rebuilds in a source distribution failed to create the initial database
due to insufficient cleanup from the previous run or failure to find the proper server executable. (Bug
#13431251)
• Microsoft Windows: On Windows, the server incorrectly constructed the full path name of the plugin
binary for INSTALL PLUGIN and CREATE FUNCTION ... SONAME. (Bug #45549, Bug #11754014)
207
MySQL 5.6 Release Notes
• mysqldump tried to execute SET statements as SET OPTION, which failed when used against 5.6 or
higher servers because the deprecated OPTION keyword has been removed from SET syntax. (Bug
#13813473)
• The optimizer did not perform constant propagation for views, so a query containing views resulted in a
less efficient execution plan than the corresponding query using only base tables. (Bug #13783777)
• A memory leak could occur for queries containing a subquery that used GROUP BY on an outer column.
(Bug #13724099)
• After using an ALTER TABLE statement to change the KEY_BLOCK_SIZE property for an InnoDB table,
for example when switching from an uncompressed to a compressed table, subsequent server restarts
could fail with a message like:
InnoDB: Error: data file path/ibdata2 uses page size 1024,
InnoDB: but the only supported page size in this release is=16384
This issue is a regression introduced in MySQL 5.5.20. (Bug #13698765, Bug #64160)
• In debug builds, a Debug Sync timeout warning was treated as an error, causing an assertion to be
raised. (Bug #13688248)
• _mi_print_key() iterated one time too many when there was a NULL bit, resulting in Valgrind
warnings. (Bug #13686970)
• Pushing down to InnoDB an index condition that called a stored function resulted in a server crash. This
kind of condition is no longer pushed down. (Bug #13655397)
• A SELECT from a subquery that returned an empty result could itself fail to return an empty result as
expected. (Bug #13651009, Bug #13650418)
• For debug builds, negative values with a zero integer part and nonzero fractional part (such as -0.1111)
were not detected, so the negative fractional part was later cast to a large unsigned number and raised
an assertion. (Bug #13616434)
• If during server startup a signal such as SIGHUP was caught prior to full server initialization, the server
could crash. This was due to a race condition between the signal handler thread and the main thread
performing server initialization. To prevent this from happening, signal processing is now suspended
until full initialization of all server components has been completed successfully. (Bug #13608371, Bug
#62311)
• The shared version of libmysqlclient did not export these functions for linking by client programs:
get_tty_password(), handle_options(), my_print_help(). (Bug #13604121)
• An aggregated expression of type MIN() or MAX() should return NULL but could instead return the
empty set if the query was implicitly grouped and there was no HAVING clause that evaluates to FALSE.
(Bug #13599013)
• Left join queries could be incorrectly converted to inner joins and return erroneous result sets. (Bug
#13595212)
• Date-handling code could raise an assertion attempting to calculate the number of seconds since the
epoch. (Bug #13545236)
• For queries that used a join type of ref_or_null, the optimizer could skip the filesort operation and
sort the results incorrectly. (Bug #13531865)
208
MySQL 5.6 Release Notes
• For some queries, a filesort operation was done even when the result contained only a single row and
needed no sorting. (Bug #13529048)
• The optimizer could return an incorrect select limit in some cases when a query included no explicit
LIMIT clause. (Bug #13528826)
• In some cases, the optimizer failed to use a covering index when that was possible and read data rows
instead. (Bug #13514959)
• SELECT statements failed for the EXAMPLE storage engine. (Bug #13511529)
References: This issue is a regression of: Bug #11746275.
• The Performance Schema instrumentation for stages did not fully honor the ENABLED column in the
schema.setup_instruments table. (Bug #13509513)
• Converting a string ending with a decimal point (such as '1.') to a floating-point number raised a data
truncation warning. (Bug #13500371)
• Use of an uninitialized TABLE_SHARE member could cause a server crash. (Bug #13489996)
• Some outer joins that used views as inner tables did not evaluate conditions correctly. (Bug #13464334)
• A query that used an index on a CHAR column referenced in a BETWEEN clause could return invalid
results. (Bug #13463488, Bug #63437)
• Expressions that compared a BIGINT column with any non-integer constant were performed using
integers rather than decimal or float values, with the result that the constant could be truncated. This
could lead to any such comparison that used <, >, <=, >=, =, !=/<>, IN, or BETWEEN yielding false
positive or negative results. (Bug #13463415, Bug #11758543, Bug #63502, Bug #50756)
• An application linked against libmysqld could crash in debug mode with a stack smashing
detected error if it tried to connect without specifying the user name. (Bug #13460909)
• Instantiating a derived table for a query with an empty result caused a server crash. (Bug #13457552)
• When the optimizer performed conversion of DECIMAL values while evaluating range conditions, it could
produce incorrect results. (Bug #13453382)
• Implicitly grouped queries with a const table and no matching rows could return incorrect results. (Bug
#13430588)
• For debug builds, enabling optimizer_trace could cause an assertion to be raised. (Bug #13430443)
• Enabling index condition pushdown could cause performance degradation. (Bug #13430436)
• When a fixed-width row was inserted into a MyISAM temporary table, the entire content of the record
buffer was written to the table, including any trailing space contained in VARCHAR columns, the issue
being that this trailing space could be uninitialized. This problem has been resolved by insuring that only
the bytes actually used to store the VARCHAR (and none extra) are copied and inserted in such cases.
(Bug #13389854, Bug #79028, Bug #22123583)
• Fractional seconds parts were lost for certain UNION ALL queries. (Bug #13375823)
• When merging ranges that effectively resulted in a full index scan, the optimizer did not discard the
range predicate as unneeded. (Bug #13354910)
• When executing EXPLAIN, it was assumed that only the default multi-range read implementation could
produce an ordered result; this meant that when a query on a table that used a storage engine providing
209
MySQL 5.6 Release Notes
its own sorted MRR, it was ignored, so that EXPLAIN failed to report Using MRR even when a multirange read was used. (Bug #13330645)
• Some multiple-table updates could update a row twice. (Bug #13095459)
• Performance Schema idle event timings were not normalized to the same units as wait timings. (Bug
#13018537)
• In MySQL 5.6.3, a number of status variables were changed to longlong types so that they would
roll over much later. However, the format string used by mysqladmin status to print Queries per
second values did not reflect this, causing such values to be misreported. (Bug #12990746)
References: See also: Bug #42698. This issue is a regression of: Bug #11751727.
• For debug builds, two assertions could be raised erroneously for UPDATE statements. (Bug #12912171)
• When the result of a stored function returning a non-integer type was evaluated for NULL, an incorrect
type warning (Warning 1292 Truncated incorrect INTEGER value) is generated, although such
a test for NULL should work with any type. This could cause stored routines not handling the warning
correctly to fail.
The issue could be worked around by wrapping the result in an expression, using a function such as
CONCAT(). (Bug #12872824, Bug #62125)
• When running mysqldump with both the --single-transaction and --flush-logs options, the
flushing of the log performed an implicit COMMIT (see Statements That Cause an Implicit Commit),
causing more than one transaction to be used and thus breaking consistency. (Bug #12809202, Bug
#61854)
• A query that used an aggregate function such as MAX() or MIN() of an index with NOT BETWEEN in the
WHERE clause could fail to match rows, thus returning an invalid result. (Bug #12773464, Bug #61925)
• With ONLY_FULL_GROUP_BY SQL mode enabled, columns that were not aggregated in the select list or
named in a GROUP BY were incorrectly permitted in ORDER BY. (Bug #12626418)
• Mishandling of NO_BACKSLASH_ESCAPES SQL mode within stored procedures on slave servers could
cause replication failures. (Bug #12601974)
• Passing a user variable as an argument to GROUP_CONCAT() could cause a server exit if the variable
value changed during query execution. (Bug #12408412)
• LOAD INDEX INTO CACHE could cause a server exit if the index cache was too small. (Bug
#12361113)
• With ONLY_FULL_GROUP_BY SQL mode enabled, a query that uses GROUP BY on a column derived
from a subquery in the FROM clause failed with a column isn't in GROUP BY error, if the query was
in a view. (Bug #11923239)
• Attempting to execute ALTER TABLE on a temporary MERGE table having an underlying temporary table
rendered the MERGE table unusable, unless the ALTER TABLE specified a new list of underlying tables.
(Bug #11764786, Bug #57657)
• It was possible in the event of successive failures for mysqld_safe to restart quickly enough to
consume excessive amounts of CPU. Now, on systems that support the sleep and date system
utilities, mysqld_safe checks to see whether it has restarted more than 5 times in the current second,
and if so, waits 1 second before attempting another restart. (Bug #11761530, Bug #54035)
• A HAVING clause in a query using MIN() or MAX() was sometimes ignored. (Bug #11760517, Bug
#52935)
210
MySQL 5.6 Release Notes
References: See also: Bug #11758970, Bug #51242, Bug #11759718, Bug #52051.
• When used with the --xml option, mysqldump --routines failed to dump any stored routines,
triggers, or events. (Bug #11760384, Bug #52792)
• If an attempt to initiate a statement failed, the issue could not be reported to the client because it was not
prepared to receive any error messages prior to the execution of any statement. Since the user could not
execute any queries, they were simply disconnected without providing a clear error.
After the fix for this issue, the client is prepared for an error as soon as it attempts to initiate a statement,
so that the error can be reported prior to disconnecting the user. (Bug #11755281, Bug #47032)
• Previously, .OLD files were not included among the files deleted by DROP DATABASE. Files with this
extension are now also deleted by the statement. (Bug #11751736, Bug #42708)
• A prepared statement using a view whose definition changed between preparation and execution
continued to use the old definition, which could cause the prepared statement to return incorrect results.
(Bug #11748352, Bug #36002)
• Some debugging information was written to the buffer after a flush, resulting in the information not
appearing until the next flush. (Bug #64048, Bug #13608112)
• Locale information for FORMAT() function instances was lost in view definitions. (Bug #63020, Bug
#13344643)
• mysqlhotcopy failed for databases containing views. (Bug #62472, Bug #13006947, Bug #12992993)
• The VIO description string was initialized even for connections where it was unneeded. (Bug #62285,
Bug #12951586)
• On Windows, pasting multiple-line input including a CRLF terminator on the last line into the mysql
client resulted in the first character of the last line being changed, resulting in erroneous statements.
Handling of newlines in pasted input was also incorrect. (Bug #60901, Bug #12589167, Bug #64104,
Bug #13639107)
• The contents of the shared and shared-compat RPM packages had been changed in versions
5.5.6 and 5.6.1 to avoid the overlap which they traditionally had (and still have in MySQL 5.0 and 5.1).
However, the RPM meta information had not been changed in accordance, and so RPM still assumed a
conflict between shared and shared-compat RPM packages. This has been fixed. (Bug #60855, Bug
#12368215)
References: See also: Bug #56150.
• The result of SUBSTRING_INDEX() could be missing characters when used as an argument to
conversion functions such as LOWER(). (Bug #60166, Bug #11829861)
• UPDATE IGNORE returned an incorrect count for number of rows updated when there were duplicate-key
conflicts in a multiple-table update. (Bug #59715, Bug #11766576)
• The optimizer mishandled STRAIGHT_JOIN used with nested joins; for example, by not evaluating
tables in the specified order. (Bug #59487, Bug #11766384, Bug #43368, Bug #11752239, Bug #60080,
Bug #11766858)
• A subquery involved in a comparison requiring a character set conversion caused an error that resulted
in a server crash. (Bug #59185, Bug #11766143)
• The embedded server crashed when argc = 0. (Bug #57931, Bug #12561297)
211
MySQL 5.6 Release Notes
• If tables were locked by LOCK TABLES ... READ in another session, SET GLOBAL read_only = 1
failed to complete. (Bug #57612, Bug #11764747)
• Invalid memory reads could occur when cmp_item_sort_string::store_value() tried to refer to
a temporary value that could be changed or deleted by other functions. (Bug #57510, Bug #11764651)
• Assigning the result of a subquery to a user variable raised an assertion when the outer query included
DISTINCT and GROUP BY. (Bug #57196, Bug #11764371)
• For comparisons containing out-of-range constants, the optimizer permitted warnings to leak through to
the client, even though it accounted for the range issue internally. (Bug #56962, Bug #11764155)
• A confusing CREATE TABLE error message was improved. (Bug #54963, Bug #11762377)
• The handle_segfault() signal-handler code in mysqld could itself crash due to calling unsafe
functions. (Bug #54082, Bug #11761576)
• Using myisamchk with the sort recover method to repair a table having fixed-width row format could
cause the row pointer size to be reduced, effectively resulting in a smaller maximum data file size. (Bug
#48848, Bug #11756869)
• Enabling myisam_use_mmap could cause the server to crash. (Bug #48726, Bug #11756764)
• For MEMORY tables, a scan of a HASH index on a VARCHAR column could fail to find some rows if the
index was on a prefix of the column. (Bug #47704, Bug #11755870)
• myisam_sort_buffer_size could not be set larger than 4GB on 64-bit systems. (Bug #45702, Bug
#11754145)
• The stored routine cache was subject to a small memory leak that over time or with many routines being
used could result in out-of-memory errors.
The fix for this issue also introduces a new global server system variable stored_program_cache
which can be used for controlling the size of the stored routine cache. (Bug #44585, Bug #11753187)
• Under some circumstances, the result of SUBSTRING_INDEX() incorrectly depended on the contents of
the previous row. (Bug #42404, Bug #11751514)
• Setting an event to DISABLED status and with the ON COMPLETION NOT PRESERVE attribute caused it
to be dropped at the next server restart. (Bug #37666, Bug #11748899)
• Due to improper locking, concurrent inserts into an ARCHIVE table at the same time as repair and check
operations on the table resulted in table corruption. (Bug #37280, Bug #11748748)
• Stored functions could produce an error message that referred to ORDER BY even though the offending
statement within the function had no such clause. (Bug #35410, Bug #11748187)
Changes in MySQL 5.6.4 (2011-12-20, Milestone 7)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
212
MySQL 5.6 Release Notes
• Condition Handler Changes
• Fractional Seconds Handling
• InnoDB Notes
• Optimizer Notes
• Performance Schema Notes
• Functionality Added or Changed
• Bugs Fixed
Condition Handler Changes
• Incompatible Change: MySQL now supports the GET DIAGNOSTICS statement. GET DIAGNOSTICS
provides applications a standardized way to obtain information from the diagnostics area, such as
whether the previous SQL statement produced an exception and what it was. For more information, see
GET DIAGNOSTICS Syntax.
In addition several deficiencies in condition handler processing rules were corrected so that MySQL
behavior is more like standard SQL:
• Block scope is used in determining which handler to select. Previously, a stored program was treated
as having a single scope for handler selection.
• Condition precedence is more accurately resolved.
• Diagnostics area clearing has changed. Bug #55843 caused handled conditions to be cleared from
the diagnostics area before activating the handler. This made condition information unavailable within
the handler. Now condition information is available to the handler, which can inspect it with the GET
DIAGNOSTICS statement. The condition information is cleared when the handler exits, if it has not
already been cleared during handler execution.
• Previously, handlers were activated as soon as a condition occurred. Now they are not activated until
the statement in which the condition occurred finishes execution, at which point the most appropriate
handler is chosen. This can make a difference for statements that raise multiple conditions, if a
condition raised later during statement execution has higher precedence than an earlier condition and
there are handlers in the same scope for both conditions. Previously, the handler for the first condition
raised would be chosen, even if it had a lower precedence than other handlers. Now the handler
for the condition with highest precedence is chosen, even if it is not the first condition raised by the
statement.
• Issues that caused server crashes resulting from incorrect handler call stack processing were fixed.
The work just described involved several condition-handler bug fixes:
• The RETURN statement did not clear the diagnostics area as it should have. Now the diagnostics area
is cleared before executing RETURN. This prevents a condition in a nested function call from incorrectly
propagating to an outer scope. It also means there is no way to return an SQL warning from a stored
function. This change is not backward compatible, but the resulting behavior is more like standard
SQL.
• When an SQL HANDLER was activated, the handled condition was immediately removed from the
diagnostics area. Consequently, any SQL diagnostic statement executed in the handler was unable to
examine the condition that triggered the handler.
213
MySQL 5.6 Release Notes
• If multiple handlers existed at the same level within a stored program, the wrong one could be chosen.
• If an error occurred in a context where different handlers were present at different levels of nesting, an
outer handler could be chosen rather than the innermost one.
For more information, see Scope Rules for Handlers. (Bug #12951117, Bug #38806, Bug #11749343,
Bug #55852, Bug #11763171, Bug #61392, Bug #12652873, Bug #11660, Bug #11745196, Bug #48637,
Bug #11756690)
Fractional Seconds Handling
• Incompatible Change: MySQL now permits fractional seconds for TIME, DATETIME, and TIMESTAMP
values, with up to microseconds (6 digits) precision. To define a column that includes a fractional
seconds part, use the syntax type_name(fsp), where type_name is TIME, DATETIME, or
TIMESTAMP, and fsp is the fractional seconds precision. For example:
CREATE TABLE t1 (t TIME(3), dt DATETIME(6));
The fsp value, if given, must be in the range 0 to 6. A value of 0 signifies that there is no fractional part.
If omitted, the default precision is 0. (This differs from the standard SQL default of 6, for compatibility
with previous MySQL versions.)
The following items summarize the implications of this change. See also Fractional Seconds in Time
Values.
• For TIME, DATETIME, and TIMESTAMP columns, the encoding and storage requirements in new
tables differ from such columns in tables created previously because these types now include a
fractional seconds part. This can affect the output of statements that depend on the row format, such
as CHECKSUM TABLE.
• Due to these changes in encoding and storage requirements for MySQL's DATETIME and TIMESTAMP
types, importing pre-MySQL 5.6.4 InnoDB tables using ALTER TABLE ... IMPORT TABLESPACE
that contain DATETIME and TIMESTAMP types into MySQL 5.6.4 (or later) requires a workaround
procedure which is described in the “Server Changes” section of Changes Affecting Upgrades to
MySQL 5.6 .
• Syntax for temporal literals now produces temporal values: DATE 'str', TIME 'str', and
TIMESTAMP 'str', and the ODBC-syntax equivalents. The resulting value includes a trailing
fractional seconds part if specified. Previously, the temporal type keyword was ignored and these
constructs produced the string value. See Standard SQL and ODBC Date and Time Literals
• Functions that take temporal arguments accept values with fractional seconds. Return values from
temporal functions include fractional seconds as appropriate.
• Three INFORMATION_SCHEMA tables, COLUMNS, PARAMETERS, and ROUTINES, now have a
DATETIME_PRECISION column. Its value is the fractional seconds precision for TIME, DATETIME,
and TIMESTAMP columns, and NULL for other data types.
• The C API accommodates fractional seconds as follows:
• In the MYSQL_FIELD column metadata structure, the decimals member indicates the fractional
seconds precision for TIME, DATETIME, and TIMESTAMP columns. Clients can determine whether
a result set temporal column has a fractional seconds part by checking for a nonzero decimals
value in the corresponding MYSQL_FIELD structure. Previously, the decimals member indicated
the precision for numeric columns and was zero otherwise.
214
MySQL 5.6 Release Notes
• In the MYSQL_TIME structure used for the binary protocol, the second_part member indicates the
microseconds part for TIME, DATETIME, and TIMESTAMP columns. Previously, the second_part
member was unused.
In some cases, previously accepted syntax may produce different results. The following items indicate
where existing code may need to be changed to avoid problems:
• Some expressions produce results that differ from previous results. Examples: The timestamp
system variable returns a value that includes a microseconds fractional part rather than an integer
value. Functions that return a result that includes the current time (such as CURTIME(), SYSDATE(),
or UTC_TIMESTAMP()) interpret an argument as an fsp value and the return value includes a
fractional seconds part of that many digits. Previously, these functions permitted an argument but
ignored it.
• TIME values are converted to DATETIME by adding the time to the current date. (This means that
the date part of the result differs from the current date if the time value is outside the range from
'00:00:00' to '23:59:59'.) Previously, conversion of TIME values to DATETIME was unreliable.
See Conversion Between Date and Time Types.
• TIMESTAMP(N) was permitted in old MySQL versions, but N was a display width rather than fractional
seconds precision. Support for this behavior was removed in MySQL 5.5.3, so applications that are
reasonably up to date should not be subject to this issue. Otherwise, code must be rewritten.
Note
There may be problems replicating from a master server that understands
fractional seconds to an older slave that does not:
• For CREATE TABLE statements containing columns that have an fsp value
greater than 0, replication will fail due to parser errors.
• Statements that use temporal data types with an fsp value of 0 will work for
with statement-based logging but not row-based logging. In the latter case, the
data types have binary formats and type codes on the master that differ from
those on the slave.
• Some expression results will differ on master and slave. For example,
expressions that involve the timestamp system variable or functions that
return the current time have different results, as described earlier.
(Bug #8523, Bug #11745064)
InnoDB Notes
• MySQL now supports FULLTEXT indexes for InnoDB tables. The core syntax is very similar to
the FULLTEXT capability from earlier releases, with the CREATE TABLE and CREATE INDEX
statements, and MATCH() ... AGAINST() clause in the SELECT statement. The new @ operator
allows proximity searches for terms that are near each other in the document. The detailed search
processing is controlled by a new set of configuration options: innodb_ft_enable_stopword,
innodb_ft_server_stopword_table, innodb_ft_user_stopword_table,
innodb_ft_cache_size, innodb_ft_min_token_size, and innodb_ft_max_token_size.
You can monitor the workings of the InnoDB full-text search system by querying new
INFORMATION_SCHEMA tables: innodb_ft_default_stopword, innodb_ft_index_table,
innodb_ft_index_cache, innodb_ft_config, innodb_ft_deleted, and
innodb_ft_being_deleted.
215
MySQL 5.6 Release Notes
Optimizer Notes
• These query optimizer improvements were implemented:
• The optimizer detects and optimizes away these useless query parts within IN/ALL/SOME/EXISTS
subqueries:
• DISTINCT
• GROUP BY, if there is no HAVING clause and no aggregate functions
• ORDER BY, which has no effect because LIMIT is not supported in these subqueries
Performance Schema Notes
• The Performance Schema has these additions:
• The Performance Schema now permits instrument and consumer configuration at server
startup, which previously was possible only at runtime using UPDATE statements for the
setup_instruments and setup_consumers tables. This change was made because configuration
at runtime is too late to disable instruments that have already been initialized during server startup. For
example, the wait/sync/mutex/sql/LOCK_open mutex is initialized once during server startup, so
attempts to disable the corresponding instrument at runtime have no effect.
To control an instrument at server startup, use an option of this form:
--performance-schema-instrument='instrument_name=value'
Here, instrument_name is an instrument name such as wait/sync/mutex/sql/LOCK_open,
and value is one of these values:
• off, false, or 0: Disable the instrument
• on, true, or 1: Enable and time the instrument
• counted: Enable and count (rather than time) the instrument
Each --performance-schema-instrument option can specify only one instrument name, but
multiple instances of the option can be given to configure multiple instruments. In addition, patterns
are permitted in instrument names to configure instruments that match the pattern. To configure all
condition synchronization instruments as enabled and counted, use this option:
--performance-schema-instrument='wait/synch/cond/%=counted'
To disable all instruments, use this option:
--performance-schema-instrument='%=off'
Longer instrument name strings take precedence over shorter pattern names, regardless of order. For
information about specifying patterns to select instruments, see Naming Instruments or Consumers for
Filtering Operations.
An unrecognized instrument name is ignored. It is possible that a plugin installed later may create the
instrument, at which time the name is recognized and configured.
To control a consumer at server startup, use an option of this form:
216
MySQL 5.6 Release Notes
--performance-schema-consumer_consumer_name=value
Here, consumer_name is a consumer name such as events_waits_history, and value is one of
these values:
• off, false, or 0: Do not collect events for the consumer
• on, true, or 1: Collect events for the consumer
For example, to enable the events_waits_history consumer, use this option:
--performance-schema-consumer-events-waits-history=on
The permitted consumer names can be found by examining the setup_consumers table. Patterns
are not permitted.
Along with the preceding changes to permit configuration at server startup, the default instrument and
consumer configuration has changed. Previously, all instruments and consumers were enabled by
default. Now, instruments are disabled except the statement, I/O, and idle instruments. Consumers
are disabled except the global, thread, and current-statement consumers. These changes produce a
default configuration with a low overhead.
• Tables that have an EVENT_ID column now also have an END_EVENT_ID column to support
determination of nested event relationships:
• events_waits_current, events_waits_history, events_waits_history_long
• events_stages_current, events_stages_history, events_stages_history_long
• events_statements_current, events_statements_history,
events_statements_history_long
As before, EVENT_ID is populated with the thread current event counter when an event starts. In
addition, END_EVENT_ID is NULL until the event ends, at which point it is set to the new thread current
event counter. This permits the relationship “event B is included in event A” to be determined using the
following expression, without having to follow each inclusion relationship using NESTING_EVENT_ID:
A.EVENT_ID <= B.EVENT_ID AND B.END_EVENT_ID <= A.END_EVENT_ID
• The Performance Schema aggregates file I/O operations in two places, the
events_waits_summary_xxx tables and the file_summary_xxx tables. It was
possible to join the events_waits_summary_global_by_event_name table to the
file_summary_by_event_name by using the EVENT_NAME column. However, it was not possible to
do the same with the events_waits_summary_by_instance and file_summary_by_instance
tables because the former uses OBJECT_INSTANCE_BEGIN as the instance identifier and the latter
uses FILE_NAME. This means that it was possible to obtain both file I/O latency and usage per file, but
not to correctly correlate latency to usage when there was more than one form of file (such as multiple
redo logs, table files, and so forth).
To address this issue, the file_summary_by_instance table now has an
OBJECT_INSTANCE_BEGIN column. In addition, both file_summary_by_instance and
file_summary_by_event_name have additional aggregation columns (such as timer wait
217
MySQL 5.6 Release Notes
information), which in many cases makes it possible to obtain the desired summary information
without need for a join at all.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the performance_schema database.
For more information, see MySQL Performance Schema.
Functionality Added or Changed
• Performance; InnoDB: New optimizations apply to read-only InnoDB transactions. See Optimizing
InnoDB Read-Only Transactions for details. The new optimizations make autocommit more applicable
to InnoDB queries than before, as a way to signal that a transaction is read-only because it is a singlestatement SELECT.
• Performance; InnoDB: You can now set the InnoDB page size for uncompressed tables to 8KB
or 4KB, as an alternative to the default 16KB. This setting is controlled by the innodb_page_size
configuration option. You specify the size when creating the MySQL instance. All InnoDB tablespaces
within an instance share the same page size. Smaller page sizes can help to avoid redundant or
inefficient I/O for certain combinations of workload and storage devices, particularly SSD devices with
small block sizes.
• Replication: Previously, replication slaves could connect to the master server only through master
accounts that use native authentication. Now replication slaves can also connect through master
accounts that use nonnative authentication if the required client-side plugin is installed on the slave side
in the directory named by the slave plugin_dir system variable. (Bug #12897501)
• The optimizer trace capability now tracks temporary tables created by the server during statement
execution. (Bug #13400713)
• Performance of metadata locking operations on Windows XP systems was improved by instituting a
cache for metadata lock objects. This permits the server to avoid expensive operations for creation and
destruction of synchronization objects on XP. A new system variable, metadata_locks_cache_size,
permits control over the size of the cache. The default size is 1024. (Bug #12695572)
• Upgrading from an Advanced GPL RPM package to an Advanced RPM package did not work. Now
on Linux it is possible to use rpm -U to replace any installed MySQL product by any other of the same
release family. It is not necessary to remove the old produce with rpm -e first. (Bug #11886309)
• The make_win_bin_dist script is no longer used and has been removed from MySQL distributions
and the manual. (Bug #58241)
• MEMORY table creation time is now available in the CREATE_TIME column of the
INFORMATION_SCHEMA.TABLES table and the Create_time column of SHOW TABLE STATUS output.
(Bug #51655, Bug #11759349)
• Previously, MySQL servers from 5.1 and up refused to open ARCHIVE tables created in 5.0 because
opening them caused a server crash. The server now can open 5.0 ARCHIVE tables, and REPAIR
TABLE updates them to the format used in 5.6. However, the recommended upgrade procedure is still
to dump 5.0 ARCHIVE tables before upgrading and reload them after upgrading. (Bug #48633, Bug
#11756687)
• Error messages that referred only to an error code now also include the corresponding error description.
(Bug #48348, Bug #11756433)
• The MySQL code base was changed to permit use of the C++ Standard Library and to enable
exceptions and runtime type information (RTTI). This change has the following implications:
218
MySQL 5.6 Release Notes
• Libraries and executables depend on some C++ standard library. On Linux, this has not been the case
previously. On Solaris, the default dependency has changed from the default library to libstlport,
which is now included with binary distributions for users whose system does not have it.
• The -fno-rtti and -fno-exceptions options are no longer used to build plugins, such as storage
engines. Users who write their own plugins should omit these options if they were using tem.
• C++ users who compile from source should set CXX to a C++ compiler rather than a C compiler. For
example, use g++ rather than gcc. This includes the server as well as client programs.
• mysql_config now has a --cxxflags option. This is like the --cflags option, but produces flags
appropriate for a C++ compiler rather than a C compiler.
• User-defined functions can be written in C++ using standard library features.
Bugs Fixed
• Security Enhancement; Replication: The START SLAVE statement now accepts USER and PASSWORD
options. By default, MySQL native authentication is used, and the user name and password are stored
in the master.info repository. This behavior can be overridden by additionally specifying the name
(DEFAULT_AUTH) and location (PLUGIN_DIR) of an authentication plugin when issuing START SLAVE. .
As part of this change, warnings are now issued in the following cases:
1. If START SLAVE USER="..." PASSWORD="..." or CHANGE MASTER TO
MASTER_USER="..." MASTER_PASSWORD="..." is executed using an unencrypted connection,
the warning message Sending passwords in plain text without SSL/TLS is
extremely insecure is generated (ER_INSECURE_PLAIN_TEXT).
2. If the user name and password are stored in or read from the master.info repository in the course
of executing CHANGE MASTER TO, a warning message is printed out to the error log: Storing
MySQL user name or password information in the master.info repository is
not secure and is therefore not recommended (ER_INSECURE_CHANGE_MASTER).
Note
The text of a running START SLAVE statement, including values for USER and
PASSWORD, can be seen in the output of a concurrent SHOW PROCESSLIST
statement. The complete text of a CHANGE MASTER TO statement is also visible
to SHOW PROCESSLIST.
See also Pluggable Authentication. (Bug #13083642)
• Incompatible Change; Replication: The statements in the following list are now marked as unsafe for
statement-based replication. This is due to the fact that each of these statements depends on the results
of a SELECT statement whose order cannot always be determined. When using STATEMENT logging
mode, a warning is issued in the binary log for any of these statements; when using MIXED logging
mode, the statement is logged using the row-based format.
• INSERT ... SELECT ... ON DUPLICATE KEY UPDATE
• REPLACE ... SELECT
• CREATE TABLE ... IGNORE SELECT
• CREATE TABLE ... REPLACE SELECT
219
MySQL 5.6 Release Notes
• INSERT IGNORE ... SELECT
• UPDATE IGNORE
When upgrading, you should note the use of these statements in your applications, keeping in mind that
a statement that inserts or replaces rows obtained from a SELECT can take up many times as much
space in the binary log when logged using row-based format than when only the statement itself is
logged. Depending on the number and size of the rows selected and inserted (or replaced) by any such
statements, the difference in size of the binary log after the logging of these statements is switched from
statement-based to row-based can potentially be several orders of magnitude. See Advantages and
Disadvantages of Statement-Based and Row-Based Replication. (Bug #11758262, Bug #50439)
• Incompatible Change: Previously, “Aborted connection” errors were written to the error log based on
the session value of log_warnings, which permitted users with minimal privileges to cause many
messages to be written to the log unless restricted by the MAX_CONNECTIONS_PER_HOUR resource
limit. Now this logging is based on the global log_warnings variable. There are no remaining uses of
the session log_warnings variable, so it has been removed and the variable now has only a global
value. (Bug #53466, Bug #11761014)
• Important Change; InnoDB: If an ALTER TABLE statement failed for an InnoDB table due to an error
code from an underlying file-renaming system call, InnoDB could lose track of the .ibd file for the table.
This issue only occurred when the innodb_file_per_table configuration option was enabled, and
when the low-level error persisted through thousands of retry attempts. In MySQL 5.1, this issue applied
to the InnoDB Plugin but not the built-in InnoDB storage engine.
For example, if you encounter an error like the following:
mysql> ALTER TABLE sb2 ADD COLUMN d2 INT;
ERROR 1025 (HY000): Error on rename of './sbtest/#sql-1eb9_1' to
'./sbtest/sb2' (errno: -1)
you might be able to access the #sql* table by copying a .frm file from a table with an identical
schema. The table name to use for the .frm filewould be `sbtest.#mysql50##sql-1eb9_1` in the
preceding example. (Bug #12884631, Bug #62146)
• Important Change; Replication: Setting an empty user in a CHANGE MASTER TO statement caused
an invalid internal result and is no longer permitted. Trying to use MASTER_USER='' or setting
MASTER_PASSWORD while leaving MASTER_USER unset causes the statement to fail with an error. (Bug
#13427949)
• Performance; InnoDB: The process of deallocating the InnoDB Adaptive Hash Index was made faster,
during shutdown or when turning off the AHI with the statement:
SET GLOBAL innodb_adaptive_hash_index=OFF;
(Bug #13006367, Bug #62487)
• Performance; InnoDB: This fix improves the performance of instrumentation code for InnoDB buffer
pool operations. (Bug #12950803, Bug #62294)
• Performance; InnoDB: This fix improved the efficiency and concurrency of freeing pages in the InnoDB
buffer pool when performing a DROP TABLE for an InnoDB table when the innodb_file_per_table
option is enabled.
220
MySQL 5.6 Release Notes
This change is most noticeable for systems with large buffer pools. During the drop operation, one
traversal of the buffer pool memory structure is changed from the LRU list (the entire buffer pool) to the
flush list (a much smaller structure). The LRU scanning is reduced, but not entirely eliminated. The buffer
pool mutex is also released periodically, so that if the drop operation takes significant time, other threads
can proceed concurrently. (Bug #11759044, Bug #51325)
• InnoDB: An internal deadlock could occur within InnoDB, on a server doing a substantial amount of
change buffering for DML operations, particularly DELETE statements. (Bug #13340047)
• InnoDB: Fixed a compilation problem that affected the InnoDB source code with gcc 4.6.1. The
affected InnoDB source file was btr/btr0cur.c. (Bug #13116045)
• InnoDB: Querying the INFORMATION_SCHEMA.INNODB_SYS_TABLESTATS table could cause the
server to halt with an assertion error, in debug builds only. (Bug #12960058)
• InnoDB: Valgrind errors when building with the settings innodb_checksum_algorithm=innodb and
innodb_checksum_algorithm=crc32 were fixed. (Bug #12939557)
• InnoDB: Unused functions were removed from the internal InnoDB code related to mini-transactions, to
clarify the logic. (Bug #12626794, Bug #61240)
• InnoDB: Lookups using secondary indexes could give incorrect matches under a specific set of
conditions. The conditions involve an index defined on a column prefix, for a BLOB or other long column
stored outside the index page, with a table using the Barracuda file format. (Bug #12601439, Bug
#12543666)
• InnoDB: An UPDATE statement for an InnoDB table could hang. The issue affects tables using the
Barracuda file format and having multiple indexes on column prefixes. The size of an undo log record
could exceed the page size, even though the total size of the column prefixes was less than the
page size (usually 16KB). In MySQL 5.5 and higher, this error is now reported using the new code
ER_UNDO_RECORD_TOO_BIG. In MySQL 5.1 with the InnoDB Plugin, this error is reported using the
existing code ER_TOO_BIG_ROWSIZE. (Bug #12547647)
• InnoDB: This fix corrects cases where the MySQL server could hang or abort with a long semaphore
wait message. (This is a different issue than when these symptoms occurred during a CHECK TABLE
statement.) (Bug #11766591, Bug #59733)
• InnoDB: Issuing INSERT...ON DUPLICATE KEY statements for InnoDB tables from concurrent
threads could cause a deadlock, particularly with the INSERT...ON DUPLICATE KEY UPDATE form.
The problem could also be triggered by issuing multiple INSERT IGNORE statements. The fix avoids
deadlocks caused by the same row being accessed by more than one transaction. Deadlocks could
still occur when multiple rows are inserted and updated simultaneously by different transactions in
inconsistent order; those types of deadlocks require the standard error handling on the application side,
of re-trying the transaction. (Bug #11759688, Bug #52020, Bug #12842206)
• Partitioning: CHECKSUM TABLE returned 0 for a partitioned table unless the statement was used with
the EXTENDED option. (Bug #11933226, Bug #60681)
• Partitioning: Error 1214 (ER_TABLE_CANT_HANDLE_FT), given when trying to use a FULLTEXT
index with a partitioned table, displayed the misleading text The used table type doesn't
support FULLTEXT indexes was misleading and has been replaced with Error 1752
(ER_FULLTEXT_NOT_SUPPORTED_WITH_PARTITIONING) which shows the more accurate FULLTEXT
index is not supported for partitioned tables. (Bug #11763825, Bug #56590)
• Partitioning: Using ALTER TABLE to remove partitioning from a valid MyISAM table could corrupt it.
(Bug #52599, Bug #11760213)
221
MySQL 5.6 Release Notes
• Replication: The value set for the slave_parallel_workers system variable (or the corresponding
--slave-parallel-workers server option) was not always honored correctly; in such cases a
random value was used. (Bug #13334470)
• Replication: Execution of LOAD DATA on a MyISAM table having an after-insert trigger which wrote into
an InnoDB table caused multi-threaded statement-based replication to abort with error 1742 (Cannot
execute the current event group in the parallel mode). (Bug #12982188)
• Replication: Several warnings and informational messages were revised for typographic errors and
clarity. (Bug #12947248, Bug #12978113)
• Replication: When a statement containing a large number of rows to be applied on a slave table that
does not contain a primary key, a considerable amount of time can be needed to find and change all the
rows that are to be changed. The current fix helps diagnose this issue by printing a message to the error
log if the execution time for a given statement replicated using row-based replication takes more than 60
seconds. log_warnings must be greater than 1 for this message to be printed to the error log. (Bug
#11760927, Bug #53375)
• Replication: mysqlbinlog --hexdump printed the last row of the hex dump incorrectly, in two ways:
1. If the length of the last row was eight bytes, the end of the previous row was copied to the end of the
last row, padding the last row to full length.
2. If the length of the last row was less than sixteen bytes, its textual representation was not aligned
with that of previous rows.
(Bug #11747887, Bug #34386)
• Replication: A replication master could send damaged events to slaves after the binary log disk on the
master became full. To correct this issue, only complete events are now pushed by the master dump
thread to the slave I/O thread. In addition, the error text that the master sends to the slave when an
incomplete event is found now states that the incomplete event may have been caused by running out
of disk space on the master, and provides coordinates of the first and the last event bytes read. (Bug
#11747416, Bug #32228)
References: See also: Bug #64035, Bug #13593869.
• Replication: --replicate-rewrite-db=from_name->to_name did not work correctly when the
name of the source database (from_name) consisted of only a single character. (Bug #34332, Bug
#11747866)
• An incorrect InnoDB assertion could cause the server to halt. This issue only affected debug builds.
The assertion referenced the source file btr0pcur.ic and the variable cursor->pos_state. (Bug
#13358468)
• A derived table with more than 64 columns caused a server crash. (Bug #13354889)
• With InnoDB change buffering enabled and innodb_page_size set to an 8K or 4K page size, an
UPDATE statement could fail if a column being updated contained a value longer than 1/8th of the page
size. (Bug #13336585)
• Writes to the slow log involved a call to thd->current_utime() even if no log entries ended up being
written, unnecessarily reducing performance. (Bug #13326965)
• Rounding DBL_MAX returned DBL_MAX, not 'inf'. (Bug #13261955)
• For materialized temporary tables, a missing key length check could cause incorrect query results. (Bug
#13261277)
222
MySQL 5.6 Release Notes
• Access privileges were checked for each stored program instruction, even if the instruction used no
tables, resulting in reduced performance. (Bug #13251277)
• The error message for ER_EVENT_CANNOT_ALTER_IN_THE_PAST was incorrect. (Bug #13247871)
• During the table-opening process, memory was allocated and later freed that was needed view loading,
even for statements that did not use views. These unnecessary allocation and free operations are no
longer done. (Bug #13116518)
• Subqueries with OUTER JOIN could return incorrect results if the subquery referred to a column from
another SELECT. (Bug #13068506)
• Writes to MyISAM temporary tables could include uninitialized data, which could contain sensitive
information. Now only bytes containing initialized data are copied, which also improves performance.
(Bug #12997905)
• The Performance Schema nested some network I/O events within the wrong statement. (Bug
#12981100)
• mysql_plugin mishandled the --plugin-ini, --mysqld, and --my-print-defaults options
under some circumstances. (Bug #12968815)
• mysql_plugin returned the wrong error code from failed server bootstrap execution. (Bug #12968567)
• Internal conversion of zero to binary and back could yield a result with incorrect precision. (Bug
#12911710)
• Valgrind warnings generated by filesort operations were fixed. (Bug #12856915)
• An IN-to-EXISTS subquery transformation could yield incorrect results if the outer value list contained
NULL. (Bug #12838171)
• With index condition pushdown enabled, STRAIGHT_JOIN queries could produce incorrect results. (Bug
#12822678, Bug #12724899)
• The result of ROUND() was incorrect for certain numbers. (Bug #12744991)
• A warning resulting from use of SPACE() referred to REPEAT() in the warning message. (Bug
#12735829)
• IN and EXISTS subqueries with DISTINCT and ORDER BY could return incorrect results. (Bug
#12709738)
• A memory leak occurred due to failure to clean up after QUICK_INDEX_MERGE_SELECT/Unique. (Bug
#12694872, Bug #14542543)
• Several improvements were made to the libedit library bundled with MySQL distributions, and that is
available for all platforms that MySQL supports except Windows.
• Navigation keys did not work for UTF-8 input.
• Word navigation and delete operations did not work for UTF-8 input with Cyrillic characters.
• Nonlatin characters were corrupted in overwrite mode for UTF-8 input.
• Long queries caused the statement history file to become corrupted.
• The Alt key caused history operations to fail.
(Bug #12605400, Bug #12613725, Bug #12618092, Bug #12624155, Bug #12617651, Bug #12605388)
223
MySQL 5.6 Release Notes
• SELECT SQL_BUFFER_RESULT query results included too many rows if a GROUP BY clause was
optimized away. (Bug #12578908)
• decimal_round() could cause a server exit when processing long numeric strings. (Bug #12563865)
• mysqldump --all-databases did not dump the replication log tables. (They could be dumped only by
naming them explicitly when invoking mysqldump, and using the --master-data option.)
As a result of the fix for this problem, it is now possible to execute statements requiring read locks on the
replication log tables at any time, while any statements requiring a write lock on either or both of these
tables are disallowed whenever replication is in progress. For more information, see Replication Relay
and Status Logs. (Bug #12402875, Bug #60902)
• The client-server protocol now has the client send authentication data as lengthencoded strings so that data longer than 256 bytes can be sent. This is done using the
CLIENT_PLUGIN_AUTH_LENENC_CLIENT_DATA client capability. (Bug #11878962)
• mysqld_safe did not properly check for an already running instance of mysqld. (Bug #11878394)
• SUM(DISTINCT) incorrectly converted DATE, DATETIME, TIME, and TIMESTAMP arguments to YEAR.
(Bug #73543, Bug #19427648)
• If index condition pushdown access was chosen and then abandoned, some variables were not cleared,
leading to incorrect query results. (Bug #62533)
• The CMake configuration checks did not properly test whether the C compiler supports the inline
keyword. (Bug #61708, Bug #12711108)
• For a lower_case_table_names value of 1 or 2 and a database having a mixed-case name, calling
a stored function using a fully qualified name including the database name failed. (Bug #60347, Bug
#11840395)
• mysql_upgrade did not upgrade the system tables or create the mysql_upgrade_info file when run
with the --write-binlog or --skip-write-binlog option. (Bug #60223, Bug #11827359)
• A multiple-table UPDATE statement required the UPDATE privilege on a view which was only read if the
view was processed using the merge algorithm. (Bug #59957, Bug #11766767)
• When a join operation contained a view, the optimizer sometimes failed to associate the view's WHERE
clause with the first table or view in a join when it was possible to do so, resulting in a less efficient
query. (Bug #59696, Bug #11766559)
• An assertion was raised when selecting from a view that selects from a view that used a user-defined
function that had been deleted. (Bug #59546, Bug #11766440)
• The help message for mysql_install_db did not indicate that it supports the --defaults-file, -defaults-extra-file and --no-defaults options. (Bug #58898, Bug #11765888)
• mysql_install_db printed the --skip-grant-tables server option as --skip-grant in one of
its error messages. (Bug #58534, Bug #11765553)
• An assertion designed to detect zero-length sort keys also was raised when the entire key set fit in
memory. (Bug #58200, Bug #11765254)
• During optimization, ZEROFILL values may be converted to string constants. However, CASE
expressions did not handle switching data types after the planning stage, leading to CASE finding a null
pointer instead of its argument. (Bug #57135, Bug #11764313)
224
MySQL 5.6 Release Notes
• If a plugin was uninstalled, thread local variables for plugin variables of string type with wth
PLUGIN_VAR_MEMALLOC flag were not freed. (Bug #56652, Bug #11763882)
• Deadlock could occur when these four things happened at the same time: 1) An old dump thread was
waiting for the binary log to grow. 2) The slave server that replicates from the old dump thread tried
to reconnect. During reconnection, the new dump thread tried to kill the old dump thread. 3) A KILL
statement tried to kill the old dump thread. 4) An INSERT statement caused a binary log rotation. (Bug
#56299, Bug #11763573)
• myisampack could create corrupt FULLTEXT indexes when compressing tables. (Bug #53646, Bug
#11761180)
• The SQL_BIG_RESULT modifier could change the results for queries that included a GROUP BY clause.
(Bug #53534, Bug #11761078)
• ARCHIVE tables with NULL columns could cause server crashes or become corrupt under concurrent
load. (Bug #51252, Bug #11758979)
• InnoDB used incorrect identifier quoting style in an error message that resulted in an error if a user
followed the suggestion in the message. (Bug #49556, Bug #11757503)
• OPTIMIZE TABLE could corrupt MyISAM tables if myisam_use_mmap was enabled. (Bug #49030, Bug
#11757032)
• Concurrent access to ARCHIVE tables could cause corruption. (Bug #42784, Bug #11751793)
• A query that selected a GROUP_CONCAT() function result could return different values depending on
whether an ORDER BY of the function result was present. (Bug #41090, Bug #11750518)
• A linking problem prevented the FEDERATED storage engine plugin from loading. (Bug #40942, Bug
#11750417)
• Subqueries could return incorrect results when materialization was enabled. (Bug #40037, Bug
#11749901, Bug #12705660, Bug #12908058)
• For debug builds, an assertion could be raised for ALTER statements that performed a RENAME
operation. This occurred for storage engine handlertons that exposed the HTON_FLUSH_AFTER_RENAME
flag. (Bug #38028, Bug #11749050)
• The estimate of space required for filesort operations could be too high, resulting in inefficient
initialization. (Bug #37359, Bug #11748783)
• An ALTER TABLE that included an ADD ... AFTER operation to add a new column after a column
that had been modified earlier in the statement failed to find the existing column. (Bug #34972, Bug
#11748057)
• For FEDERATED tables, loss of connection to the remote table during some insert operations could cause
a server crash. (Bug #34660, Bug #11747970)
• For some queries, the index_merge access method was used even when more expensive then ref
access. (Bug #32254, Bug #11747423)
• Collation for the SPACE() function was determined by the parse time value of the
collation_connection system variable (instead of the runtime value), which could give unexpected
results from prepared statements, triggers, and stored procedures. (Bug #23637, Bug #11746123)
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MySQL 5.6 Release Notes
Changes in MySQL 5.6.3 (2011-10-03, Milestone 6)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
• Parallel Event Execution (multi-threaded slave)
• Optimizer Notes
• Performance Schema Notes
• Security Notes
• Functionality Added or Changed
• Bugs Fixed
Parallel Event Execution (multi-threaded slave)
• Replication: MySQL replication now supports a multi-threaded slave executing replication events
from the master across different databases in parallel, which can result in significant improvements in
application throughput when certain conditions are met. The optimum case is that the data be partitioned
per database, and that updates within a given database occur in the same order relative to one another
as they do on the master. However, transactions do not need to be coordinated between different
databases.
The slave_parallel_workers server system variable (added in this release) sets the number of
slave worker threads for executing replication events in parallel. When parallel execution is enabled,
the slave SQL thread acts as the coordinator for the slave worker threads, among which transactions
are distributed on a per-database basis. This means that a worker thread on the slave can process
successive transactions on a given database without waiting for updates on other databases to
complete.
Due to the fact that transactions on different databases can occur in a different order on the slave than
on the master, checking for the most recently executed transaction does not guarantee that all previous
transactions from the master have been executed on the slave. This has implications for logging and
recovery when using a multi-threaded slave. For information about how to interpret binary logging
information when using multi-threading on the slave, see SHOW SLAVE STATUS Syntax.
Optimizer Notes
• These query optimizer improvements were implemented:
• The EXPLAIN statement now provides execution plan information for DELETE, INSERT, REPLACE,
and UPDATE statements. Previously, EXPLAIN provided information only for SELECT statements.
• The optimizer more efficiently handles subqueries in the FROM clause (that is, derived tables):
• Materialization of subqueries in the FROM clause is postponed until their contents are needed
during query execution, which improves performance. Delay of materialization may even enable the
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MySQL 5.6 Release Notes
optimizer to avoid it entirely. Consider a query that joins the result of a subquery in the FROM clause
to another table: If the optimizer processes that other table first and finds that it returns no rows, the
join need not be carried out further and the optimizer need not materialize the subquery at all.
Previously, subqueries in the FROM clause were materialized for EXPLAIN SELECT statements.
This resulted in partial SELECT execution, even though the purpose of EXPLAIN is to obtain query
plan information, not to execute the query. This materialization no longer occurs, so EXPLAIN is
faster for such queries.
• During query execution, the optimizer may add an index to a derived table to speed up row retrieval
from it.
For more information, see Optimizing Derived Tables.
• A Batched Key Access (BKA) join algorithm is now available that uses both index access to the joined
table and a join buffer. The BKA algorithm supports inner join and outer join operations, including
nested outer joins. Benefits of BKA include improved join performance due to more efficient table
scanning.
Two flags have been added to the optimizer_switch system variable (block_nested_loop
and batched_key_access). These flags control how the optimizer uses the Block Nested-Loop
and Batched Key Access join algorithms. Previously, the optimizer_join_cache_level system
variable was used for join buffer control; this variable has been removed.
For more information, see Block Nested-Loop and Batched Key Access Joins.
• The optimizer now has a tracing capability. This will be of use to optimizer developers, and also to
users who file bugs against the optimizer and want to provide more information that will help resolve
the bug. The interface is provided by a set of optimizer_trace_xxx system variables and the
INFORMATION_SCHEMA.OPTIMIZER_TRACE table, but is subject to change. For details, see MySQL
Internals: Tracing the Optimizer.
(Bug #44802, Bug #11753371, Bug #14295, Bug #11745379, Bug #27975, Bug #11746677)
Performance Schema Notes
• The Performance Schema has these additions:
• The Performance Schema now instruments stages and statements. Stages are steps during
the statement-execution process, such as parsing a statement, opening a table, or performing a
filesort operation. Stages correspond to the thread states displayed by SHOW PROCESSLIST or
that are visible in the INFORMATION_SCHEMA.PROCESSLIST table. Stages begin and end when state
values change.
Within the event hierarchy, wait events nest within stage events, which nest within statement
events. To reflect this nesting in wait-event tables such as events_waits_current, the
NESTING_EVENT_ID column now can be non-NULL to indicate the EVENT_ID value of the event
within which an event is nested, and NESTING_EVENT_TYPE is a new column indicating the type of
the nesting event.
The setup_instruments table now contains instruments with names that begin with stage and
statement. Corresponding to these instruments, the setup_timers table now contains rows with
NAME values of stage and statement that indicate the unit for stage and statement event timing.
The default unit for each is NANOSECOND.
These new tables store stage and statement events:
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MySQL 5.6 Release Notes
• events_stages_current: Current stage events
• events_stages_history: The most recent stage events for each thread
• events_stages_history_long: The most recent stage events overall
• events_statements_current: Current statement events
• events_statements_history: The most recent statement events for each thread
• events_statements_history_long: The most recent statement events overall
The setup_consumers table now contains consumer values with names corresponding to those
table names. These consumers may be used to filter collection of stage and statement events.
There are also summary tables that provide aggregated stage and statement information.
Application developers can use statement instrumentation to see in detail the statements generated
by an application, and how these statements are executed by the server. Stage instrumentation can
be used to focus on particular parts of statements. This information may be useful to change how an
application issues queries against the database, to minimize the application footprint on the server,
and to improve application performance and scalability.
For more information, see Performance Schema Stage Event Tables, Stage Summary Tables,
Performance Schema Statement Event Tables, and Statement Summary Tables.
• The Performance Schema now provides statistics about connections to the server. When a client
connects, it does so under a particular user name and from a particular host. The Performance
Schema tracks connections per account (user name plus host name) and separately per user name
and per host name, using these tables:
• accounts: Connection statistics per client account
• hosts: Connection statistics per client host name
• users: Connection statistics per client user name
There are also summary tables that provide aggregated connection information.
It is good security practice to define a dedicated account per application, so that an application is
given privileges to perform only those actions that it needs during its operation. This also facilitates
monitoring because the information in the connection tables can be used by application developers
to see load statistics per application when deploying several applications against a given database
server.
For more information, see Performance Schema Connection Tables.
• Previously, the setup_objects table could be used only to specify by inclusion which objects
to instrument. There was no way to explicitly disable object instrumentation, such as to configure
instrumention for all tables except those in a particular database. Now the setup_objects table
includes an ENABLED column that indicates whether to instrument matching objects. This feature
improves the setup_objects table usability because it permits exclusion patterns.
The default table contents now include a row that disables instrumentation for tables in the mysql
database, which is a change from the previous default object instrumentation. This change is chosen
assuming that end users want to instrument application objects, not internal server tables. The change
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MySQL 5.6 Release Notes
reduces the default Performance Schema overhead because I/O and locks on mysql tables are not
instrumented.
The table also includes rows that disable instrumentation for tables in the INFORMATION_SCHEMA and
performance_schema databases. This is not a change in behavior because those tables were not
instrumented before, but these rows make the full object instrumentation defaults explicit.
• The Performance Schema now instruments sockets. This enables monitoring of network
communication to and from the server. Information collected includes network activity such as socket
instances, socket operations, and number of bytes transmitted and received.
The setup_instruments table now contains instruments with names that begin with wait/io/
socket. There is also an idle instrument used for idle events when a socket is waiting for the
next request from the client. Corresponding to the latter instrument, the setup_timers table now
contains a row with a NAME value of idle that indicates the unit for idle event timing. The default unit
is MICROSECOND.
These new tables contain socket information:
• socket_instances: A real-time snapshot of the active connections to the MySQL server
• socket_summary_by_instance: Aggregate timer and byte count statistics generated by the
wait/io/socket/* instruments for all socket I/O operations, per socket instance
• socket_summary_by_event_name: Aggregate timer and byte count statistics generated by the
wait/io/socket/* instruments for all socket I/O operations, per socket instrument
The information in the socket tables can be used by application developers, particularly those
developing web-based applications, to assess the volume of network traffic directly attributable
to queries generated by their application. This can be particularly useful during development of
applications intended for large-scale implementations.
For more information, see The socket_instances Table, and Socket Summary Tables.
As a consequence of these changes, the Opening table thread state has been removed. The
Opening tables state remains and can be used instead. (See General Thread States.)
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the performance_schema database.
Security Notes
• For temporary tables created with the CREATE TEMPORARY TABLE statement, the privilege model has
changed.
Previously, the CREATE TEMPORARY TABLES privilege enabled users to create temporary tables with
the CREATE TEMPORARY TABLE statement. However, other operations on a temporary table, such
as INSERT, UPDATE, or SELECT, required additional privileges for those operations for the database
containing the temporary table, or for the nontemporary table of the same name.
To keep privileges for temporary and nontemporary tables separate, a common workaround for this
situation was to create a database dedicated to the use of temporary tables. Then for that database,
a user could be granted the CREATE TEMPORARY TABLES privilege, along with any other privileges
required for temporary table operations done by that user.
Now, the CREATE TEMPORARY TABLES privilege enables users to create temporary tables with CREATE
TEMPORARY TABLE, as before. However, after a session has created a temporary table, the server
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MySQL 5.6 Release Notes
performs no further privilege checks on the table. The creating session can perform any operation on the
table, such as DROP TABLE, INSERT, UPDATE, or SELECT.
One implication of this change is that a session can manipulate its temporary tables even if the
current user has no privilege to create them. Suppose that the current user does not have the CREATE
TEMPORARY TABLES privilege but is able to execute a DEFINER-context stored procedure that executes
with the privileges of a user who does have CREATE TEMPORARY TABLES and that creates a temporary
table. While the procedure executes, the session uses the privileges of the defining user. After the
procedure returns, the effective privileges revert to those of the current user, which can still see the
temporary table and perform any operation on it. (Bug #27480, Bug #11746602)
• Statement logging has been modified so that passwords do not appear in plain text for the following
statements:
CREATE USER ... IDENTIFIED BY ...
GRANT ... IDENTIFIED BY ...
SET PASSWORD ...
Passwords in those statements are rewritten not to appear literally in statement text, for the general
query log, slow query log, and binary log. Rewriting does not apply to other statements.
For the general query log, password rewriting can be suppressed by starting the server with the --lograw option. This option may be useful for diagnostic purposes, to see the exact text of statements as
received by the server, but for security reasons is not recommended for production use.
One change you will notice is that statements that cannot be parsed (due, for example, to syntax errors)
are no longer written to the general query log because they cannot be known to be password free. Use
cases that require logging of all statements including those with errors should use the --log-raw
option, bearing in mind that this also bypasses password writing.
Functionality Added or Changed
• Incompatible Change: In the audit plugin interface, the event_class member was removed from the
mysql_event_general structure and the calling sequence for the notification function was changed.
Originally, the second argument was a pointer to the event structure. The function now receives this
information as two arguments: an event class number and a pointer to the event. Corresponding to these
changes, MYSQL_AUDIT_INTERFACE_VERSION was increased to 0x0300.
The plugin_audit.h header file, and the NULL_AUDIT example plugin in the plugin/audit_null
directory were modified per these changes. See Writing Audit Plugins.
• Important Change; Replication: The RESET SLAVE statement has been extended with an ALL
keyword. In addition to deleting the master.info, relay-log.info, and all relay log files, RESET
SLAVE ALL also clears all connection information otherwise held in memory following execution of
RESET SLAVE. (Bug #11809016, Bug #11763210)
• Performance; InnoDB: At shutdown, MySQL can record the pages that are cached in the
InnoDB buffer pool, then reload those same pages upon restart. This technique can help
to quickly reach consistent throughput after a restart, without a lengthy warmup period. This
preload capability uses a compact save format and background I/O to minimize overhead on the
MySQL server. The basic dump/restore capability is enabled through the configuration options
innodb_buffer_pool_dump_at_shutdown and innodb_buffer_pool_load_at_startup.
Related configuration options such as innodb_buffer_pool_dump_now and
innodb_buffer_pool_load_now offer extra flexibility for advanced users to configure the MySQL
server for different workloads. See Saving and Restoring the Buffer Pool State for details. (Bug
#11765816, Bug #58819)
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MySQL 5.6 Release Notes
• Performance; InnoDB: When innodb_file_per_table is enabled, each InnoDB table is created
in its own tablespace file (.ibd file). As data inside the table grows, the .ibd file is extended, which is
an I/O operation that may create a bottleneck for busy systems with many InnoDB tables. For InnoDB
tables that are stored inside the system tablespace, the extension operation happens less frequently, as
space freed by DELETE or TRUNCATE operations within one table can be reused by another table.
MySQL 5.6 improves concurrency for extending InnoDB tablespace files (.ibd files), so that multiple
.ibd files can be extended simultaneously without blocking read or write operations performed by other
threads. (Bug #11763692, Bug #56433)
• Performance; InnoDB: You can improve the efficiency of the InnoDB checksum feature by specifying
the configuration option innodb_checksum_algorithm=crc32, which turns on a faster checksum
algorithm. This option replaces the innodb_checksums option. Data written using the old checksum
algorithm (option value innodb) is fully upward-compatible; tablespaces modified using the new
checksum algorithm (option value crc32) cannot be downgraded to an earlier version of MySQL that
does not support the innodb_checksum_algorithm option. (Bug #11757757, Bug #49852)
• Performance; InnoDB: The code that detects deadlocks in InnoDB transactions has been modified to
use a fixed-size work area rather than a recursive algorithm. The resulting detection operation is faster
as a result. You do not need to do anything to take advantage of this enhancement.
Under both the old and new detection mechanisms, you might encounter a search too deep error
that is not a true deadlock, but requires you to re-try the transaction the same way as with a deadlock.
• Performance; InnoDB: The InnoDB thread-scheduling code has been enhanced to work better with
greater than 16 threads. Where possible, atomic instructions are used. You control this feature by setting
the configuration option innodb_thread_concurrency to a nonzero value, and adjusting the value of
innodb_adaptive_max_sleep_delay. See Configuring Thread Concurrency for InnoDB for details.
• Performance; InnoDB: Work continues to offload flush operations from the InnoDB main thread,
doing them in the page_cleaner thread instead. The latest changes to the buffer pool flushing
algorithms can improve performance for some I/O-bound workloads, particularly in configurations
with multiple buffer pool instances. You control this feature by adjusting the settings for the
innodb_lru_scan_depth and innodb_flush_neighbors configuration options. To find the
optimal settings, test each combination of the above settings with both the Adaptive Hash Index and the
Doublewrite Buffer turned on and off. See Fine-tuning InnoDB Buffer Pool Flushing for more details.
• Performance; InnoDB: This feature optionally moves the InnoDB undo log out of the system
tablespace into one or more separate tablespaces. The I/O patterns for the undo log make
these new tablespaces good candidates to move to SSD storage, while keeping the system
tablespace on hard disk storage. This feature is controlled by the configuration options
innodb_undo_directory, innodb_undo_tablespaces, and innodb_undo_logs (formerly
known as innodb_rollback_segments). Users cannot drop the separate tablespaces created to hold
InnoDB undo logs, or the individual segments inside those tablespaces.
MySQL instances configured this way are not downward-compatible; older versions of MySQL cannot
access the undo logs that reside in their own tablespace.
For details, see Configuring Undo Tablespaces.
• InnoDB: InnoDB now permits concurrent reads while creating a secondary index. (Bug #11853126)
References: See also: Bug #11751388, Bug #11784056, Bug #11815600.
• InnoDB: The InnoDB redo log files now have a maximum combined size of 512GB, increased from
4GB. You can specify the larger values through the innodb_log_file_size option.
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MySQL 5.6 Release Notes
There is no special upgrade process or file format to take advantage of this enhancement. The bytes that
record the extra size information were already reserved in the InnoDB system tablespace. However, if
you develop applications that interact with the InnoDB logical sequence number (LSN) value, change
your code to use guaranteed 64-bit variables to store and compare LSN values, rather than 32-bit
variables. (Bug #11765780, Bug #58779)
• InnoDB: InnoDB tables can now be created with character sets whose collation ID is greater than 255.
For example, the following InnoDB table can now be created, where formerly the collation ID of 359 was
beyond the range supported by InnoDB.
mysql> show collation like 'ucs2_vn_ci';
+------------+---------+-----+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+------------+---------+-----+---------+----------+---------+
| ucs2_vn_ci | ucs2
| 359 |
|
|
8 |
+------------+---------+-----+---------+----------+---------+
1 row in set (0.00 sec)
mysql> CREATE TABLE two_byte_collation (c1 char(1) CHARACTER SET UCS2 COLLATE UCS2_VN_CI)
-> ENGINE = INNODB;
Query OK, 0 rows affected (0.16 sec)
This capability opens up InnoDB tables for use with a range of user-defined character sets. MySQL
predefined character sets have previously been limited to a maximum of 255, and now that restriction is
lifted. See Choosing a Collation ID for more information.
• Replication: MySQL 5.6.1 added timestamps to the error messages shown in the Last_IO_Error
and Last_SQL_Error columns of the output of SHOW SLAVE STATUS. Now these timestamps
are shown in separate columns of their own, named Last_IO_Error_Timestamp and
Last_SQL_Error_Timestamp, respectively. (Bug #11765599, Bug #58584)
References: See also: Bug #43535, Bug #11752361.
• Replication: BEGIN, COMMIT, and ROLLBACK statements are now cached along with the statements
instead of being written when the cache is flushed to the binary log. This change does not affect DDL
statements—which are written into the statement cache, then immediately flushed—or Incident events
(which, along with Rotate events, are still written directly to the binary log).
References: See also: Bug #57275, Bug #11764443.
• Microsoft Windows: The Windows installer now creates an item in the MySQL menu named MySQL
command line client - Unicode. This item invokes the mysql client with properties set to
communicate through the console to the MySQL server using Unicode. It passes the --defaultcharacter-set=utf8 option to mysql and sets the font to the Lucida Console Unicodecompatible font. See Unicode Support on Windows.
• Following EXPLAIN EXTENDED, a change has been made to the transformed query displayed by SHOW
WARNINGS. Each SELECT part now is preceded by the id value from the associated EXPLAIN output
row. This makes it easier to see the correspondence between those rows and parts of the transformed
query. For example, this query:
EXPLAIN EXTENDED SELECT 36 FROM DUAL
results in:
/* select#1 */ select 36 from dual
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MySQL 5.6 Release Notes
And this query:
EXPLAIN EXTENDED SELECT a FROM t
WHERE a IN (SELECT b FROM u UNION SELECT c from v)
results in:
/* select#1 */ select a from t where a in (/* select#2 */
select b from u union /* select#3 */ select c from v);
(Bug #13035597)
• Several memory allocation calls were eliminated, resulting in improved performance. (Bug #12552221)
• CMake configuration support on Linux now provides a boolean ENABLE_GCOV option to control whether
to include support for gcov. (Bug #12549572)
• Previously, Performance Schema instrumentation for both the binary log and the relay log used these
instruments:
wait/io/file/sql/binlog
wait/io/file/sql/binlog_index
wait/synch/mutex/sql/MYSQL_BIN_LOG::LOCK_index
wait/synch/cond/sql/MYSQL_BIN_LOG::update_cond
Now instrumentation for the relay log uses these instruments, which makes it possible to distinguish
binary log and relay log events:
wait/io/file/sql/relaylog
wait/io/file/sql/relaylog_index
wait/synch/mutex/sql/MYSQL_RELAY_LOG::LOCK_index
wait/synch/cond/sql/MYSQL_RELAY_LOG::update_cond
(Bug #59658, Bug #11766528)
• A new server option, --plugin-load-add, complements the --plugin-load option. --pluginload-add adds a plugin or plugins to the set of plugins to be loaded at startup. The argument format is
the same as for --plugin-load. --plugin-load-add can be used to avoid specifying a large set of
plugins as a single long unwieldy --plugin-load argument.
--plugin-load-add can be given in the absence of --plugin-load, but any instance of -plugin-load-add that appears before --plugin-load. has no effect because --plugin-load
resets the set of plugins to load.
This change affects the output of mysqld --verbose --help in that a value for plugin-load is no
longer printed. (Bug #59026, Bug #11766001)
• When invoked with the --auto-generate-sql option, mysqlslap dropped the schema specified with
the --create-schema option at the end of the test run, which may have been unexpected by the user.
mysqlslap now has a --no-drop option that prevents any schema created during the test run from
being dropped. (Bug #58090, Bug #11765157)
• The server now exposes SSL certificate expiration dates through the Ssl_server_not_before
and Ssl_server_not_after status variables. Both variables have values in ANSI time format (for
example, Sep 12 16:22:06 2013 GMT), or are blank for non-SSL connections. (Bug #57648, Bug
#11764778)
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MySQL 5.6 Release Notes
• Previously, TEMPORARY tables created with CREATE TEMPORARY TABLES had the default storage
engine unless the definition included an explicit ENGINE option. (The default engine is the value of
the default_storage_engine system variable.) Since MySQL 5.5.5, when the default storage
engine was changed from the nontransactional MyISAM engine to the transactional InnoDB engine,
TEMPORARY tables have incurred the overhead of transactional processing.
To permit the default storage engine for TEMPORARY tables to be set independently of the default engine
for permanent tables, the server now supports a default_tmp_storage_engine system variable.
For example, to create TEMPORARY tables as nontransactional tables by default, start the server with
--default_tmp_storage_engine=MyISAM. The storage engine for TEMPORARY tables can still be
specified on an individual basis by including an ENGINE option in table definitions. (Bug #49232, Bug
#11757216)
• Previously, for MySQL binaries linked against OpenSSL, if an SSL key file supplied to the MySQL server
or a MySQL client program (using the --ssl-key option) was protected by a passphrase, the program
would prompt the user for the passphrase. This is now also the case for MySQL binaries linked against
yaSSL. (Bug #44559, Bug #11753167)
• The mysql client program now has a --binary-mode option that helps when processing
mysqlbinlog output that may contain BLOB values. By default, mysql translates \r\n in statement
strings to \n and interprets \0 as the statement terminator. --binary-mode disables both features. It
also disables all mysql commands except charset and delimiter in non-interactive mode (for input
piped to mysql or loaded using the source command). (Bug #33048, Bug #11747577)
• MySQL binaries linked against OpenSSL (but not yaSSL) now support certificate revocation lists for SSL
connections:
• The MySQL server and MySQL client programs that support SSL recognize --ssl-crl and --sslcrlpath options for specifying a revocation list file or directory containing such files.
• The ssl_crl and ssl_crlpath system variables indicate the values of the --ssl-crl and -ssl-crlpath options with which the server was started.
• The CHANGE MASTER TO statement has MASTER_SSL_CRL and MASTER_SSL_CRLPATH options
for specifying revocation list information to use when the slave connects to the master. The
mysql.slave_master_info file has two more rows to store the values of these options. The SHOW
SLAVE STATUS statement has two more columns to display the values of these options.
The mysql_options() C API function has MYSQL_OPT_SSL_CRL and MYSQL_OPT_SSL_CRLPATH
options for specifying revocation list information to use when the client connects to the master. In
addition, mysql_options() now also supports MYSQL_OPT_SSL_CA, MYSQL_OPT_SSL_CAPATH,
MYSQL_OPT_SSL_CERT, MYSQL_OPT_SSL_CIPHER, and MYSQL_OPT_SSL_KEY options for
specifying other SSL parameters.
(Bug #31224, Bug #11747191)
• mysqld now has an --ignore-db-dir option that tells the server to ignore a given name for purposes
of the SHOW DATABASES statement or INFORMATION_SCHEMA tables. For example, if a MySQL
configuration locates the data directory at the root of a file system on Unix, the system might create a
lost+found directory there that the server should ignore. Starting the server with --ignore-dbdir=lost+found causes that name not to be listed as a database.
To specify more than one name, use this option multiple times, once for each name. Specifying the
option with an empty value (that is, as --ignore-db-dir=) resets the directory list to the empty list.
Instances of this option given at server startup are used to set the ignore_db_dirs system variable.
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MySQL 5.6 Release Notes
In addition to directories named by --ignore-db-dir, directories having a name that begins with a
period are ignored. (Bug #22615, Bug #11746029)
• Client programs now display more information for SSL errors to aid in diagnosis and debugging of
connection problems. (Bug #21287, Bug #11745920)
• Some plugins operate in such a matter that they should be loaded at server startup, and not loaded or
unloaded at runtime. The plugin API now supports marking plugins this way. The st_mysql_plugin
structure now has a flags member, which can be set to the OR of the applicable flags. The
PLUGIN_OPT_NO_INSTALL flag indicates that the plugin cannot be loaded at runtime with the INSTALL
PLUGIN statement. This is appropriate for plugins that must be loaded at server startup with the -plugin-load option. The PLUGIN_OPT_NO_UNINSTALL flag indicates that the plugin cannot be
unloaded at runtime with the UNINSTALL PLUGIN statement.
The new member changes the interface, so the plugin interface version,
MYSQL_PLUGIN_INTERFACE_VERSION, has been incremented from 0x0102 to 0x0103. Plugins that
require access to the new member must be recompiled to use version 0x0103 or higher.
• A new utility, mysql_plugin, enables MySQL administrators to manage which plugins a MySQL server
loads. It provides an alternative to manually specifying the --plugin-load option at server startup or
using the INSTALL PLUGIN and UNINSTALL PLUGIN statements at runtime. See mysql_plugin —
Configure MySQL Server Plugins.
• The following items are deprecated and will be removed in a future MySQL release. Where alternatives
are shown, applications should be updated to use them.
• The innodb_table_monitor table. Similar information can be obtained from InnoDB
INFORMATION_SCHEMA tables. See InnoDB INFORMATION_SCHEMA Tables.
• The innodb_locks_unsafe_for_binlog system variable.
• The innodb_stats_sample_pages system variable. Use
innodb_stats_transient_sample_pages instead.
• The innodb_use_sys_malloc and the innodb_additional_mem_pool_size system variables.
• The undocumented --all option for perror has been removed. Also, perror no longer displays
messages for BDB error codes.
• MySQL now includes support for manipulating IPv6 network addresses and for validating IPv4 and IPv6
addresses:
• The INET6_ATON() and INET6_NTOA() functions convert between string and numeric forms of IPv6
addresses. Because numeric-format IPv6 addresses require more bytes than the largest integer type,
the representation uses the VARBINARY data type.
• The IS_IPV4() and IS_IPV6() functions test whether a string value represents a valid IPv4 or IPv6
address. The IS_IPV4_COMPAT() and IS_IPV4_MAPPED() functions test whether a numeric-format
value represents a valid IPv4-compatible or IPv4-mapped address.
• No changes were made to the INET_ATON() or INET_NTOA() functions that manipulate IPv4
addresses.
IS_IPV4() is more strict than INET_ATON() about what constitutes a valid IPv4 address, so it may
be useful for applications that need to perform strong checks against invalid values. Alternatively, use
235
MySQL 5.6 Release Notes
INET6_ATON() to convert IPv4 addresses to internal form and check for a NULL result (which indicates
an invalid address). INET6_ATON() is equally strong as IS_IPV4() about checking IPv4 addresses.
• The max_allowed_packet system variable now controls the maximum size of parameter values that
can be sent with the mysql_stmt_send_long_data() C API function.
• The NULL_AUDIT example plugin in the plugin/audit_null directory has been updated to count
instances of events in the MYSQL_AUDIT_CONNECTION_CLASS event class. See Writing Audit Plugins.
Bugs Fixed
• Security Fix: A security bug was fixed. (Bug #59533)
• Incompatible Change: For socket I/O, an optimization for the case when the server used alarms for
timeouts could cause a slowdown when socket timeouts were used instead.
The fix for this issue results in several changes:
• Previously, timeouts applied to entire packet-level send or receive operations. Now timeouts apply to
individual I/O operations at a finer level, such as sending 10 bytes of a given packet.
• The handling of packets larger than max_allowed_packet has changed. Previously, if an
application sent a packet bigger than the maximum permitted size, or if the server failed to allocate
a buffer sufficiently large to hold the packet, the server kept reading the packet until its end, then
skipped it and returned an ER_NET_PACKET_TOO_LARGE error. Now the server disconnects the
session if it cannot handle such large packets.
• On Windows, the default value for the MYSQL_OPT_CONNECT_TIMEOUT option to mysql_options()
is no longer 20 seconds. Now the default is no timeout (infinite), the same as on other platforms.
• Building and running MySQL on POSIX systems now requires support for poll() and O_NONBLOCK.
These should be available on any modern POSIX system.
(Bug #54790, Bug #36225, Bug #11762221, Bug #51244, Bug #11758972)
• Incompatible Change: The mysql_affected_rows() C API function returned 3 (instead of 2) for
INSERT ... ON DUPLICATE KEY UPDATE statements where there was a duplicated key value.
Now the affected-rows value per row is 1 if the row is inserted as a new row, 2 if an existing row is
updated, and 0 if an existing row is set to its current values. If you specify the CLIENT_FOUND_ROWS
flag to mysql_real_connect() when connecting to mysqld, the affected-rows value is 1 (not 0) if an
existing row is set to its current values. (Bug #46675, Bug #11754979)
• Incompatible Change: Handling of a date-related assertion was modified. A consequence of this
change is that several functions become more strict when passed a DATE() function value as
their argument and reject incomplete dates with a day part of zero. These functions are affected:
CONVERT_TZ(), DATE_ADD(), DATE_SUB(), DAYOFYEAR(), LAST_DAY(), TIMESTAMPDIFF(),
TO_DAYS(), TO_SECONDS(), WEEK(), WEEKDAY(), WEEKOFYEAR(), YEARWEEK().
It was later determined that stricter handling is unnecessary for LAST_DAY(), which was reverted to
permit a zero day part in MySQL 5.6.5.
References: See also: Bug #13458237.
• Performance; InnoDB: This fix improves the performance of operations on VARCHAR(N) columns in
InnoDB tables, where N is declared as a large value but the actual string values in the table are short.
(Bug #12835650)
236
MySQL 5.6 Release Notes
• Performance; InnoDB: The mechanism that InnoDB uses to detect if the MySQL server is idle was
made more accurate, to avoid slowdown due to flush operations that normally occur when no other
activity is taking place. The mechanism now considers that the server is not idle if there are pending read
requests for the InnoDB buffer pool. (Bug #11766123, Bug #59163)
• InnoDB; Replication: Trying to update a column, previously set to NULL, of an InnoDB table with no
primary key caused replication to fail on the slave with Can't find record in 'table'.
Note
This issue was inadvertently reintroduced in MySQL 5.6.6, and fixed again in
MySQL 5.6.12.
(Bug #11766865, Bug #60091)
References: See also: Bug #16566658.
• InnoDB: The DATA_LENGTH column in the INFORMATION_SCHEMA.TABLES table now correctly reports
the on-disk sizes of tablespaces for InnoDB compressed tables. (Bug #12770537)
• InnoDB: A failed CREATE INDEX operation for an InnoDB table could result in some memory being
allocated but not freed. This memory leak could affect tables created with the ROW_FORMAT=DYNAMIC or
ROW_FORMAT=COMPRESSED setting. (Bug #12699505)
• InnoDB: With the configuration settings innodb_file_per_table=1 and
innodb_file_format=Barracuda, inserting a column value greater than half the page size, and
including that column in a secondary index, could cause a crash when that column value was updated.
(Bug #12637786)
• InnoDB: The underlying tables to support the InnoDB persistent statistics feature were renamed and
moved into the mysql database. innodb.table_stats became mysql.innodb_table_stats, and
innodb.index_stats became mysql.innodb_index_stats. (Bug #12604399)
• InnoDB: The server could halt if InnoDB interpreted a very heavy I/O load for 15 minutes or more as
an indication that the server was hung. This change fixes the logic that measures how long InnoDB
threads were waiting, which formerly could produce false positives. (Bug #11877216, Bug #11755413,
Bug #47183)
• InnoDB: With the setting lower_case_table_names=2, inserts into InnoDB tables covered by
foreign key constraints could fail after a server restart. (Bug #11831040, Bug #60196, Bug #60909)
• InnoDB: If the MySQL Server crashed immediately after creating an InnoDB table, attempting to access
the table after restart could cause another crash. The issue could occur if the server halted after InnoDB
created the primary index for the table, but before the index definition was recorded in the MySQL
metadata. (Bug #11766824, Bug #60042)
• InnoDB: If the server crashed while an XA transaction was prepared but not yet committed, the
transaction could remain in the system after restart, and cause a subsequent shutdown to hang. (Bug
#11766513, Bug #59641)
• InnoDB: The MySQL server could hang during CREATE TABLE, OPTIMIZE TABLE, or ALTER TABLE
or other DDL operation that performs a table copy for an InnoDB table, if such operations were
performed by multiple sessions simultaneously. The error was reported as:
InnoDB: Error: semaphore wait has lasted > 600 seconds
(Bug #11760042, Bug #52409)
237
MySQL 5.6 Release Notes
• InnoDB: With the setting lower_case_table_names=2, inserts into InnoDB tables covered by
foreign key constraints could fail after a server restart. This is a similar problem to the foreign key error in
Bug #11831040 / Bug #60196 / Bug #60909, but with a different root cause and occurring on OS X.
• Partitioning: The internal get_partition_set() function did not take into account the possibility that
a key specification could be NULL in some cases. (Bug #12380149)
• Partitioning: When executing a row-ordered retrieval index merge, the partitioning handler used
memory from that allocated for the table, rather than that allocated to the query, causing table object
memory not to be freed until the table was closed. (Bug #11766249, Bug #59316)
• Partitioning: Attempting to use ALTER TABLE ... EXCHANGE PARTITION to exchange a view with
a (nonexistent) partition of a table that was not partitioned caused the server to crash. (Bug #11766232,
Bug #60039)
• Partitioning: Auto-increment columns of partitioned tables were checked even when they were not
being written to. In debug builds, this could lead to a server crash. (Bug #11765667, Bug #58655)
• Partitioning: The UNIX_TIMESTAMP() function was not treated as a monotonic function for purposes
of partition pruning. (Bug #11746819, Bug #28928)
• Partitioning: A problem with a previous fix for poor performance of INSERT ON DUPLICATE KEY
UPDATE statements on tables having many partitions caused the handler function for reading a row from
a specific index to fail to store the ID of the partition last used. This caused some statements to fail with
Can't find record errors. (Bug #59297, Bug #11766232)
References: This issue is a regression of: Bug #52455.
• Replication: A mistake in thread cleanup could cause a replication master to crash. (Bug #12578441)
• Replication: When using row-based replication and attribute promotion or demotion (see Replication of
Columns Having Different Data Types), memory allocated internally for conversion of BLOB columns was
not freed afterwards. (Bug #12558519)
• Replication: A memory leak could occur when re-creating a missing master info repository, because a
new I/O cache used for a reference to the repository was re-created when the repository was re-created,
but the previous cache was never removed. (Bug #12557307)
• Replication: A race condition could occur between a user thread and the SQL thread when both tried to
read the same memory before its value was safely set. This issue has now been corrected.
In addition, internal functions relating to creation of and appending to log events, when storing data, used
memory local to the functions which was freed when the functions returned. As part of the fix for this
problem, the output of SHOW SLAVE STATUS has been modified such that it no longer refers to files
or file names in the accompanying status message, but rather contains one of the messages Making
temporary file (append) before replaying LOAD DATA INFILE or Making temporary
file (create) before replaying LOAD DATA INFILE. (Bug #12416611)
• Replication: The name of the Ssl_verify_server_cert column in the
mysql.slave_master_info table was misspelled as Ssl_verify_servert_cert. (Bug
#12407446, Bug #60988)
• Replication: When mysqlbinlog was invoked using --base64-output=decode-row and -start-position=pos, (where pos is a point in the binary log past the format description log event), a
spurious error of the type shown here was generated:
malformed binlog: it does not contain any Format_description_log_event...
238
MySQL 5.6 Release Notes
However, since there is nothing unsafe about not printing the format description log event, the error has
been removed for this case. (Bug #12354268)
• Replication: A failed CREATE USER statement was mistakenly written to the binary log. (Bug
#11827392, Bug #60082)
• Replication: It is no longer possible to change the storage engine used by the
mysql.slave_master_info and mysql.slave_relay_log_info tables while replication is
running. This means that, to make replication crash-safe, you must make sure that both of these tables
use a transactional storage engine before starting replication.
For more information, see Replication Relay and Status Logs, and Options for Logging Slave Status to
Tables. (Bug #11765887, Bug #58897)
• Replication: A transaction was written to the binary log even when it did not update any
nontransactional tables. (Bug #11763471, Bug #56184)
References: See also: Bug #11763126, Bug #55789.
• Replication: mysqlbinlog using the --raw option did not function correctly with binary logs from
MySQL Server versions 5.0.3 and earlier. (Bug #11763265, Bug #55956)
• Replication: Retrying a transaction on the slave could insert extra data into nontransactional tables.
(Bug #11763126, Bug #55789)
References: See also: Bug #11763471, Bug #56184.
• Replication: Typographical errors appeared in the text of several replication error messages. (The word
“position” was misspelled as “postion”.) (Bug #11762616, Bug #55229)
• Replication: Temporary deadlocks in the slave SQL thread could cause unnecessary Deadlock
found when trying to get lock; try restarting transaction error messages to be
logged on the slave.
Now in such cases, only a warning is logged unless slave_transaction_retries has been
exceeded by the number of such warnings for a given transaction. (Bug #11748510, Bug #36524)
• Replication: When a slave requested a binary log file which did not exist on the master, the slave
continued to request the file regardless. This caused the slave's error log to be flooded with low-level
EE_FILENOTFOUND errors (error code 29) from the master. (Bug #11745939, Bug #21437)
• Replication: If a LOAD DATA INFILE statement—replicated using statement-based replication—
featured a SET clause, the name-value pairs were regenerated using a method (Item::print())
intended primarily for generating output for statements such as EXPLAIN EXTENDED, and which cannot
be relied on to return valid SQL. This could in certain cases lead to a crash on the slave.
To fix this problem, the server now names each value in its original, user-supplied form, and uses that to
create LOAD DATA INFILE statements for statement-based replication. (Bug #60580, Bug #11902767)
References: See also: Bug #34283, Bug #11752526, Bug #43746.
• Replication: Error 1590 (ER_SLAVE_INCIDENT) caused the slave to stop even when it was started with
--slave-skip-errors=1590. (Bug #59889, Bug #11768580, Bug #11799671)
• Replication: Using the --server-id option with mysqlbinlog could cause format description log
events to be filtered from the binary log, leaving mysqlbinlog unable to read the remainder of the log.
Now such events are always read without regard to the value of this option.
239
MySQL 5.6 Release Notes
As part of the fix for this problem, mysqlbinlog now also reads rotate log events without regard to the
value of --server-id. (Bug #59530, Bug #11766427)
• Replication: A failed DROP DATABASE statement could break statement-based replication. (Bug
#58381, Bug #11765416)
• Replication: Processing of corrupted table map events could cause the server to crash. This was
especially likely if the events mapped different tables to the same identifier, such as could happen due to
Bug #56226.
Now, before applying a table map event, the server checks whether the table has already been mapped
with different settings, and if so, an error is raised and the slave SQL thread stops. If it has been
mapped with the same settings, or if the table is set to be ignored by filtering rules, there is no change in
behavior: the event is skipped and IDs are not checked. (Bug #44360, Bug #11753004)
References: See also: Bug #56226, Bug #11763509.
• OS X: Compilation failed on OS X 10.7 (Lion) with a warning: Implicit declaration of
function 'pthread_init' (Bug #12779790)
• Microsoft Windows: Adding support for Windows authentication to libmysqlclient introduced a link
dependency on the system Secur32 library. The Microsoft Visual C++ link information now pulls in this
library automatically. (Bug #12612143)
• Microsoft Windows: On Windows, the server rejected client connections if no DNS server was
available. (Bug #12325375)
• Microsoft Windows: On Windows, the authentication_string column recently added to the
mysql.user table caused the Configuration Wizard to fail. (Bug #59038, Bug #11766011)
• The Performance Schema caused a bottleneck for LOCK_open. (Bug #12993572)
• mysqld_safe ignored any value of plugin_dir specified in my.cnf files. (Bug #12925024)
• The metadata locking subsystem added too much overhead for INFORMATION_SCHEMA queries that
were processed by opening only .frm or .TRG files and had to scan many tables. For example, SELECT
COUNT(*) FROM INFORMATION_SCHEMA.TRIGGERS was affected. (Bug #12828477)
• The result for ANY subqueries with nested joins could be missing rows. (Bug #12795555)
• With profiling disabled or not compiled in, set_thd_proc_info() unnecessarily checked file name
lengths. (Bug #12756017)
References: This issue is a regression of: Bug #59273.
• Compiling the server with maintainer mode enabled failed for gcc 4.6 or higher. (Bug #12727287)
• For prepared statements, an OK could be sent to the client if the prepare failed due to being killed. (Bug
#12661349)
• Some Valgrind warnings were corrected:
• For the SUBSTRING(), LEFT(), RIGHT(), LPAD(), RPAD(), and REPEAT() functions, a missing
NULL value check was corrected.
• For the LIKE operator, an attempt to use an uninitialized string buffer in the case of an empty wildcard
was corrected.
240
MySQL 5.6 Release Notes
(Bug #12634989, Bug #59851, Bug #11766684)
• For debug builds, a field-type check raised an assertion if the type was MYSQL_TYPE_NULL. (Bug
#12620084)
• With index condition pushdown enabled, a crash could occur due to an invalid end-of-range value. (Bug
#12601961)
• The option-parsing code for empty strings leaked memory. (Bug #12589928)
• The server could fail to free allocated memory when INSERT DELAYED was used with binary logging
enabled. (Bug #12538873)
• A DBUG_ASSERT added by Bug #11792200 was overly aggressive in raising assertions. (Bug
#12537160)
References: See also: Bug #11792200.
• In some cases, memory allocated for Query_tables_list::sroutines() was not freed properly.
(Bug #12429877)
• After the fix for Bug #11889186, MAKEDATE() arguments with a year part greater than 9999 raised an
assertion. (Bug #12403504)
References: This issue is a regression of: Bug #11889186.
• An assertion could be raised due to a missing NULL value check in
Item_func_round::fix_length_and_dec(). (Bug #12392636)
• Assignments to NEW.var_name within triggers, where var_name had a BLOB or TEXT type, were not
properly handled and produced incorrect results. (Bug #12362125)
• An assertion could be raised if Index Condition Pushdown code pushed down an index condition
containing a subquery. (Bug #12355958)
• XA COMMIT could fail to clean up the error state if it discovered that the current XA transaction had to be
rolled back. Consequently, the next XA transaction could raise an assertion when it checked for proper
cleanup of the previous transaction. (Bug #12352846)
• An assertion could be raised during two-phase commits if the binary log was used as the transaction
coordinator log. (Bug #12346411)
• InnoDB could add temporary index information to INFORMATION_SCHEMA, which could raise an
assertion. (Bug #12340873)
• mysql_list_fields() returned incorrect character set information for character columns of views.
(Bug #12337762)
• A too-strict assertion could cause a server crash. (Bug #12321461)
• mysql_upgrade did not properly upgrade the authentication_string column of the mysql.user
table. (Bug #11936829)
• The optimizer sometimes chose a forward index scan followed by a filesort to reverse the order rather
than scanning the index in reverse order. (Bug #11882131)
• Previously, an inappropriate error message was produced if a multiple-table update for an InnoDB
table with a clustered primary key would update a table through multiple aliases, and perform an update
241
MySQL 5.6 Release Notes
that may physically move the row in at least one of these aliases. Now the error message is: Primary
key/partition key update is not permitted since the table is updated both as
'tbl_name1' and 'tbl_name2' (Bug #11882110)
References: See also: Bug #11764529.
• With index condition pushdown enabled, queries that used STRAIGHT_JOIN on data that included NULL
values could return incorrect results. (Bug #11873324)
• InnoDB invoked some zlib functions without proper initialization. (Bug #11849231)
• Division of large numbers could cause stack corruption. (Bug #11792200)
• Corrected a condition that produced an InnoDB message in the error log, unlock row could not
find a 3 mode lock on the record. This situation could occur with a combination of a subquery
and a FOR UPDATE clause under the READ UNCOMMITTED isolation level. The fix also improves the
debuggability of such messages by including the original SQL statements that caused them. (Bug
#11766322, Bug #59410)
• With Valgrind enabled, InnoDB semaphore wait timeouts were too low and could expire. (Bug
#11765460)
• CHECK TABLE and REPAIR TABLE failed to find problems with MERGE tables that had underlying tables
missing or with the wrong storage engine. Issues were reported only for the first underlying table. (Bug
#11754210)
• (5 DIV 2) and (5.0 DIV 2) produced different results (2 versus 3) because the result of the latter
expression was not truncated before conversion to integer. This differed from the behavior in MySQL 5.0
and 5.1. Now both expressions produce 2. (Bug #61676, Bug #12711164)
• The server failed to compile if partitioning support was disabled. (Bug #61625, Bug #12694147)
• ALTER TABLE {MODIFY|CHANGE} ... FIRST did nothing except rename columns if the old and new
versions of the table had exactly the same structure with respect to column data types. As a result, the
mapping of column name to column data was incorrect. The same thing happened for ALTER TABLE
DROP COLUMN ... ADD COLUMN statements intended to produce a new version of the table with
exactly the same structure as the old version. (Bug #61493, Bug #12652385)
• Incorrect handling of metadata locking for FLUSH TABLES WITH READ LOCK for statements requiring
prelocking caused two problems:
• Execution of any data-changing statement that required prelocking (that is, involved a stored
function or trigger) as part of a transaction slowed down somewhat all subsequent statements in
the transaction. Performance in a transaction that periodically involved such statements gradually
degraded over time.
• Execution of any data-changing statement that required prelocking as part of a transaction prevented
a concurrent FLUSH TABLES WITH READ LOCK from proceeding until the end of the transaction
rather than at the end of the particular statement.
(Bug #61401, Bug #12641342)
• A problem introduced in MySQL 5.5.11 caused very old (MySQL 4.0) clients to be unable to connect to
the server. (Bug #61222, Bug #12563279)
• The fractional part of the “Queries per second” value could be displayed incorrectly in MySQL status
output (for example, in the output from mysqladmin status or the mysql STATUS command). (Bug
#61205, Bug #12565712)
242
MySQL 5.6 Release Notes
• The mysql-log-rotate script was updated because it referred to deprecated MySQL options. (Bug
#61038, Bug #12546842)
• Using CREATE EVENT IF NOT EXISTS for an event that already existed and was enabled caused
multiple instances of the event to run. (Bug #61005, Bug #12546938)
• If a statement ended with mismatched quotes, the server accepted the statement and interpreted
whatever was after the initial quote as a text string. (Bug #60993, Bug #12546960)
• LOAD DATA INFILE incorrectly parsed relative data file path names that ascended more than
three levels in the file system and as a consequence was unable to find the file. (Bug #60987, Bug
#12403662)
• Fixed “shift count greater than width of type” compilation warnings. (Bug #60908, Bug #12402772)
References: See also: Bug #12561303.
• Table I/O for the table_io_waits_summary_by_index_usage Performance Schema table was
counted as using no index for UPDATE and DELETE statements, even when an index was used. (Bug
#60905, Bug #12370950)
• An internal client macro reference was removed from the client_plugin.h header file. This reference
made the file unusable. (Bug #60746, Bug #12325444)
• Comparison of a DATETIME stored program variable and NOW() resulted in “Illegal mix of collations
error” when character_set_connection was set to utf8. (Bug #60625, Bug #11926811)
• Selecting from a view for which the definition included a HAVING clause failed with an error:
1356: View '...' references invalid table(s) or column(s)
or function(s) or definer/invoker of view lack rights to use them
(Bug #60295, Bug #11829681)
• CREATE TABLE syntax permits specification of a STORAGE {DEFAULT|DISK|MEMORY} option.
However, this value was not written to the .frm file, so that a subsequent CREATE TABLE ... LIKE
for the table did not include that option.
Also, ALTER TABLE of a table that had a tablespace incorrectly destroyed the tablespace. (Bug #60111,
Bug #11766883, Bug #34047, Bug #11747789)
• The mysql_load_plugin() C API function did not clear the previous error. (Bug #60075, Bug
#11766854)
• For repeated invocation of some stored procedures, the server consumed memory that it did not release
until the connection terminated. (Bug #60025, Bug #11848763)
• The server permitted max_allowed_packet to be set lower than net_buffer_length, which does
not make sense because max_allowed_packet is the upper limit on net_buffer_length values.
Now a warning occurs and the value remains unchanged. (Bug #59959, Bug #11766769)
• The server did not check for certain invalid out of order sequences of XA statements, and these
sequences raised an assertion. (Bug #59936, Bug #11766752, Bug #12348348)
• Index condition pushdown code accessed an uninitialized variable. (Bug #59843, Bug #11766678)
• For unknown users, the native password plugin reported incorrectly that no password had been specified
even when it had. (Bug #59792, Bug #11766641)
243
MySQL 5.6 Release Notes
• SELECT DISTINCT with a deterministic stored function in the WHERE clause could produce incorrect
results. (Bug #59736, Bug #11766594)
• Setting optimizer_join_cache_level to 3 or greater raised an assertion for some queries. (Bug
#59651, Bug #11766522)
• Previously, Performance Schema table columns that held byte counts were BIGINT UNSIGNED. These
were changed to BIGINT (signed). This makes it easier to perform calculations that compute differences
between columns. (Bug #59631, Bug #11766504)
• A missing variable initialization for Item_func_set_user_var objects could raise an assertion. (Bug
#59527, Bug #11766424)
• For some queries, the optimizer performed range analysis too many times for the same index. (Bug
#59415, Bug #11766327)
• With the conversion from GNU autotools to CMake for configuring MySQL, the USE_SYMDIR
preprocessor symbol was omitted. This caused failure of symbolic links (described at Using Symbolic
Links). (Bug #59408, Bug #11766320)
• An incorrect max_length value for YEAR values could be used in temporary result tables for UNION,
leading to incorrect results. (Bug #59343, Bug #11766270)
• In Item_func_in::fix_length_and_dec(), a Valgrind warning for uninitialized values was
corrected. (Bug #59270, Bug #11766212)
• An invalid pathname argument for the --defaults-extra-file option of MySQL programs caused a
program crash. (Bug #59234, Bug #11766184)
• In Item_func_month::val_str(), a Valgrind warning for a too-late NULL value check was
corrected. (Bug #59166, Bug #11766126)
• In Item::get_date, a Valgrind warning for a missing NULL value check was corrected. (Bug #59164,
Bug #11766124)
• In extract_date_time(), a Valgrind warning for a missing end-of-string check was corrected. (Bug
#59151, Bug #11766112)
• Some tables were not instrumented by the Performance Schema even though they were listed in the
setup_objects table. (Bug #59150, Bug #11766111)
• In string context, the MIN() and MAX() functions did not take into account the unsignedness of a
BIGINT UNSIGNED argument. (Bug #59132, Bug #11766094)
• In Item_func::val_decimal, a Valgrind warning for a missing NULL value check was corrected.
(Bug #59125, Bug #11766087)
• In ROUND() calculations, a Valgrind warning for uninitialized memory was corrected. (Bug #58937, Bug
#11765923)
References: This issue is a regression of: Bug #33143.
• The range created by the optimizer when OR-ing two conditions could be incorrect, causing incorrect
query results. (Bug #58834, Bug #11765831)
• Valgrind warnings caused by comparing index values to an uninitialized field were corrected. (Bug
#58705, Bug #11765713)
244
MySQL 5.6 Release Notes
• As a side effect of optimizing condition AND TRUE or condition OR FALSE, MySQL for certain
subqueries forgot that the columns used by the condition needed to be read, which raised an assertion in
debug builds. (Bug #58690, Bug #11765699)
• CREATE TRIGGER and DROP TRIGGER can change the prelocking list of stored routines, but the routine
cache did not detect such changes, resulting in routine execution with an inaccurate locking list. (Bug
#58674, Bug #11765684)
• In Item_func_str_to_date::val_str, a Valgrind warning for an uninitialized variable was
corrected. (Bug #58154, Bug #11765216)
• The code for PROCEDURE ANALYSE() had a missing DBUG_RETURN statement, which could cause a
server crash in debug builds. (Bug #58140, Bug #11765202)
• LOAD DATA INFILE errors could leak I/O cache memory. (Bug #58072, Bug #11765141)
• For LOAD DATA INFILE, multibyte character sequences could be pushed onto a stack too small to
accommodate them. (Bug #58069, Bug #11765139)
• The embedded server crashed when argc = 0. (Bug #57931, Bug #12561297)
• An assertion could be raised in Item_func_int_val::fix_num_length_and_dec() due to
overflow for geometry functions. (Bug #57900, Bug #11764994)
• An assertion was raised if a statement tried to upgrade a metadata lock while there was an active FLUSH
TABLE tbl_list WITH READ LOCK statement. Now if a statement tries to upgrade a metadata lock
in this situation, the server returns an ER_TABLE_NOT_LOCKED_FOR_WRITE error to the client. (Bug
#57649, Bug #11764779)
• The optimizer sometimes requested ordered access from a storage engine when ordered access was
not required. (Bug #57601, Bug #11764737)
• An embedded client aborted rather than issuing an error message if it issued a TEE command (\T
file_name) and the directory containing the file did not exist. This occurred because the wrong error
handler was called. (Bug #57491, Bug #11764633)
• ALTER EVENT could change the event status. (Bug #57156, Bug #11764334)
• For an outer join with a NOT IN subquery in the WHERE clause, a null left operand to the NOT IN
returned was treated differently than a literal NULL operand. (Bug #56881, Bug #11764086)
• Threads blocked in the waiting for table metadata state were not visible in
performance_schema.THREADS or SHOW PROFILE. (Bug #56475, Bug #11763728)
• With prepared statements, the server could attempt to send result set metadata after the table had been
closed. (Bug #56115, Bug #11763413)
• Table objects associated with one session's optimizer structures could be closed after being passed
to another session, prematurely ending the second session's table or index scan. (Bug #56080, Bug
#11763382)
• In some cases, SHOW WARNINGS returned an empty result when the previous statement failed. (Bug
#55847, Bug #11763166)
• A handled condition (error or warning) could be shown as not handled at the end of the statement. (Bug
#55843, Bug #11763162)
References: This issue is a regression of: Bug #23032.
245
MySQL 5.6 Release Notes
• In debug builds, Field_new_decimal::store_value() was subject to buffer overflows. (Bug
#55436, Bug #11762799)
• For an InnoDB table, dropping and adding an index in a single ALTER TABLE statement could fail. (Bug
#54927, Bug #11762345)
• For a client connected using SSL, the Ssl_cipher_list status variable was empty and did not show
the possible cipher types. (Bug #52596, Bug #11760210)
• The mysql client sometimes did not properly close sessions terminated by the user with Control+C.
(Bug #52515, Bug #11760134)
• CREATE TABLE ... LIKE for a MyISAM table definition that included an DATA DIRECTORY or INDEX
DIRECTORY table option failed, instead of creating a table with those options omitted as documented.
(Bug #52354, Bug #11759990)
• Spatial operations on certain corner cases could cause a server crash: Polygons with zero-point
linerings; polygons with touching linerings. (Bug #51979, Bug #11759650, Bug #47429, Bug #11755628)
• Attempts to grant the EXECUTE or ALTER ROUTINE privilege for a nonexistent stored procedure
returned success instead of an error. (Bug #51401, Bug #11759114)
• With lower_case_table_names=2, resolution of objects qualified by database names could fail. (Bug
#50924, Bug #11758687)
• CREATE TABLE without an ENGINE option determined the default engine at parse rather than execution
time. This led to incorrect results if the statement was executed within a stored program and the default
engine had been changed in the meantime. (Bug #50614, Bug #11758414)
• On Linux, the mysql client built using the bundled libedit did not read ~/.editrc. (Bug #49967,
Bug #11757855)
• For some statements such as DESCRIBE or SHOW, views with too many columns produced errors. (Bug
#49437, Bug #11757397)
• The optimizer sometimes incorrectly processed HAVING clauses for queries that did not also have an
ORDER BY clause. (Bug #48916, Bug #11756928)
• PROCEDURE ANALYSE() could leak memory for NULL results, and could return incorrect results if used
with a LIMIT clause. (Bug #48137, Bug #11756242)
• A race condition between loading a stored routine using the name qualified by the database name
and dropping that database resulted in a spurious error message: The table mysql.proc is
missing, corrupt, or contains bad data (Bug #47870, Bug #11756013)
• When used to upgrade tables, mysqlcheck (and mysql_upgrade, which invokes mysqlcheck)
did not upgrade some tables for which table repair was found to be necessary. In particular, it failed
to upgrade InnoDB tables that needed repair, leaving them in a nonupgraded state. This occurred
because:
• mysqlcheck --check-upgrade ---auto-repair checks for tables that are incompatible
with the current version of MySQL. It does this by issuing the CHECK TABLE ... FOR UPGRADE
statement and examining the result.
• For any table found to be incompatible, mysqlcheck issues a REPAIR TABLE statement. But this
fails for storage engines such as InnoDB that do not support the repair operation. Consequently, the
table remained unchanged.
246
MySQL 5.6 Release Notes
To fix the problem, the following changes were made to CHECK TABLE ... FOR UPGRADE and
mysqlcheck. Because mysql_upgrade invokes mysqlcheck, these changes also fix the problem for
mysql_upgrade.
• CHECK TABLE ... FOR UPGRADE returns a different error if a table needs repair but its storage
engine does not support REPAIR TABLE:
Previous:
Error: ER_TABLE_NEEDS_UPGRADE
Table upgrade required. Please do "REPAIR TABLE `tbl_name`" or
dump/reload to fix it!
Now:
Error: ER_TABLE_NEEDS_REBUILD
Table rebuild required. Please do "ALTER TABLE `tbl_name` FORCE" or
dump/reload to fix it!
• mysqlcheck recognizes the new error and issues an ALTER TABLE ... FORCE statement. The
FORCE option for ALTER TABLE was recognized but did nothing; now it is implemented and acts as a
“null” alter operation that rebuilds the table.
(Bug #47205, Bug #11755431)
• On some platforms, the Incorrect value: xxx for column yyy at row zzz error produced
by LOAD DATA INFILE could have an incorrect value of zzz. (Bug #46895, Bug #11755168)
• Upgrades using an RPM package recreated the test database, which is undesirable when the DBA had
removed it. (Bug #45415, Bug #11753896)
• In MySQL 5.1 and up, if a table had triggers that used syntax supported in 5.0 but not 5.1, the table
became unavailable. Now the table is marked as having broken triggers. These should be dropped and
recreated manually. (Bug #45235, Bug #11753738)
• An attempt to install nonexistent files during installation was corrected. (Bug #43247, Bug #11752142)
• Some status variables rolled over to zero after reaching the maximum 32-bit value. They have been
changed to 64-bit values. (Bug #42698, Bug #11751727)
• SHOW EVENTS did not always show events from the correct database. (Bug #41907, Bug #11751148)
• For queries with many eq_ref joins, the optimizer took excessive time to develop an execution plan.
(Bug #41740, Bug #11751026, Bug #58225, Bug #11765274)
• On FreeBSD 64-bit builds of the embedded server, exceptions were not prevented from propagating into
the embedded application. (Bug #38965, Bug #11749418)
• With DISTINCT, CONCAT(col_name,...) returned incorrect results when the arguments to
CONCAT() were columns with an integer data type declared with a display width narrower than the
values in the column. (For example, if an INT(1) column contained 1111.) (Bug #4082)
247
MySQL 5.6 Release Notes
Changes in MySQL 5.6.2 (2011-04-11, Developer Milestone)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
• INFORMATION_SCHEMA Tables for InnoDB Buffer Pool Information
• INFORMATION_SCHEMA Table for InnoDB Metrics
• INFORMATION_SCHEMA Tables for InnoDB Data Dictionary
• Persistent InnoDB Optimizer Statistics
• InnoDB Configurable Data Dictionary Cache
• Optimizer Notes
• Explicit Partition Selection
• Performance Schema Notes
• Pluggable Authentication
• Crash-Safe Binary Log
• Slave Log Tables
• Row Image Control
• Functionality Added or Changed
• Bugs Fixed
INFORMATION_SCHEMA Tables for InnoDB Buffer Pool Information
• InnoDB: The new INFORMATION_SCHEMA tables INNODB_BUFFER_PAGE,
INNODB_BUFFER_PAGE_LRU, and INNODB_BUFFER_POOL_STATS display InnoDB buffer pool
information for tuning on large-memory or highly loaded systems.
INFORMATION_SCHEMA Table for InnoDB Metrics
• InnoDB: A new INFORMATION_SCHEMA table, INNODB_METRICS, lets you query low-level InnoDB
performance information, getting cumulative counts, averages, and minimum/maximum values for
internal aspects of the storage engine operation. You can start, stop, and reset the metrics counters
using the innodb_monitor_enable, innodb_monitor_disable, innodb_monitor_reset, and
innodb_monitor_reset_all system variables.
INFORMATION_SCHEMA Tables for InnoDB Data Dictionary
• InnoDB: The InnoDB data dictionary, containing metadata about InnoDB tables, columns, indexes, and
foreign keys, is available for SQL queries through a set of INFORMATION_SCHEMA tables.
Persistent InnoDB Optimizer Statistics
248
MySQL 5.6 Release Notes
• Performance; InnoDB: The optimizer statistics for InnoDB tables can now persist across server
restarts, producing more stable query performance. You can also control the amount of sampling
done to estimate cardinality for each index, resulting in more accurate optimizer statistics. This
feature involves the configuration options innodb_analyze_is_persistent (later replaced
by innodb_stats_persistent), innodb_stats_persistent_sample_pages, and
innodb_stats_transient_sample_pages, and the ANALYZE TABLE statement. See Configuring
Persistent Optimizer Statistics Parameters for details.
InnoDB Configurable Data Dictionary Cache
• InnoDB: To ease the memory load on systems with huge numbers of tables, InnoDB now frees up
the memory associated with an opened table using an LRU algorithm to select tables that have gone
the longest without being accessed. To reserve more memory to hold metadata for open InnoDB
tables, increase the value of the table_definition_cache configuration option. InnoDB treats
this value as a “soft limit” for the number of open table instances in the InnoDB data dictionary
cache. The actual number of tables with cached metadata could be higher than the value specified
for table_definition_cache, because metadata for InnoDB system tables, and parent and child
tables in foreign key relationships, is never evicted from memory. For additional information, refer to the
table_definition_cache documentation. (Bug #20877, Bug #11745884)
Optimizer Notes
• The optimizer now more efficiently handles queries (and subqueries) of the following form:
SELECT ...
FROM single_table ...
ORDER BY non_index_column [DESC]
LIMIT [M,]N;
That type of query is common in web applications that display only a few rows from a larger result set.
For example:
SELECT col1, ... FROM t1 ... ORDER BY name LIMIT 10;
SELECT col1, ... FROM t1 ... ORDER BY RAND() LIMIT 15;
The sort buffer has a size of sort_buffer_size. If the sort elements for N rows are small enough to fit
in the sort buffer (M+N rows if M was specified), the server can avoid using a merge file and perform the
sort entirely in memory. For details, see LIMIT Query Optimization.
• The optimizer implements Disk-Sweep Multi-Range Read. Reading rows using a range scan on a
secondary index can result in many random disk accesses to the base table when the table is large and
not stored in the storage engine's cache. With the Disk-Sweep Multi-Range Read (MRR) optimization,
MySQL tries to reduce the number of random disk access for range scans by first scanning the index
only and collecting the keys for the relevant rows. Then the keys are sorted and finally the rows are
retrieved from the base table using the order of the primary key. The motivation for Disk-sweep MRR is
to reduce the number of random disk accesses and instead achieve a more sequential scan of the base
table data. For more information, see Multi-Range Read Optimization.
• The optimizer implements Index Condition Pushdown (ICP), an optimization for the case where MySQL
retrieves rows from a table using an index. Without ICP, the storage engine traverses the index to locate
rows in the base table and returns them to the MySQL server which evaluates the WHERE condition for
the rows. With ICP enabled, and if parts of the WHERE condition can be evaluated by using only fields
from the index, the MySQL server pushes this part of the WHERE condition down to the storage engine.
The storage engine then evaluates the pushed index condition by using the index entry and only if this
is satisfied is base row be read. ICP can reduce the number of accesses the storage engine has to do
249
MySQL 5.6 Release Notes
against the base table and the number of accesses the MySQL server has to do against the storage
engine. For more information, see Index Condition Pushdown Optimization.
Explicit Partition Selection
• Partitioning: It is now possible to select one or more partitions or subpartitions when querying a
partitioned table. In addition, many data modification statements (DELETE, INSERT, REPLACE, UPDATE,
LOAD DATA, and LOAD XML) that act on partitioned tables also now support explicit partition selection.
For example, assume we have a table named t with some integer column named c, and t has 4
partitions named p0, p1, p2, and p3. Then the query SELECT * FROM t PARTITION (p0, p1)
WHERE c < 5 returns rows only in partitions p0 and p1 that match the WHERE condition, whereas
partitions p2 and p3 are not checked.
For additional information and examples, see Partition Selection, as well as the descriptions of the
statements just listed.
Performance Schema Notes
• The Performance Schema has these additions:
• The Performance Schema now has tables that contain summaries for table and index I/O wait events,
as generated by the wait/io/table/sql/handler instrument:
• table_io_waits_summary_by_table: Aggregates table I/O wait events. The grouping is by
table.
• table_io_waits_summary_by_index_usage: Aggregates table index I/O wait events. The
grouping is by table index.
The information in these tables can be used to assess the impact of table I/O performed by
applications. For example, it is possible to see which tables are used and which indexes are used (or
not used), or to identify bottlenecks on a table when multiple applications access it. The results may be
useful to change how applications issue queries against a database, to minimize application footprint
on the server and to improve application performance and scalability.
A change that accompanies the new tables is that the events_waits_current table now
has an INDEX_NAME column to identify which index was used for the operation that generated
the event. The same is true of the event-history tables, events_waits_history, and
events_waits_history_long.
• The Performance Schema now has an instrument named wait/lock/table/sql/handler in the
setup_instruments table for instrumenting table lock wait events. It differs from wait/io/table/
sql/handler, which instruments table I/O. This enables independent instrumentation of table I/O
and table locks.
Accompanying the new instrument, the Performance Schema has a table named
table_lock_waits_summary_by_table that aggregates table lock wait events, as generated by
the new instrument. The grouping is by table.
The information in this table may be used to assess the impact of table locking performed by
applications. The results may be useful to change how applications issue queries against the database
and use table locks, to minimize the application footprint on the server and to improve application
performance and scalability. For example, an application locking tables for a long time may negatively
affect other applications; the instrumentation makes this visible.
• To selectively control which tables to instrument for I/O and locking, use the setup_objects table.
See Pre-Filtering by Object.
250
MySQL 5.6 Release Notes
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the performance_schema database.
For more information, see MySQL Performance Schema.
Pluggable Authentication
• MySQL distributions now include auth_socket, a server-side authentication plugin that authenticates
clients that connect from the local host through the Unix socket file. The plugin uses the SO_PEERCRED
socket option to obtain information about the user running the client program (and thus can be built
only on systems that support this option). For a connection to succeed, the plugin requires a match
between the login name of the connecting client user and the MySQL user name presented by the client
program. For more information, see Socket Peer-Credential Pluggable Authentication. (Bug #59017, Bug
#11765993, Bug #9411, Bug #11745104)
• MySQL distributions now include mysql_clear_password, a client-side authentication plugin that
sends the password to the server without hashing or encryption. Although this is insecure, and thus
appropriate precautions should be taken (such as using an SSL connection), the plugin is useful in
conjunction with server-side plugins that must have access to the original password in clear text. For
more information, see Client-Side Cleartext Pluggable Authentication.
Crash-Safe Binary Log
• Replication: Support for checksums when writing and reading the binary log is added to the MySQL
Server. Writing checksums into the binary log is disabled by default; it can be enabled by starting the
server with the --binlog-checksum option. To cause the server to read checksums from the binary
log, start the server with the --master-verify-checksum option. The --slave-sql-verifychecksum option causes the slave to read checksums from the relay log.
• Replication: The MySQL Server now records and reads back only complete events or transactions to
and from the binary log. By default, the server now logs the length of the event as well as the event itself
and uses this information to verify that the event was written correctly to the log. A master also uses by
default this value to verify events when reading from the binary log.
If you enable writing of checksums (using the binlog_checksum system variable), the master can
use these instead by enabling the master_verify_checksum system variable. The slave I/O thread
also verifies events received from the master. You can cause the slave SQL thread to use checksums
(if available) as well, when reading from the relay log, by enabling the slave_sql_verify_checksum
system variable on the slave.
Slave Log Tables
• Replication: It is now possible to write information about the slave connection to the master and about
the slave's execution point within the relay log to tables rather than files. Logging of master connection
information and of slave relay log information to tables can be done independently of one another; this
is controlled by the --master-info-repository and --relay-log-info-repository server
options. When --master-info-repository is set to TABLE, connection information is logged in the
slave_master_info table in the mysql system database. When --relay-log-info-repository
is set to TABLE, relay log information is logged to the slave_relay_log_info table, also in the
mysql database.
Row Image Control
• Replication: Added the binlog_row_image server system variable, which can be used to enable row
image control for row-based replication. This means that you can potentially save disk space, network
251
MySQL 5.6 Release Notes
resources, and memory usage by the MySQL Server by logging only those columns that are required for
uniquely identifying rows, or which are actually changed on each row, as opposed to logging all columns
for each and every row change event. In addition, you can use a “noblob” mode where all columns,
except for unneeded BLOB or TEXT columns, are logged.
For more information, see System Variables Used with Binary Logging. (Bug #47200, Bug #47303, Bug
#56917, Bug #11755426, Bug #11755513, Bug #11764116)
Functionality Added or Changed
• Incompatible Change: The following obsolete constructs have been removed. Where alternatives are
shown, applications should be updated to use them.
• The FLUSH MASTER and FLUSH SLAVE statements. Use the RESET MASTER and RESET SLAVE
statements instead.
• Important Change; Replication: Added the --binlog-rows-query-log-events option for
mysqld. Using this option causes a server logging in row-based mode to write informational rows query
log events (SQL statements, for debugging and other purposes) to the binary log. MySQL server and
MySQL programs from MySQL 5.6.2 and later normally ignore such events, so that they do not pose
an issue when reading the binary log. mysqld and mysqlbinlog from previous MySQL releases
cannot read such events in the binary log, and fail if they attempt to do so. For this reason, you should
never prepare logs for a MySQL 5.6.1 or earlier replication slave server (or other reader such as
mysqlbinlog) with this option enabled on the master. (Bug #50935, Bug #11758695)
• Performance; InnoDB: A separate InnoDB thread (page_cleaner) now handles the flushing of dirty
pages that was formerly done by the InnoDB master thread. (Bug #11762412, Bug #55004)
• Performance; InnoDB: The innodb_purge_threads system variable can now be set to a value
higher than 1.
• Performance; InnoDB: The InnoDB kernel mutex, which controls concurrent access to the InnoDB
kernel, has been split into several mutexes and rw-locks, for improved concurrency.
• InnoDB: InnoDB can optionally log details about all deadlocks that occur, to assist with troubleshooting
and diagnosis. This feature is controlled by the innodb_print_all_deadlocks system variable. (Bug
#1784, Bug #17572)
• Replication: On MySQL replication slaves having multiple network interfaces, it is now possible to set
which interface to use for connecting to the master using the MASTER_BIND='interface' option in a
CHANGE MASTER TO statement.
The value set by this option can be seen in the Master_Bind column of the output from SHOW SLAVE
STATUS or the Bind column of the mysql.slave_master_info table. (Bug #25939, Bug #11746389)
• Replication: Added the log_bin_basename system variable, which contains the complete file name
and path to the binary log file. (The log_bin system variable shows only whether or not binary logging
is enabled; log_bin_basename, however, reflects the name set with the --log-bin server option.)
Also added relay_log_basename system variable, which shows the file name and complete path to
the relay log file.
References: See also: Bug #19614, Bug #11745759.
• The mysql_upgrade, mysqlbinlog, mysqlcheck, mysqlimport, mysqlshow, and mysqlslap
clients now have --default-auth and --plugin-dir options for specifying which authentication
plugin and plugin directory to use. (Bug #58139)
252
MySQL 5.6 Release Notes
• The server now includes the thread ID in rows written to the slow query log. In the slow query log file,
the thread ID is the last value in the line. In the mysql.slow_log log table, there is a new thread_id
column.
To update the slow_log table if you are upgrading from an earlier release, run mysql_upgrade and
restart the server. See mysql_upgrade — Check and Upgrade MySQL Tables. (Bug #53630, Bug
#11761166)
• The server now writes thread shutdown messages to the error log during the shutdown procedure. (Bug
#48388, Bug #11756464)
• If the --init-file option is given, the server now writes messages indicating the beginning and end of
file execution to the error log. (Bug #48387, Bug #11756463)
• Boolean system variables can be enabled at run time by setting them to the value ON or OFF, but
previously this did not work at server startup. Now at startup such variables can be enabled by setting
them to ON or TRUE, or disabled by setting them to OFF or FALSE. Any other nonnumeric value is invalid.
(Bug #46393)
References: See also: Bug #11754743, Bug #51631.
• MySQL distributions now include an INFO_SRC file that contains information about the source
distribution, such as the MySQL version from which it was created. MySQL binary distributions
additionally include an INFO_BIN file that contains information about how the distribution was built, such
as compiler options and feature flags. In RPM packages, these files are located in the /usr/share/
doc/packages/MySQL-server directory. In tar.gz and derived packages, they are located in the
Docs directory under the location where the distribution is unpacked. (Bug #42969, Bug #11751935)
• Multi-read range access is now based on cost estimates and no longer used for simple queries for which
it is not beneficial. (Bug #37576, Bug #11748865)
• Previously, for queries that were aborted due to a sort problem, the server wrote the message Sort
aborted to the error log. Now the server writes more information to provide a more specific message,
such as:
Sort aborted: Out of memory (Needed 24 bytes)
Out of sort memory, consider increasing server sort buffer size
Sort aborted: Out of sort memory, consider increasing server sort
buffer size
Sort aborted: Incorrect number of arguments for FUNCTION test.f1;
expected 0, got 1
In addition, if the server was started with --log-warnings=2, the server writes information about the
host, user, and query. (Bug #36022, Bug #11748358)
• Previously, for queries that were aborted due to a sort problem or terminated with KILL in the middle
of a sort, the server wrote the message Sort aborted to the error log. Now the server writes more
information about the cause of the error. These causes include:
• Insufficient disk space in the temporary file directory prevented a temp file from being created
• Insufficient memory for sort_buffer_size to be allocated
• Somebody ran KILL id in the middle of a filesort operation
• The server was shut down while some queries were sorting
• A transaction was rolled back or aborted due to a lock wait timeout or deadlock
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MySQL 5.6 Release Notes
• Unexpected errors, such as a source table or even temp table was corrupt
• Processing of a subquery failed which was also sorting
(Bug #30771, Bug #11747102)
• mysqldump --xml now displays comments from column definitions. (Bug #13618, Bug #11745324)
• Windows provides APIs based on UTF-16LE for reading from and writing to the console. MySQL now
supports a utf16le character set for UTF-16LE, and the mysql client for Windows has been modified
to provide improved Unicode support by using these APIs.
To take advantage of this change, you must run mysql within a console that uses a compatible Unicode
font and set the default character set to a Unicode character set that is supported for communication with
the server. For instructions, see Unicode Support on Windows.
• The undocumented SHOW NEW MASTER statement has been removed.
• A new plugin service, my_plugin_log_service, enables plugins to report errors and specify error
messages. The server writes the messages to the error log. See MySQL Services for Plugins.
Bugs Fixed
• Security Fix: Pre-evaluation of LIKE predicates during view preparation could cause a server crash.
(Bug #54568, Bug #11762026, CVE-2010-3836)
• Incompatible Change; Replication: It is no longer possible to issue a CREATE TABLE ... SELECT
statement which changes any tables other than the table being created. Any such statement is not
executed and instead fails with an error.
One consequence of this change is that FOR UPDATE may no longer be used at all with the SELECT
portion of a CREATE TABLE ... SELECT.
This means that, prior to upgrading from a previous release, you should rewrite any CREATE
TABLE ... SELECT statements that cause changes in other tables so that the statements no longer do
so.
This change also has implications for statement-based replication between a MySQL 5.6 (or later slave)
and a master running a previous version of MySQL. In such a case, if a CREATE TABLE ... SELECT
statement on the master that causes changes in other tables succeeds on the master, the statement
nonetheless fails on the slave, causing replication to stop. To keep this from happening, you should
either use row-based replication, or rewrite the offending statement before running it on the master. (Bug
#11749792, Bug #11745361, Bug #39804, Bug #55876)
References: See also: Bug #47899.
• Incompatible Change: When auto_increment_increment is greater than one, values generated by
a bulk insert that reaches the maximum column value could wrap around rather producing an overflow
error.
As a consequence of the fix, it is no longer possible for an auto-generated value to be equal to the
maximum BIGINT UNSIGNED value. It is still possible to store that value manually, if the column can
accept it. (Bug #39828, Bug #11749800)
• Important Change; Partitioning: Date and time functions used as partitioning functions now have the
types of their operands checked; use of a value of the wrong type is now disallowed in such cases. In
addition, EXTRACT(WEEK FROM col_name), where col_name is a DATE or DATETIME column, is now
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MySQL 5.6 Release Notes
disallowed altogether because its return value depends on the value of the default_week_format
system variable. (Bug #54483, Bug #11761948)
References: See also: Bug #57071, Bug #11764255.
• Important Change; Replication: The CHANGE MASTER TO statement required the value for
RELAY_LOG_FILE to be an absolute path, whereas the MASTER_LOG_FILE path could be relative.
The inconsistent behavior is resolved by permitting relative paths for RELAY_LOG_FILE, in which case
the path is assumed to be relative to the slave's data directory. (Bug #12190, Bug #11745232)
• Performance; InnoDB: An UPDATE statement for an InnoDB table could be slower than necessary if it
changed a column covered by a prefix index, but did not change the prefix portion of the value. The fix
improves performance for InnoDB 1.1 in MySQL 5.5 and higher, and the InnoDB Plugin for MySQL 5.1.
(Bug #58912, Bug #11765900)
• InnoDB; Partitioning: The partitioning handler did not pass locking information to a table's storage
engine handler. This caused high contention and thus slower performance when working with partitioned
InnoDB tables. (Bug #59013)
• InnoDB: This fix introduces a new configuration option, innodb_change_buffer_max_size, which
defines the size of the change buffer as a percentage of the size of the buffer pool. Because the change
buffer shares memory space with the buffer pool, a workload with a high rate of DML operations could
cause pages accessed by queries to age out of the buffer pool sooner than desirable. This fix also
devotes more I/O capacity to flushing entries from the change buffer when it exceeds 1/2 of its maximum
size. (Bug #11766168, Bug #59214)
• InnoDB: The presence of a double quotation mark inside the COMMENT field for a column could prevent
a foreign key constraint from being created properly. (Bug #59197, Bug #11766154)
• InnoDB: It was not possible to query the information_schema.INNODB_TRX table while other
connections were running queries involving BLOB types. (Bug #55397, Bug #11762763)
• InnoDB: InnoDB returned values for “rows examined” in the query plan that were higher than expected.
NULL values were treated in an inconsistent way. The inaccurate statistics could trigger “false positives”
in combination with the max_join_size setting, because the queries did not really examine as many
rows as reported.
A new configuration option innodb_stats_method lets you specify how NULL values are treated
when calculating index statistics. Allowed values are nulls_equal (the default), nulls_unequal and
null_ignored. The meanings of these values are similar to those of the myisam_stats_method
option. (Bug #30423)
• Partitioning: Failed ALTER TABLE ... PARTITION statements could cause memory leaks. (Bug
#56380, Bug #11763641)
References: See also: Bug #46949, Bug #11755209, Bug #56996, Bug #11764187.
• Replication: When using the statement-based logging format, INSERT ON DUPLICATE KEY UPDATE
and INSERT IGNORE statements affecting transactional tables that did not fail were not written to the
binary log if they did not insert any rows. (With statement-based logging, all successful statements
should be logged, whether they do or do not cause any rows to be changed.) (Bug #59338, Bug
#11766266)
• Replication: Formerly, STOP SLAVE stopped the slave I/O thread first and then stopped the slave SQL
thread; thus, it was possible for the I/O thread to stop after replicating only part of a transaction which the
SQL thread was executing, in which case—if the transaction could not be rolled back safely—the SQL
thread could hang.
255
MySQL 5.6 Release Notes
Now, STOP SLAVE stops the slave SQL thread first and then stops the I/O thread; this guarantees
that the I/O thread can fetch any remaining events in the transaction that the SQL thread is executing,
so that the SQL thread can finish the transaction if it cannot be rolled back safely. (Bug #58546, Bug
#11765563)
• Replication: mysqlbinlog printed USE statements to its output only when the default database
changed between events. To illustrate how this could cause problems, suppose that a user issued the
following sequence of statements:
CREATE DATABASE mydb;
USE mydb;
CREATE TABLE mytable (column_definitions);
DROP DATABASE mydb;
CREATE DATABASE mydb;
USE mydb;
CREATE TABLE mytable (column_definitions);
When played back using mysqlbinlog, the second CREATE TABLE statement failed with Error: No
Database Selected because the second USE statement was not played back, due to the fact that a
database other than mydb was never selected.
This fix ensures that mysqlbinlog outputs a USE statement whenever it reads one from the binary log.
(Bug #50914, Bug #11758677)
• Replication: The --help text for mysqlbinlog now indicates that the --verbose (-v) option outputs
pseudo-SQL that is not necessarily valid SQL and cannot be guaranteed to work verbatim in MySQL
clients. (Bug #47557, Bug #11755743)
• Microsoft Windows: On Windows, an object in thread local storage could be used before the object
was created. (Bug #55730, Bug #11763065)
• Two unused test files in storage/ndb/test/sql contained incorrect versions of the GNU Lesser
General Public License. The files and the directory containing them have been removed. (Bug
#11810224)
References: See also: Bug #11810156.
• Queries that used COALESCE() with cp1251 strings could result in an “illegal mix of collations” error.
(Bug #60101, Bug #11766874)
• An assertion was raised if an XA COMMIT was issued when an XA transaction had already encountered
an error (such as a deadlock) that required the transaction to be rolled back. (Bug #59986, Bug
#11766788)
• On some systems, debug builds of comp_err could fail due to an uninitialized variable. (Bug #59906,
Bug #11766729)
• Setting the optimizer_switch system variable to an invalid value caused a server crash. (Bug
#59894, Bug #11766719)
• Attempting to create a spatial index on a CHAR column longer than 31 bytes led to an assertion failure if
the server was compiled with safemutex support. (Bug #59888, Bug #11766714)
• Aggregation followed by a subquery could produce an incorrect result. (Bug #59839, Bug #11766675)
• The Performance Schema did not update status handler status variables, so SHOW STATUS LIKE
'%handler%' produced undercounted values. (Bug #59799, Bug #11766645)
256
MySQL 5.6 Release Notes
• Internally, XOR items partially behaved like functions and partially as conditions. This resulted in
inconsistent handling and crashes. The issue is fixed by consistently treating XOR items as functions.
(Bug #59793, Bug #11766642)
• An incorrect character set pointer passed to my_strtoll10_mb2() caused an assertion to be raised.
(Bug #59648, Bug #11766519)
• DES_DECRYPT() could crash if the argument was not produced by DES_ENCRYPT(). (Bug #59632, Bug
#11766505)
• The server and client did not always properly negotiate authentication plugin names. (Bug #59453, Bug
#11766356)
• --autocommit=ON did not work (it set the global autocommit value to 0, not 1). (Bug #59432, Bug
#11766339)
• FIND_IN_SET() could work differently in MySQL 5.5 than in 5.1. (Bug #59405, Bug #11766317)
• mysqldump did not quote database names in ALTER DATABASE statements in its output, which could
cause an error at reload time for database names containing a dash. (Bug #59398, Bug #11766310)
• If filesort fell back to an ordinary sort/merge, it could fail to handle memory correctly. (Bug #59331,
Bug #11766260)
• Comparisons of aggregate values with TIMESTAMP values were incorrect. (Bug #59330, Bug
#11766259)
• The “greedy” query plan optimizer failed to consider the size of intermediate query results when
calculating the cost of a query. This could result in slowly executing queries when there are much faster
execution plans available. (Bug #59326, Bug #11766256)
• A query of the following form returned an incorrect result, where the values for col_name in the result
set were entirely replaced with NULL values:
SELECT DISTINCT col_name ... ORDER BY col_name DESC;
(Bug #59308, Bug #11766241)
• The MYSQL_HOME environment variable was being ignored. (Bug #59280, Bug #11766219)
• SHOW PRIVILEGES did not display a row for the PROXY privilege. (Bug #59275, Bug #11766216)
• SHOW PROFILE could truncate source file names or fail to show function names. (Bug #59273, Bug
#11766214)
• For DIV expressions, assignment of the result to multiple variables could cause a server crash. (Bug
#59241, Bug #11766191)
References: See also: Bug #8457.
• MIN(year_col) could return an incorrect result in some cases. (Bug #59211, Bug #11766165)
• With index condition pushdown enabled, a join could produce an extra row due to parts of the select
condition for the second table in the join not being evaluated. (Bug #59186, Bug #11766144)
• DELETE or UPDATE statements could fail if they used DATE or DATETIME values with a year, month, or
day part of zero. (Bug #59173)
257
MySQL 5.6 Release Notes
• The ESCAPE clause for the LIKE operator permits only expressions that evaluate to a constant at
execution time, but aggregate functions were not being rejected. (Bug #59149, Bug #11766110)
• Valgrind warnings about uninitialized variables were corrected. (Bug #59145, Bug #11766106)
• Memory leaks detected by Valgrind, some of which could cause incorrect query results, were corrected.
(Bug #59110, Bug #11766075)
• mysqlslap failed to check for a NULL return from mysql_store_result() and crashed trying to
process the result set. (Bug #59109, Bug #11766074)
• There was an erroneous restriction on file attributes for LOAD DATA INFILE. The requirement that a
file be located in the database directory or world readable is now that the be located in the database
directory or readable by the user account used to run the server. (Bug #59085, Bug #11766052)
• SHOW CREATE TRIGGER failed if there was a temporary table with the same name as the trigger subject
table. (Bug #58996, Bug #11765972)
• The DEFAULT_CHARSET and DEFAULT_COLLATION CMake options did not work. (Bug #58991, Bug
#11765967)
• In a subquery, a UNION with no referenced tables (or only a reference to the DUAL virtual table) did not
permit an ORDER BY clause. (Bug #58970, Bug #11765950)
• OPTIMIZE TABLE for an InnoDB table could raise an assertion if the operation failed because it had
been killed. (Bug #58933, Bug #11765920)
• If max_allowed_packet was set larger than 16MB, the server failed to reject too-large packets with
“Packet too large” errors. (Bug #58887, Bug #11765878)
• With index condition pushdown enabled, incorrect results were returned for queries on MyISAM tables
involving HAVING and LIMIT, when the column in the WHERE condition contained NULL. (Bug #58838,
Bug #11765835)
• An uninitialized variable for the index condition pushdown access method could result in a server crash
or Valgrind warnings. (Bug #58837, Bug #11765834)
• A NOT IN predicate with a subquery containing a HAVING clause could retrieve too many rows, when
the subquery itself returned NULL. (Bug #58818, Bug #11765815)
• Running a query against an InnoDB table twice, first with index condition pushdown enabled and then
with it disabled, could produce different results. (Bug #58816, Bug #11765813)
• An assertion was raised if a stored routine had a DELETE IGNORE statement that failed but due to the
IGNORE had not reported any error. (Bug #58709, Bug #11765717)
• WHERE conditions of the following forms were evaluated incorrectly and could return incorrect results:
WHERE null-valued-const-expression NOT IN (subquery)
WHERE null-valued-const-expression IN (subquery) IS UNKNOWN
(Bug #58628, Bug #11765642)
• Issuing EXPLAIN EXTENDED for a query that would use condition pushdown could cause mysqld to
crash. (Bug #58553, Bug #11765570)
• An OUTER JOIN query using WHERE col_name IS NULL could return an incorrect result. (Bug
#58490, Bug #11765513)
258
MySQL 5.6 Release Notes
• Starting the server with the --defaults-file=file_name option, where the file name had no
extension, caused a server crash. (Bug #58455, Bug #11765482)
• Outer joins with an empty table could produce incorrect results. (Bug #58422, Bug #11765451)
• In debug builds, SUBSTRING_INDEX(FORMAT(...), FORMAT(...)) could cause a server crash.
(Bug #58371, Bug #11765406)
• When mysqladmin was run with the --sleep and --count options, it went into an infinite loop
executing the specified command. (Bug #58221, Bug #11765270)
• Some string-manipulating SQL functions use a shared string object intended to contain an immutable
empty string. This object was used by the SQL function SUBSTRING_INDEX() to return an empty
string when one argument was of the wrong data type. If the string object was then modified by the SQL
function INSERT(), undefined behavior ensued. (Bug #58165, Bug #11765225)
• Condition pushdown optimization could push down conditions with incorrect column references. (Bug
#58134, Bug #11765196)
• injector::transaction did not have support for rollback. (Bug #58082, Bug #11765150)
• Parsing nested regular expressions could lead to recursion resulting in a stack overflow crash. (Bug
#58026, Bug #11765099)
• The fix for Bug #25192 caused load_defaults() to add an argument separator to distinguish options
loaded from option files from those provided on the command line, whether or not the application needed
it. (Bug #57953, Bug #11765041)
References: See also: Bug #25192, Bug #11746296.
• The mysql client went into an infinite loop if the standard input was a directory. (Bug #57450, Bug
#11764598)
• If a multiple-table update updated a row through two aliases and the first update physically moved
the row, the second update failed to locate the row. This resulted in different errors depending on the
storage engine, although these errors did not accurately describe the problem:
• MyISAM: Got error 134 from storage engine
• InnoDB: Can't find record in 'tbl'
For MyISAM, which is nontransactional, the update executed first was performed but the second was
not. In addition, for two equal multiple-table update statements, one could succeed and the other fail
depending on whether the record actually moved, which is inconsistent.
Now such an update returns an error if it will update a table through multiple aliases, and perform an
update that may physically move the row in at least one of these aliases. (Bug #57373, Bug #11764529,
Bug #55385, Bug #11762751)
• SHOW WARNINGS output following EXPLAIN EXTENDED could include unprintable characters. (Bug
#57341, Bug #11764503)
• Outer joins on a unique key could return incorrect results. (Bug #57034, Bug #11764219)
• For a query that used a subquery that included GROUP BY inside a < ANY() construct, no rows were
returned when there should have been. (Bug #56690, Bug #11763918)
259
MySQL 5.6 Release Notes
• Some RPM installation scripts used a hardcoded value for the data directory, which could result in a
failed installation for users who have a nonstandard data directory location. The same was true for other
configuration values such as the PID file name. (Bug #56581, Bug #11763817)
• On FreeBSD and OpenBSD, the server incorrectly checked the range of the system date, causing legal
values to be rejected. (Bug #55755, Bug #11763089)
• If one connection locked the mysql.func table using either FLUSH TABLES WITH READ LOCK or
LOCK TABLE mysql.func WRITE and a second connection tried to either create or drop a UDF
function, a deadlock occurred when the first connection tried to use a UDF function. (Bug #53322, Bug
#11760878)
• DISTINCT aggregates on DECIMAL UNSIGNED fields could trigger an assertion. (Bug #52171, Bug
#11759827)
• On FreeBSD, if mysqld was killed with a SIGHUP signal, it could corrupt InnoDB .ibd files. (Bug
#51023, Bug #11758773)
• An assertion could be raised if −1 was inserted into an AUTO_INCREMENT column by a statement writing
more than one row. (Bug #50619, Bug #11758417)
• A query that contains an aggregate function but no GROUP BY clause is implicitly grouped. If such a
query also contained an ORDER BY clause, the optimizer could choose to use a temporary table to
perform the ordering. This is unnecessary because implicitly grouped queries return at most one row and
need no ordering. (Bug #47853)
• The parser failed to initialize some internal objects properly, which could cause a server crash in the
cleanup phase after statement execution. (Bug #47511, Bug #11755703)
• When CASE ... WHEN arguments had different character sets, 8-bit values could be referenced as
utf16 or utf32 values, raising an assertion. (Bug #44793, Bug #11753363)
• When using ExtractValue() or UpdateXML(), if the XML to be read contained an incomplete XML
comment, MySQL read beyond the end of the XML string when processing, leading to a crash of the
server. (Bug #44332, Bug #11752979)
• Bitmap functions used in one thread could change bitmaps used by other threads, raising an assertion.
(Bug #43152, Bug #11752069)
• DATE_ADD() and DATE_SUB() return a string if the first argument is a string, but incorrectly returned
a binary string. Now they return a character string with a collation of connection_collation. (Bug
#31384, Bug #11747221)
Changes in MySQL 5.6.1 (Not released, Milestone 5)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
• Performance Schema Notes
260
MySQL 5.6 Release Notes
• Functionality Added or Changed
• Bugs Fixed
Performance Schema Notes
• The Performance Schema has these additions:
• The setup_consumers table contents have changed. Previously, the table used a “flat” structure
with a one-to-one correspondence between consumer name and destination table. This has been
replaced with a hierarchy of consumer settings that enable progressively finer control of which
destinations receive events. The previous xxx_summary_xxx consumers no longer exist. Instead,
the Performance Schema maintains appropriate summaries automatically for the levels for which
settings in the consumer hierarchy are enabled. For example, if only the top-level (global) consumer
is enabled, only global summaries are maintained. Others, such as thread-level summaries, are not.
See Pre-Filtering by Consumer. In addition, optimizations have been added to reduce Performance
Schema overhead.
• It is now possible to filter events by object using the new setup_objects table. Currently, this table
can be used to selectively instrument tables, based on schema names and/or table names. See PreFiltering by Object. A new table, objects_summary_global_by_type, summarizes events for
objects.
• It is now possible to filter events by thread, and the Performance Schema collects more information
for each thread. A new table, setup_actors, can be used to selectively instrument user
connections, based on the user name and/or host name of each connecting session. The
threads table, which contains a row for each active server thread, was extended with several new
columns. With these additions, the information available in threads is like that available from the
INFORMATION_SCHEMA.PROCESSLIST table or the output from SHOW PROCESSLIST. Thus, all three
serve to provide information for thread-monitoring purposes. Use of threads differs from use of the
other two thread information sources in these ways:
• Access to threads does not require a mutex and has minimal impact on server performance.
INFORMATION_SCHEMA.PROCESSLIST and SHOW PROCESSLIST have negative performance
consequences because they require a mutex.
• threads provides additional information for each thread, such as whether it is a foreground or
background thread, and the location within the server associated with the thread.
• threads provides information about background threads. This means that threads can be used to
monitor activity the other thread information sources cannot.
• You can control which threads are monitored by setting the INSTRUMENTED column or by using the
setup_actors table.
For these reasons, DBAs who perform server monitoring using
INFORMATION_SCHEMA.PROCESSLIST or SHOW PROCESSLIST may wish to monitor using threads
instead.
If you upgrade to this MySQL release from an earlier version, you must run mysql_upgrade (and
restart the server) to incorporate these changes into the performance_schema database.
For more information, see MySQL Performance Schema.
Functionality Added or Changed
261
MySQL 5.6 Release Notes
• Incompatible Change: The following obsolete constructs have been removed. Where alternatives are
shown, applications should be updated to use them.
• The --log server option and the log system variable. Instead, use the --general_log option to
enable the general query log and the --general_log_file=file_name option to set the general
query log file name.
• The --log-slow-queries server option and the log_slow_queries system variable.
Instead, use the --slow_query_log option to enable the slow query log and the -slow_query_log_file=file_name option to set the slow query log file name.
• The --one-thread server option. Use --thread_handling=no-threads instead.
• The --skip-thread-priority server option.
• The engine_condition_pushdown system variable. Use the engine_condition_pushdown flag
of the optimizer_switch variable instead.
• The have_csv, have_innodb, have_ndbcluster, and have_partitioning system variables.
Use SHOW ENGINES instead.
• The sql_big_tables system variable. Use big_tables instead.
• The sql_low_priority_updates system variable. Use low_priority_updates instead.
• The sql_max_join_size system variable. Use max_join_size instead.
• The SLAVE START and SLAVE STOP statements. Use the START SLAVE and STOP SLAVE
statements instead.
• The ONE_SHOT modifier for the SET statement.
• Important Change; Replication: Replication filtering options such as --replicate-do-db, -replicate-rewrite-db, and --replicate-do-table were not consistent with one another in
regard to case sensitivity. Now all --replicate-* options follow the same rules for case sensitivity
applying to names of databases and tables elsewhere in the MySQL server, including the effects of the
lower_case_table_names system variable. (Bug #51639, Bug #11759334)
• Important Change; Replication: Added the MASTER_RETRY_COUNT option to the CHANGE MASTER
TO statement, and a corresponding Master_Retry_Count column to the output of SHOW SLAVE
STATUS. The option sets the value shown in this column. MASTER_RETRY_COUNT is intended eventually
to replace the older (and now deprecated) --master-retry-count server option, and is now the
preferred method for setting the maximum number of times that the slave may attempt to reconnect after
losing its connection to the master. (Bug #44209, Bug #11752887, Bug #44486, Bug #11753110)
• InnoDB: Setting innodb_read_ahead_threshold to 0 disables read-ahead. Prior to 5.6.1, a value
of 0 would trigger a read-ahead upon reading the boundary page of a 64 page extent. (Bug #11763876,
Bug #56646)
• InnoDB: InnoDB can now report the total size of the rollback segment, measured in pages. The
value is reported through the information_schema.innodb_metrics table, using the counter
trx_rseg_current_size. You enable and query the counter as follows:
mysql> SET GLOBAL innodb_monitor_enable = 'trx_rseg_current_size';
mysql> SELECT name, count, max_count, comment
->
FROM innodb_metrics WHERE name = 'trx_rseg_current_size';
262
MySQL 5.6 Release Notes
+-----------------------+-------+-----------+----------------------------------------+
| name
| count | max_count | comment
|
+-----------------------+-------+-----------+----------------------------------------+
| trx_rseg_current_size |
346 |
346 | Current rollback segment size in pages |
+-----------------------+-------+-----------+----------------------------------------+
(Bug #57584)
• Replication: SHOW SLAVE STATUS now displays the actual number of retries for each connection
attempt made by the I/O thread. (Bug #56416, Bug #11763675)
• Replication: Added the Slave_last_heartbeat status variable, which shows when a replication
slave last received a heartbeat signal. The value is displayed using TIMESTAMP format. (Bug #45441)
• Replication: Timestamps have been added to the output of SHOW SLAVE STATUS to show when the
most recent I/O and SQL thread errors occurred. The Last_IO_Error column is now prefixed with
the timestamp for the most recent I/O error, and Last_SQL_Error shows the timestamp for the most
recent SQL thread error. The timestamp values use the format YYMMDD HH:MM:SS in both of these
columns. For more information, see SHOW SLAVE STATUS Syntax. (Bug #43535, Bug #11752361,
Bug #64255, Bug #13726435)
• There is now a bind_address system variable containing the value of the --bind-address option.
This enables the address to be accessed at runtime. (Bug #44355, Bug #11752999)
• “Unknown table” error messages that included only the table name now include the database name as
well. (Bug #34750, Bug #11747993)
• Previously, EXPLAIN output for a large union truncated the UNION RESULT row at the end of the list as
follows if the string became too large:
<union1,2,3,4,...>
To make it easier to understand the union boundaries, truncation now occurs in the middle of the string:
<union1,2,3,...,9>
(Bug #30597, Bug #11747073)
• The following items are deprecated and will be removed in a future MySQL release. Where alternatives
are shown, applications should be updated to use them.
• The thread_concurrency system variable.
• The --language server option. Use the lc_messages_dir and lc_messages system variables
instead.
• The --master-retry-count server option. Use the MASTER_RETRY_COUNT option the CHANGE
MASTER TO statement instead.
• Support for adding Unicode collations that are based on the Unicode Collation Algorithm (UCA) has
been improved:
• MySQL now recognizes a larger subset of the LDML syntax that is used to write collation descriptions.
In many cases, it is possible to download a collation definition from the Unicode Common Locale Data
Repository and paste the relevant part (that is, the part between the <rules> and </rules> tags)
into the MySQL Index.xml file.
263
MySQL 5.6 Release Notes
• Character representation in LDML rules is more flexible. Any character can be written literally, not
just basic Latin letters. For collations based on UCA 5.2.0, hexadecimal notation can be used for any
character, not just BMP characters.
• When problems are found while parsing Index.xml, better diagnostics are produced.
• For collations that require tailoring rules, there is no longer a fixed size limit on the tailoring
information.
For more information, see LDML Syntax Supported in MySQL, and Diagnostics During Index.xml
Parsing.
• TO_BASE64() and FROM_BASE64() functions are now available to perform encoding to and from
base-64 strings.
• The Unicode implementation has been extended to include a utf16le character set, which corresponds
to the UTF-16LE encoding of the Unicode character set. This is similar to utf16 (UTF-16) but is littleendian rather than big-endian.
Two utf16le collations are available:
• utf16le_general_ci: The default collation, case sensitive (similar to utf16_general_ci).
• utf16le_bin: Case sensitive, with by-codepoint comparison that provides the same order as
utf16_bin.
There are some limitations on the use of utf16le. With the exception of the item regarding user-defined
collations, these are the same as the limitations on ucs2, utf16, and utf32.
• utf16le cannot be used as a client character set, which means that it also does not work for SET
NAMES or SET CHARACTER SET.
• It is not possible to use LOAD DATA INFILE to load data files that use utf16le.
• FULLTEXT indexes cannot be created on a column that uses utf16le. However, you can perform IN
BOOLEAN MODE searches on the column without an index.
• The use of ENCRYPT() with utf16le is not recommended because the underlying system call
expects a string terminated by a zero byte.
• It is not possible to create user-defined UCA collations for utf16le because there is no
utf16le_unicode_ci collation, which would serve as the basis for such collations.
• Changes to replication in MySQL 5.6 make mysqlbinlog output generated by the --base64output=ALWAYS option unusable. ALWAYS is now an invalid value for this option. If the option is given
without a value, the effect is now the same as --base64-output=AUTO rather than --base64output=ALWAYS.
References: See also: Bug #28760.
• Croatian collations were added for Unicode character sets: utf8_croatian_ci, ucs2_croatian_ci,
utf8mb4_croatian_ci, utf16_croatian_ci, and utf32_croatian_ci. Thee collations have
tailoring for Croatian letters: Č, Ć, Dž, Đ, Lj, Nj, Š, Ž. They are based on Unicode 4.0.
• Several changes were made to optimizer-related system variables:
264
MySQL 5.6 Release Notes
• The optimizer_switch system variable has new engine_condition_pushdown and
index_condition_pushdown flags to control whether storage engine condition pushdown and
index condition pushdown optimizations are used. The engine_condition_pushdown system
variable now is deprecated. For information about condition pushdown, see Engine Condition
Pushdown Optimization, and Index Condition Pushdown Optimization.
• The optimizer_switch system variable has new mrr and mrr_cost_based flags to control use
of the Multi-Range Read optimization. The optimizer_use_mrr system variable has been removed.
For information about Multi-Range Read, see Multi-Range Read Optimization.
• The join_cache_level system variable has been renamed to optimizer_join_cache_level.
This enables a single SHOW VARIABLES LIKE 'optimizer%' statement to show more optimizerrelated settings.
• The Block Nested-Loop (BNL) Join algorithm previously used only for inner joins has been extended and
can be employed for outer join operations, including nested outer joins. For more information, see Block
Nested-Loop and Batched Key Access Joins.
In conjunction with this work, a new system variable, optimizer_join_cache_level, controls how
join buffering is done.
• The OpenGIS specification defines functions that test the relationship between two geometry values.
MySQL originally implemented these functions such that they used object bounding rectangles and
returned the same result as the corresponding MBR-based functions. Corresponding versions are now
available that use precise object shapes. These versions are named with an ST_ prefix. For example,
Contains() uses object bounding rectangles, whereas ST_Contains() uses object shapes. For
more information, see Functions That Test Spatial Relations Between Geometry Objects.
There are also now ST_ aliases for existing spatial functions that were already exact. For example,
ST_IsEmpty() is an alias for IsEmpty()
In addition, the IsSimple() and ST_Distance() spatial functions are now implemented, as well as
the set operator functions ST_Difference(), ST_Intersection(), ST_SymDifference(), and
ST_Union(), (Bug #4249, Bug #11744883)
• A --bind-address option has been added to a number of MySQL client programs: mysql,
mysqldump, mysqladmin, mysqlbinlog, mysqlcheck, mysqlimport, and mysqlshow. This is
for use on a computer having multiple network interfaces, and enables you to choose which interface is
used to connect to the MySQL server.
A corresponding change was made to the mysql_options() C API function, which now has a
MYSQL_OPT_BIND option for specifying the interface. The argument is a host name or IP address
(specified as a string).
Bugs Fixed
• Incompatible Change; Replication: The behavior of INSERT DELAYED statements when using
statement-based replication has changed as follows:
Previously, when using binlog_format=STATEMENT, a warning was issued in the client when
executing INSERT DELAYED; now, no warning is issued in such cases.
Previously, when using binlog_format=STATEMENT, INSERT DELAYED was logged as INSERT
DELAYED; now, it is logged as an INSERT, without the DELAYED option.
265
MySQL 5.6 Release Notes
However, when binlog_format=STATEMENT, INSERT DELAYED continues to be executed as
INSERT (without the DELAYED option). The behavior of INSERT DELAYED remains unchanged when
using binlog_format=ROW: INSERT DELAYED generates no warnings, is executed as INSERT
DELAYED, and is logged using the row-based format.
This change also affects binlog_format=MIXED, because INSERT DELAYED is no longer considered
unsafe. Now, when the logging format is MIXED, no switch to row-based logging occurs. This means that
the statement is logged as a simple INSERT (that is, without the DELAYED option), using the statementbased logging format. (Bug #54579, Bug #11762035)
References: See also: Bug #56678, Bug #11763907, Bug #57666. This issue is a regression of: Bug
#39934, Bug #11749859.
• Incompatible Change; Replication: When determining whether to replicate a CREATE DATABASE,
DROP DATABASE, or ALTER DATABASE statement, database-level options now take precedence over
any --replicate-wild-do-table options. In other words, when trying to replicate one of these
statements, --replicate-wild-do-table options are now checked if and only if there are no
database-level options that apply to the statement. (Bug #46110, Bug #11754498)
• Incompatible Change: Starvation of FLUSH TABLES WITH READ LOCK statements occurred when
there was a constant load of concurrent DML statements in two or more connections. Deadlock occurred
when a connection that had some table open through a HANDLER statement tried to update data through
a DML statement while another connection tried to execute FLUSH TABLES WITH READ LOCK
concurrently.
These problems resulted from the global read lock implementation, which was reimplemented with the
following consequences:
• To solve deadlock in event-handling code that was exposed by this patch, the
LOCK_event_metadata mutex was replaced with metadata locks on events. As a result, DDL
operations on events are now prohibited under LOCK TABLES. This is an incompatible change.
• The global read lock (FLUSH TABLES WITH READ LOCK) no longer blocks DML and DDL on
temporary tables. Before this patch, server behavior was not consistent in this respect: In some cases,
DML/DDL statements on temporary tables were blocked; in others, they were not. Since the main use
cases for FLUSH TABLES WITH READ LOCK are various forms of backups and temporary tables
are not preserved during backups, the server now consistently permits DML/DDL on temporary tables
under the global read lock.
• The set of thread states has changed:
• Waiting for global metadata lock is replaced by Waiting for global read lock.
• Previously, Waiting for release of readlock was used to indicate that DML/DDL
statements were waiting for release of a read lock and Waiting to get readlock was used to
indicate that FLUSH TABLES WITH READ LOCK was waiting to acquire a global read lock. Now
Waiting for global read lock is used for both cases.
• Previously, Waiting for release of readlock was used for all statements that caused an
explicit or implicit commit to indicate that they were waiting for release of a read lock and Waiting
for all running commits to finish was used by FLUSH TABLES WITH READ LOCK.
Now Waiting for commit lock is used for both cases.
• There are two other new states, Waiting for trigger metadata lock and Waiting for
event metadata lock.
266
MySQL 5.6 Release Notes
(Bug #57006, Bug #11764195, Bug #54673, Bug #11762116)
• Incompatible Change: CREATE TABLE statements (including CREATE TABLE ... LIKE) are now
prohibited whenever a LOCK TABLES statement is in effect.
One consequence of this change is that CREATE TABLE ... LIKE makes the same checks as
CREATE TABLE and does not just copy the .frm file. This means that if the current SQL mode is
different from the mode in effect when the original table was created, the table definition might be
considered invalid for the new mode and the statement will fail. (Bug #42546, Bug #11751609)
• InnoDB; Replication: If the master had innodb_file_per_table=OFF,
innodb_file_format=Antelope (and innodb_strict_mode=OFF), or both, certain CREATE
TABLE options, such as KEY_BLOCK_SIZE, were ignored. This could permit the master to avoid raising
ER_TOO_BIG_ROWSIZE errors.
However, the ignored CREATE TABLE options were still written into the binary log, so that, if the slave
had innodb_file_per_table=ON and innodb_file_format=Barracuda, it could encounter an
ER_TOO_BIG_ROWSIZE error while executing the record from the log, causing the slave SQL thread to
abort and replication to fail.
In the case where the master was running MySQL 5.1 and the slave was MySQL 5.5 (or
later), the failure occurred when both master and slave were running with default values for
innodb_file_per_table and innodb_file_format. This could cause problems during upgrades.
To address this issue, the default values for innodb_file_per_table and innodb_file_format
are reverted to the MySQL 5.1 default values—that is, OFF and Antelope, respectively. (Bug #56318,
Bug #11763590)
• InnoDB: If the MySQL Server crashed immediately after creating an InnoDB table, the server could
quit with a signal 11 during the subsequent restart. The issue could occur if the server halted after
InnoDB created the primary index for the table, but before the index definition was recorded in the
MySQL metadata. (Bug #57616)
References: This issue is a regression of: Bug #54582.
• InnoDB: With binary logging enabled, InnoDB could halt during crash recovery with a message referring
to a transaction ID of 0. (Bug #54901, Bug #11762323)
• Replication: Due to changes made in MySQL 5.5.3, settings made in the binlog_cache_size
and max_binlog_cache_size server system variables affected both the binary log statement
cache (also introduced in that version) and the binary log transactional cache (formerly known simply
as the binary log cache). This meant that the resources used as a result of setting either or both
of these variables were double the amount expected. To rectify this problem, these variables now
affect only the transactional cache. The fix for this issue also introduces two new system variables
binlog_stmt_cache_size and max_binlog_stmt_cache_size, which affect only the binary log
statement cache.
In addition, the Binlog_cache_use status variable was incremented whenever either cache was
used, and Binlog_cache_disk_use was incremented whenever the disk space from either cache
was used, which caused problems with performance tuning of the statement and transactional caches,
because it was not possible to determine which of these was being exceeded when attempting to
troubleshoot excessive disk seeks and related problems. This issue is solved by changing the behavior
of these two status variables such that they are incremented only in response to usage of the binary log
transactional cache, as well as by introducing two new status variables Binlog_stmt_cache_use and
267
MySQL 5.6 Release Notes
Binlog_stmt_cache_disk_use, which are incremented only by usage of the binary log statement
cache.
The behavior of the max_binlog_cache_size system variable with regard to active sessions
has also been changed to match that of the binlog_cache_size system variable: Previously, a
change in max_binlog_cache_size took effect in existing sessions; now, as with a change in
binlog_cache_size, a change in max_binlog_cache_size takes effect only in sessions begun
after the value was changed.
For more information, see System Variables Used with Binary Logging, and Server Status Variables.
(Bug #57275, Bug #11764443)
• Replication: The Binlog_cache_use and Binlog_cache_disk_use status variables were
incremented twice by a change to a table using a transactional storage engine. (Bug #56343, Bug
#11763611)
References: This issue is a regression of: Bug #50038.
• Replication: When STOP SLAVE is issued, the slave SQL thread rolls back the current transaction
and stops immediately if the transaction updates only tables which use transactional storage engines.
Previously, this occurred even when the transaction contained CREATE TEMPORARY TABLE statements,
DROP TEMPORARY TABLE statements, or both, although these statements cannot be rolled back.
Because temporary tables persist for the lifetime of a user session (in the case, the replication user),
they remain until the slave is stopped or reset. When the transaction is restarted following a subsequent
START SLAVE statement, the SQL thread aborts with an error that a temporary table to be created (or
dropped) already exists (or does not exist, in the latter case).
Following this fix, if an ongoing transaction contains CREATE TEMPORARY TABLE statements, DROP
TEMPORARY TABLE statements, or both, the SQL thread now waits until the transaction ends, then
stops. (Bug #56118, Bug #11763416)
• Replication: When an error occurred in the generation of the name for a new binary log file, the error
was logged but not shown to the user. (Bug #46166)
References: See also: Bug #37148, Bug #11748696, Bug #40611, Bug #11750196, Bug #43929, Bug
#51019.
• Replication: When lower_case_table_names was set to 1 on the slave, but not on the master,
names of databases in replicated statements were not converted, causing replication to fail on slaves
using case-sensitive file systems. This occurred for both statement-based and row-based replication.
In addition, when using row-based replication with lower_case_table_names set to 1 on the slave
only, names of tables were also not converted, also causing replication failure on slaves using casesensitive file systems. (Bug #37656)
• After setting collation_connection to one of the collations for the ucs2 or utf16 character sets, it
was not possible to change the collation thereafter. (Bug #65000, Bug #13970475)
• cmake -DBUILD_CONFIG=mysql_release on Linux previously required libaio to be linked in. Now
it is possible to specify -DIGNORE_AIO_CHECK to build without libaio. (Bug #58955, Bug #11765940)
• A Valgrind failure occurred in fn_format when called from archive_discover. (Bug #58205, Bug
#11765259)
• Passing a string that was not null-terminated to UpdateXML() or ExtractValue() caused the server
to fail with an assertion. (Bug #57279, Bug #11764447)
268
MySQL 5.6 Release Notes
• In bootstrap mode, the server could not execute statements longer than 10,000 characters. (Bug
#55817, Bug #11763139)
• NULL values were not grouped properly for some joins containing GROUP BY. (Bug #45267, Bug
#11753766)
• A HAVING clause could be lost if an index for ORDER BY was available, incorrectly permitting additional
rows to be returned. (Bug #45227, Bug #11753730)
• The optimizer could underestimate the memory required for column descriptors during join processing
and cause memory corruption or a server crash. (Bug #42744, Bug #11751763)
• The server returned incorrect results for WHERE ... OR ... GROUP BY queries against InnoDB
tables. (Bug #37977, Bug #11749031)
• An incorrectly checked XOR subquery optimization resulted in an assertion failure. (Bug #37899, Bug
#11748998)
• A query that could use one index to produce the desired ordering and another index for range access
with index condition pushdown could cause a server crash. (Bug #37851, Bug #11748981)
• With index condition pushdown enabled, InnoDB could crash due to a mismatch between what
pushdown code expected to be in a record versus what was actually there. (Bug #36981, Bug
#11748647)
• The range optimizer ignored conditions on inner tables in semi-join IN subqueries, causing the optimizer
to miss good query execution plans. (Bug #35674, Bug #11748263)
• A server crash or memory overrun could occur with a dependent subquery and joins. (Bug #34799, Bug
#11748009)
• Selecting from a view that referenced the same table in the FROM clause and an IN clause caused a
server crash. (Bug #33245)
• Deeply nested subqueries could cause stack overflow or a server crash. (Bug #32680, Bug #11747503)
• The server crashed on optimization of queries that compared an indexed DECIMAL column with a string
value. (Bug #32262, Bug #11747426)
• The server crashed on optimizations that used the range checked for each record access
method. (Bug #32229, Bug #11747417)
• Contains() failed for multipolygon geometries. (Bug #32032, Bug #11747370)
• If the optimizer used a Multi-Range Read access method for index lookups, incorrect results could occur
for rows that contained any BLOB or TEXT data types. (Bug #30622, Bug #11747076)
• Compared to MySQL 5.1, the optimizer failed to use join buffering for certain queries, resulting in slower
performance for those queries. (Bug #30363, Bug #11747028)
• For Multi-Range Read scans used to resolve LIMIT queries, failure to close the scan caused file
descriptor leaks for MyISAM tables. (Bug #30221, Bug #11746994)
• SHOW CREATE DATABASE did not account for the value of the lower_case_table_names system
variable. (Bug #21317, Bug #11745926)
269
MySQL 5.6 Release Notes
Changes in MySQL 5.6.0 (Not released, Milestone 4)
Note
This is a milestone release, for use at your own risk. Upgrades between milestone
releases (or from a milestone release to a GA release) are not supported.
Significant development changes take place in milestone releases and you may
encounter compatibility issues, such as data format changes that require attention
in addition to the usual procedure of running mysql_upgrade. For example, you
may find it necessary to dump your data with mysqldump before the upgrade and
reload it afterward.
• Performance Schema Notes
• Globally Unique Server IDs
• Functionality Added or Changed
• Bugs Fixed
Performance Schema Notes
• The Performance Schema now includes instrumentation for table input and output. Instrumented
operations include row-level accesses to persistent base tables or temporary tables. Operations that
affect rows are fetch, insert, update, and delete. For a view, waits are associated with base tables
referenced by the view.
Globally Unique Server IDs
• Replication: Globally unique IDs for MySQL servers were implemented. A UUID is now obtained
automatically when the MySQL server starts. The server first checks for a UUID written in the auto.cnf
file (in the server's data directory), and uses this UUID if found. Otherwise, the server generates a new
UUID and saves it to this file (and creates the file if it does not already exist). This UUID is available as
the server_uuid system variable.
MySQL replication masters and slaves know each other's UUIDs. The value of a slave's UUID can be
read in the output of SHOW SLAVE HOSTS. After a slave is started using START SLAVE, the value of
the master's UUID is available on the slave in the output of SHOW SLAVE STATUS. (Bug #33815, Bug
#11747723)
References: See also: Bug #16927, Bug #11745543.
Functionality Added or Changed
• Partitioning: It is now possible to exchange a partition of a partitioned table or a subpartition of a
subpartitioned table with a nonpartitioned table that otherwise has the same structure using the ALTER
TABLE ... EXCHANGE PARTITION statement. This can be used, for example, for importing and
exporting partitions.
For more information and examples, see Exchanging Partitions and Subpartitions with Tables.
• Replication: These unused and deprecated items have been removed: the --init-rpl-role and
--rpl-recovery-rank options, the rpl_recovery_rank system variable, and the Rpl_status
status variable. (Bug #54649, Bug #11762095)
References: See also: Bug #34437, Bug #11747900, Bug #34635, Bug #11747961.
270
MySQL 5.6 Release Notes
• Replication: The SHOW SLAVE STATUS statement now has a Master_Info_File field indicating the
location of the master.info file. (Bug #50316, Bug #11758151)
• Replication: MySQL now supports delayed replication such that a slave server deliberately lags
behind the master by at least a specified amount of time. The default delay is 0 seconds. Use the new
MASTER_DELAY option for CHANGE MASTER TO to set the delay to N seconds:
CHANGE MASTER TO MASTER_DELAY = N;
An event received from the master is not executed until at least N seconds later than its execution on the
master.
START SLAVE and STOP SLAVE take effect immediately and ignore any delay. RESET SLAVE resets
the delay to 0.
SHOW SLAVE STATUS has three new fields that provide information about the delay:
• SQL_Delay: The number of seconds that the slave must lag the master.
• SQL_Remaining_Delay: When Slave_SQL_Running_State is Waiting until
MASTER_DELAY seconds after master executed event, this field contains the number of
seconds left of the delay. At other times, this field is NULL.
• Slave_SQL_Running_State: The state of the SQL thread (analogous to Slave_IO_State). The
value is identical to the State value of the SQL thread as displayed by SHOW PROCESSLIST.
When the slave SQL thread is waiting for the delay to elapse before executing an event, SHOW
PROCESSLIST displays its State value as Waiting until MASTER_DELAY seconds after
master executed event.
The relay-log.info file now contains the delay value, so the file format has changed. See Slave
Status Logs. In particular, the first line of the file now indicates how many lines are in the file. If you
downgrade a slave server to a version older than MySQL 5.6, the older server will not read the file
correctly. To address this, modify the file in a text editor to delete the initial line containing the number of
lines.
The introduction of delayed replication entails these restrictions:
• Previously the BINLOG statement could execute all types of events. Now it can execute only format
description events and row events.
• The output from mysqlbinlog --base64-output=ALWAYS cannot be parsed. ALWAYS becomes
an invalid value for this option in 5.6.1.
For additional information, see Delayed Replication. (Bug #28760, Bug #11746794)
• The Romansh locale 'rm_CH' is now a permissible value for the lc_time_names system variable.
(Bug #50915, Bug #11758678)
• mysqlbinlog now has a --binlog-row-event-max-size option to enable large row events to be
read from binary log files. (Bug #49932)
• mysqldump now has an --add-drop-trigger option which adds a DROP TRIGGER IF EXISTS
statement before each dumped trigger definition. (Bug #34325, Bug #11747863)
• Vietnamese collations were added for the Unicode character sets. Those based on Unicode
Collation Algorithm 5.2.0 have names of the form xxx_vietnamese_520_ci (for example,
271
MySQL 5.6 Release Notes
utf8_vietnamese_520_ci). Those based on Unicode Collation Algorithm 4.0.0 have names of the
form xxx_vietnamese_ci (for example, utf8_vietnamese_ci). These collations are the same as
the corresponding xxx_unicode_520_ci and xxx_unicode_ci collations except for precomposed
characters which are accented versions of “A”, “D”, “E”, “O”, and “U”. There is no change to ideographic
characters derived from Chinese. There are no digraphs.
• Unicode collation names now may include a version number to indicate the Unicode Collation Algorithm
(UCA) version on which the collation is based. Initial collations thus created use version UCA 5.2.0. For
example, utf8_unicode_520_ci is based on UCA 5.2.0. UCA-based Unicode collation names that do
not include a version number are based on version 4.0.0.
LOWER() and UPPER() perform case folding according to the collation of their argument. A character
that has uppercase and lowercase versions only in a Unicode version more recent than 4.0.0 will be
converted by these functions only if the argument has a collation that uses a recent enough UCA
version.
The LDML rules for creating user-defined collations are extended to permit an optional version
attribute in <collation> tags to indicate the UCA version on which the collation is based. If the
version attribute is omitted, its default value is 4.0.0. See Adding a UCA Collation to a Unicode
Character Set.
• In MySQL 5.5, setting optimizer_search_depth to the deprecated value of 63 switched to the
algorithm used in MySQL 5.0.0 (and previous versions) for performing searches. The value of 63 is now
treated as invalid.
• The Unicode character sets now have a xxx_german2_ci collation that provides DIN-2 (phone book)
ordering (for example, utf8_german2_ci). See Unicode Character Sets.
• mysqlbinlog now has the capability to back up a binary log in its original binary format. When invoked
with the --read-from-remote-server and --raw options, mysqlbinlog connects to a server,
requests the log files, and writes output files in the same format as the originals. See Using mysqlbinlog
to Back Up Binary Log Files.
• A new SQL function, WEIGHT_STRING(), returns the weight string for an input string. The weight string
represents the sorting and comparison value of the input string. See String Functions.
Bugs Fixed
• Security Fix: A security bug was fixed. (Bug #49124)
• InnoDB: The server could crash on shutdown, if started with --innodb-use-system-malloc=0.
(Bug #55581, Bug #11762927)
• Replication: The internal flag indicating whether a user value was signed or unsigned
(unsigned_flag) could sometimes change between the time that the user value was recorded for
logging purposes and the time that the value was actually written to the binary log, which could lead to
inconsistency. Now unsigned_flag is copied when the user variable value is copied, and the copy of
unsigned_flag is then used for logging. (Bug #51426, Bug #11759138)
References: See also: Bug #49562, Bug #11757508.
• Microsoft Windows: On Windows, an IPv6 connection to the server could not be made using an IPv4
address or host name. (Bug #52381, Bug #11760016)
• Microsoft Windows: On Windows, the my_rename() function failed to check whether the source file
existed. (Bug #51861, Bug #11759540)
272
MySQL 5.6 Release Notes
• Microsoft Windows: On Windows, mysqlslap crashed for attempts to connect using shared memory.
(Bug #31173, Bug #11747181, Bug #59107, Bug #11766072)
• The embedded server could crash when determining which directories to search for option files. (Bug
#55062, Bug #11762465)
• Performance Schema code was subject to a buffer overflow. (Bug #53363)
• Subquery execution for EXPLAIN could be done incorrectly and raise an assertion. (Bug #52317, Bug
#11759957)
• There was a mixup between GROUP BY and ORDER BY concerning which indexes should be considered
or permitted during query optimization. (Bug #52081, Bug #11759746)
• The ref column of EXPLAIN output for subquery lines could be missing information. (Bug #50257, Bug
#11758106)
• Passwords for CREATE USER statements were written to the binary log in cleartext rather than in
ciphertext. (Bug #50172)
• The BLACKHOLE storage engine failed to load on Solaris and OpenSolaris if DTrace probes had been
enabled. (Bug #47748, Bug #11755909)
• Some error messages included a literal mysql database name rather than a parameter for the database
name. (Bug #46792, Bug #11755079)
• In the ER_TABLEACCESS_DENIED_ERROR error message, the command name parameter could be
truncated. (Bug #45355, Bug #11753840)
• To forestall the occurrence of possible relocation errors in the future, libmysys, libmystrings, and
libdbug have been changed from normal libraries to “noinst” libtool helper libraries, and are no
longer installed as separate libraries. (Bug #29791, Bug #11746931)
• A suboptimal query execution plan could be chosen when there were several possible range and ref
accesses. Now preference is given to the keys that match the most parts and choosing the best one
among them. (Bug #26106, Bug #11746406)
• Searches for data on a partial index for a column using the utf8 character set failed. (Bug #24858)
• For queries with GROUP BY, FORCE INDEX was not ignored as it should have been when it would result
in a more expensive query execution plan. (Bug #18144, Bug #11745649)
Index
Symbols
!=, 159
--add-drop-trigger, 270
--all-databases, 213
--base64-output, 104, 226
--binary-as-hex, 4
--binary-mode, 226
--bind-address, 159, 174, 260
--binlog-checksum, 248
--binlog-ignore-db, 104
--binlog-row-event-max-size, 270
--binlog-rows-query-log-events, 248
273
MySQL 5.6 Release Notes
--bootstrap, 149, 174
--connect-expired-password, 104
--database, 104, 197
--default-auth, 248
--defaults-extra-file, 226
--defaults-file, 248
--disable-gtid-unsafe-statements, 159
--dump-slave, 104
--enable-cleartext-plugin, 27
--exclude-gtids, 104
--flush-logs, 197
--gtid-mode, 197
--gtid_mode, 65
--help, 69
--hexdump, 213
--histignore, 149
--ignore-db-dir, 226
--include-gtids, 104
--include-master-host-port, 104
--init-rpl-role, 270
--log-bin, 130, 197
--log-slave-updates, 104
--log-warnings, 69
--master-data, 213
--master-info-repository, 130, 159
--master-verify-checksum, 248
--open-files-limit, 94
--plugin-dir, 149, 248
--plugin-load, 226
--plugin-load-add, 226
--print-defaults, 37
--raw, 58, 226
--read-from-remote-server, 104
--relay-log, 197
--relay-log-info-file, 88
--relay-log-info-repository, 130
--relay-log-recovery, 174
--relay-log-space-limit, 174
--replicate-do-db, 65
--replicate-ignore-db, 65
--replicate-ignore-table, 159
--replicate-rewrite-db, 159
--replicate-wild-ignore-table, 104
--report-port, 197
--routines, 197
--rpl-recover-rank, 270
--secure-auth, 69, 114
--server-id, 197, 226
--single-transaction, 197
--skip-gtids, 104
--skip-innodb, 54, 130
--skip-slave-start, 197
--slave-max-allowed-packet, 174
--slave-parallel-workers, 69, 88
274
MySQL 5.6 Release Notes
--slave-rows-search-algorithms, 174
--slave-skip-errors, 149
--slave-skip-errors=all, 69
--slave-sql-verify-checksum, 248
--slave_parallel_workers, 213
--slow-start-timeout, 197
--ssl, 21
--ssl-crl, 226
--ssl-crlpath, 226
--ssl-key, 159, 226
--ssl-mode, 6, 21
--ssl-verify-server-cert, 21
--start-position, 197, 226
--stop-never, 104
--verbose, 81, 104, 248
--write-binlog, 159
--xml, 197
.frm, 94
.par, 94
64-bit, 159
,4
A
adaptive_hash_searches_btree, 46
ADD, 42
ADD FOREIGN KEY, 54
ADD FULLTEXT, 81
ADD INDEX, 24, 46
ADD PARTITION, 197
ADD PRIMARY KEY, 88, 114
AES_DECRYPT(), 69, 88, 104, 130
AES_ENCRYPT(), 69, 88, 130
AGAINST, 75
aggregate functions, 149, 197
ALGORITHM, 49, 94, 114
ALL_SIGNED, 94
ALL_UNSIGNED, 94
ALTER DATABASE, 248, 260
ALTER EVENT, 226
ALTER SERVER, 159
ALTER TABLE, 11, 15, 24, 27, 29, 34, 37, 42, 46, 49, 54, 58, 69, 75,
81, 81, 88, 94, 104, 114, 130, 140, 159, 174, 197, 213, 226, 248, 270
ALTER TABLE INPLACE, 104
ALTER USER, 149, 159, 174
ANALYZE TABLE, 24
append, 42
Append_block events, 226
ARCHIVE, 68, 114, 174, 197, 213
ARM64, 29
assertion, 75, 88, 94, 104, 114, 149
assertion failure, 88
asterisk, 94
attribute promotion, 94, 226
275
MySQL 5.6 Release Notes
audit_log plugin, 21, 29, 42, 46, 54, 58, 69, 94, 104
authentication, 69, 81, 114, 140, 149, 213, 248
authentication plugins, 248
auto-increment, 69
auto.cnf, 65, 270
autocommit, 27, 88, 114, 248
AUTOMATIC, 58, 104
AUTO_INCREMENT, 29, 58, 114, 130, 174, 226, 248
AUTO_POSITION, 114
Auto_Position, 130
avoid_temporal_upgrade, 42
B
B-tree, 49
backport, 69
backticks, 114, 149
backup, 37, 69
barracuda, 88
BEGIN, 174
BETWEEN, 197
BIGINT, 197
binary log, 15, 16, 21, 27, 29, 46, 49, 54, 75, 81, 88, 104, 114, 130, 159,
226, 248
binary log events, 69, 114
binary log rotation, 94
bind-address, 260
bind_address, 260
binlog, 49, 58, 65, 81, 104, 114, 130, 140
BINLOG, 270
binlog events, 130
binlog rotation, 104
Binlog_cache_disk_use, 260
binlog_cache_size, 260
Binlog_cache_use, 260
binlog_cache_use, 260
binlog_checksum, 174, 248
BINLOG_DUMP_NON_BLOCK, 58
binlog_error_action, 24, 29
binlog_format, 104, 149, 260
binlog_rows_query_log_events, 174
binlog_row_image, 37, 81, 248
Binlog_stmt_cache_disk_use, 260
binlog_stmt_cache_size, 260
Binlog_stmt_cache_use, 260
BIN_LOG_HEADER_SIZE , 197
BLACKHOLE, 104
blackhole, 270
BLOB, 49, 58, 69, 88, 104, 226
block nested loop, 260
block_encryption_mode, 69
boolean mode, 21, 81, 94
btr0cur.cc, 75
btr_root_raise_and_insert, 46
276
MySQL 5.6 Release Notes
btr_validate_level, 81
buf0flu.cc, 88
buffer manager, 104
buffer pool, 24, 65, 69, 88, 94, 114
buf_page_get_gen, 88
buf_validate, 104
build error, 69
C
C API, 4, 6, 15, 16, 21, 24, 27, 37, 65, 81, 88, 94, 104, 114, 130, 197
cache_policies, 75
Can't find record, 226
change buffer, 34, 46, 81
CHANGE COLUMN, 49
CHANGE MASTER TO, 81, 88, 94, 114, 130, 159, 174, 197, 213, 248, 260, 270
CHAR, 197
character sets, 11, 16, 24, 29, 42, 49, 54, 65, 69, 75, 114, 140, 159, 174,
226, 248, 270
CHARSET, 114
charset2html, 65
CHECK TABLE, 81, 94, 140, 159, 226
checksum, 27, 49
CHECKSUM TABLE, 213
checksums, 248
cleartext_plugin, 159
client, 197
client API, 58
clients, 37
CLIENT_REMEMBER_OPTIONS, 54
close_temporary_tables(), 58
clustered index, 114
CMake, 27, 69, 94, 104, 149, 159, 174, 226
cmp_dtuple_rec_with_match, 69
collations, 159, 174, 197, 260, 270
column length, 42
comment, 94
comments, 174, 248
COMMIT, 149, 174
commit_threads_m, 94
comparison operators, 197
compilation, 248
compiling, 4, 6, 11, 15, 18, 24, 27, 29, 34, 37, 42, 46, 49, 58, 65,
69, 75, 81, 88, 94, 159, 174, 270
compressed slave, 54
compressed table, 54, 69
compression, 34
COM_BINLOG_DUMP, 197
COM_CHANGE_USER, 94
COM_STATISTICS, 197
Com_xxx, 174
CONCAT(), 174, 226
concurrent transactions, 197
condition pushdown, 248
277
MySQL 5.6 Release Notes
configuration, 6, 24, 42, 49, 58, 69, 75, 81, 104, 114, 149, 159, 174, 197, 213,
226, 248, 260
connection-server-id, 58
connections, 226
CONNECTION_CONTROL plugin, 6, 11
CONNECTION_CONTROL_FAILED_LOGIN_ATTEMPTS plugin, 11
CONNECTION_ID(), 140
consistency, 65
constraint violation, 29
constraints, 46, 94
containers table, 81
Contains(), 260
CONV(), 81
conversion, 81
CONVERT_TZ(), 114
corruption, 75, 104
COUNT(), 4
counter, 81
CPU, 58
crash recovery, 49, 69, 104, 114
CRC32, 114
CREATE ... SELECT, 248
CREATE DATABASE, 260
CREATE EVENT, 226
CREATE FUNCTION, 174
CREATE INDEX, 27, 174
CREATE SERVER, 159
CREATE TABLE, 6, 21, 29, 37, 49, 69, 81, 94, 114, 174, 226, 260
CREATE TABLE ... SELECT, 65, 197
CREATE TABLE LIKE, 88
CREATE TEMPORARY TABLE, 65, 226
CREATE USER, 18, 149, 226, 270
CREATE VIEW, 197
Create_file events, 226
CREATE_TIME, 37
current_thd, 46
D
data corruption, 54, 81
data dictionary, 46, 49
DATA DIRECTORY, 21, 37
data file, 27, 69
data file path, 24
data file size, 69
data integrity, 159
data types, 69, 114, 213
database, 130
database name, 49, 81
DATE(), 197, 226
DATETIME, 197, 248
DB_PRODUCTION, 69
DDL, 18, 24, 75, 197
deadlock, 18, 42, 104
278
MySQL 5.6 Release Notes
deadlocks, 226
Debian, 49
debug, 49, 54, 75, 104
debug assertion, 75
debug build, 69, 149
Debug Sync, 6, 65, 197
DECIMAL, 75, 88, 213
decr, 42, 46
default database, 104
default storage engine, 81
DEFAULT_AUTH, 213
default_tmp_storage_engine, 226
DELETE, 46
Delete_rows_log_event, 104
deprecation, 49, 149
DES_DECRYPT(), 248
DES_ENCRYPT(), 248
dictionary, 34
DICT_CHECK_TABLESPACES_AND_STORE_MAX_ID, 104
DICT_FK_MAX_RECURSIVE_LOAD, 104
dict_set_corrupted, 49
dict_update_statistics, 104
DISCARD TABLESPACE, 75, 81
disk full, 27, 114, 149
DISTINCT, 149
DIV, 248
DML, 24, 42, 46, 130, 197, 248
doublewrite buffer, 69, 75
downgrades, 21
DROP DATABASE, 34, 88, 104, 174, 197, 226, 248, 260
DROP INDEX, 18, 27, 88, 104
DROP SERVER, 159
DROP TABLE, 58, 81, 94, 114, 130, 197
DROP TEMPORARY TABLE, 65, 88
DROP TRIGGER, 69
DROP USER, 149
DTrace, 54, 58
dump thread, 29, 69, 81, 88
duplicate key, 104
duplicate key error, 27
duplicate key value, 54
E
EE_FILENOTFOUND, 226
EIO, 58
el5, 6
el6, 4
empty transactions, 65
encryption, 4, 6, 11, 14, 18, 21, 24, 27, 29, 46, 49, 54, 69
enforce-gtid-consistency, 140
engine_condition_pushdown, 260
ENOSPC, 58
enter value, 18, 29
279
MySQL 5.6 Release Notes
ENUM, 114
EOF, 114
Error 1034, 81
Error 1160, 197
Error 1168, 197
Error 1201, 174
error 2006, 197
error 2013, 197
error code, 75
error handling, 58, 104
error log, 69, 81, 149, 159, 226
error logging, 149
error message, 46, 54, 69, 88, 114, 149, 174, 226
errors, 11, 15, 18, 21, 24, 29, 42, 46, 69, 81, 88, 94, 104, 114, 130, 140,
149, 159, 174, 197, 213, 226, 248, 260, 270
ERROR_FOR_DIVISION_BY_ZERO, 69
error_key_num, 81
Error_log_throttle, 69
ERR_LOCK_WAIT_TIMEOUT, 29
ER_AUTO_POSITION_REQUIRES_GTID_MODE_ON, 174
ER_BINLOG_UNSAFE_STATEMENT, 159
ER_GTID_NEXT_TYPE_UNDEFINED_GROUP, 29, 54
ER_SLAVE_IGNORE_TABLE, 69
ER_SLAVE_INCIDENT, 226
ER_UNKNOWN_SYSTEM_VARIABLE, 114
event checksums, 29
event offsets, 75
event scheduler, 88, 104, 149
events, 46, 197
exact search, 81
EXCHANGE PARTITION, 174, 226, 270
Executed_Gtid_Set, 29, 130
exec_time, 75
expiration time, 42
EXPLAIN, 65, 114, 130, 140, 149, 159, 197, 260, 270
EXPLAIN EXTENDED, 226, 248
explain_filename, 104
explicit_defaults_for_timestamp, 159, 174
export, 46
exptime, 37, 42
EXTRACT(), 248
ExtractValue(), 21, 75, 159, 260
F
failover, 130
FEDERATED, 15, 21, 42, 46, 75, 104, 159, 197, 213
Fedora, 18
file format, 29, 88
file size, 75
files, 197
FILE_PAGE_WAS_FREED, 130
filtering options, 260
fil_node_open_file, 88
280
MySQL 5.6 Release Notes
FIND_IN_SET(), 248
firewall, 27, 34, 37, 42
FLOAT, 197
FLUSH LOGS, 149, 174
flush method, 34
FLUSH TABLES, 18, 46, 65, 69, 104
FLUSH TABLES WITH READ LOCK, 94
flushing, 58, 65
flush_all, 29, 42
FOR EXPORT, 46, 69
force recovery, 81
FOREIGN KEY, 94
foreign key constraint, 88, 104
foreign keys, 18, 34, 37, 46, 54, 58, 69, 94, 114, 159
foreign_key_checks, 94, 104
format descriptors, 114
FORMAT(), 114
formatting, 4
FOUND_ROWS(), 94, 104, 114
FreeBSD, 226, 248
FROM_BASE64(), 260
fsync(), 104
fts0vlc.ic, 42
fts_add_doc_by_id, 49
FTS_CHILD_EXITING, 114
fts_optimize_thread, 49
fts_tokenizer_word_get, 49
full-text, 16, 46, 49, 58, 75, 81, 88, 94, 104, 130
full-text index, 16, 18, 21, 24, 34, 81
full-text search, 11, 15, 16, 18, 21, 24, 34, 37, 42, 46, 49, 58, 65, 69,
75, 81, 94, 104, 114, 130, 174
FULLTEXT index, 18, 42, 140, 213
function, 49
functions, 81
G
GCC, 29
gcov, 174
general_log, 174
get, 54
get_string_length(), 81
GIS, 16, 37, 54, 81, 94, 104, 130, 149, 159, 260
glibc, 11
global locks, 94
GRANT, 81, 149, 159
group commit, 104
GROUP_CONCAT(), 104, 174, 213
group_concat_max_len, 42, 174
group_relay_log_pos, 65
GTID, 4, 24, 34, 37, 42, 46, 49, 54, 104, 174
gtid-mode, 140
GTIDs, 29, 54, 58, 81, 94, 104, 114, 130, 140, 159, 174, 197
gtid_executed, 114
281
MySQL 5.6 Release Notes
GTID_log_event, 104
gtid_mode, 42, 65, 130, 149
gtid_next, 54, 58, 94, 104, 114
GTID_NEXT_LIST, 94
gtid_purged, 114, 140
GTID_SUBSET(), 114
GTID_SUBTRACT(), 114, 140
H
HANDLER, 174
hang, 58, 69, 81, 149
HASH, 75, 159, 197
hash_lock arrayk, 114
HASH_SCAN, 54
have_profiling, 149
HAVING, 197
HA_ERR_KEY_NOT_FOUND, 75
ha_innobase, 88
header, 58
heap block, 75
heartbeat, 260
heartbeats, 114
HEARTBEAT_LOG_EVENT, 114
Heartbleed, 68
hostname, 149
host_cache, 197
host_cache_size, 197
I
I/O cache, 75
ibd file, 27
ibdata, 27
identifiers, 114, 149
IF EXISTS, 88
IF(), 104
ignore_db_dirs, 226
implicit commit, 104, 114, 130, 159, 197
IMPORT TABLESPACE, 27, 34, 114
Important Change, 58, 69, 88, 94, 104, 114, 130, 140, 149, 159, 174, 197, 213, 226,
248, 260
Important Note, 114
impossible WHERE, 149
Incompatible Change, 11, 14, 16, 69, 81, 88, 94, 104, 114, 140, 159, 174, 197,
213, 226, 248, 260
incr, 46
index, 81, 94, 197
INDEX DIRECTORY, 37
index files, 197
index key, 149
index merge, 226
index page, 94
index record, 29
index scan, 94
282
MySQL 5.6 Release Notes
index tables, 58
index_merge, 75
index_merge_intersection, 69
index_next, 81
index_read_map, 81
INET6_ATON(), 114, 226
INET6_NTOA(), 114, 226
infinite loop, 88
info repository, 130
INFORMATION_SCHEMA, 37, 42, 46, 65, 130, 197
information_schema, 81, 248
INFORMATION_SCHEMA.INNODB_METRICS, 94
INFORMATION_SCHEMA.PARTITIONS, 37, 88, 174
INFORMATION_SCHEMA.TABLES, 37, 65
initialize, 75
init_command, 197
init_file, 248
innobase_get_col_names, 75
innobase_rollback, 94
innochecksum, 75
InnoDB, 4, 6, 11, 15, 16, 18, 21, 24, 27, 29, 34, 37, 42, 46, 49,
54, 58, 65, 69, 75, 81, 88, 94, 104, 114, 130, 140, 149, 159, 174, 197, 213,
226, 248, 260, 270
InnoDB Lock Monitor, 49
InnoDB Monitor, 49
innodb_additional_mem_pool_size, 226
innodb_allocate, 75
innodb_api_enable_binlog, 75
innodb_api_enable_mdl, 114
innodb_buffer_pool_size, 81
INNODB_BUFFER_POOL_SIZE, 104
innodb_checksum_algorithm, 37, 49
innodb_data_file_path, 58
innodb_fast_shutdown, 94
innodb_file_format, 260
innodb_file_per_table, 130, 260
innodb_force_recovery, 29, 49, 81
innodb_ft_default_stopword, 114
INNODB_FT_INDEX_TABLE, 81
innodb_index_stats, 69
innodb_limit_optimistic_insert_debug, 49
innodb_locks_unsafe_for_binlog, 226
innodb_log_buffer_size, 104
innodb_log_file_size, 46
innodb_log_group_home_dir, 88
innodb_max_purge_lag, 197
INNODB_MEMCACHE.CONTAINERS, 159
INNODB_METRICS, 46
innodb_metrics, 81
innodb_mirrored_log_groups, 114
innodb_monitor_enable, 16
innodb_numa_interleave, 29
innodb_read_only, 94
innodb_rwlock_x_spin_waits, 94
283
MySQL 5.6 Release Notes
innodb_stats_on_metadata, 88
innodb_stats_sample_pages, 226
innodb_strict_mode, 49
innodb_sync_array_size, 114
innodb_table_monitor, 226
innodb_tmpdir, 24
innodb_use_sys_malloc, 226
INPLACE, 49, 75, 114
INSERT, 18, 46, 54, 69, 88, 94, 104, 174
INSERT ... SELECT, 197
insert buffer, 29
insert buffer merge, 94
INSERT DELAYED, 159, 174, 260
INSERT IGNORE, 248
INSERT ON DUPLICATE KEY UPDATE, 174, 226, 248
insert operations, 149
INSERT_ID, 130, 197
INSTALL PLUGIN, 16
installing, 4, 6, 11, 16, 18, 27, 34, 46, 49, 54, 58, 69, 75, 81, 94,
104, 114, 174, 213, 226, 248
INT, 197
invalid page type, 94
invalid pointer, 94
inverse document frequency, 58
IPv6, 159, 174, 226
IS NULL, 248
isl file, 75
isolation level, 88
IS_FREE_LOCK(), 49
IS_IPV4(), 226
IS_IPV4_COMPAT(), 226
IS_IPV4_MAPPED(), 226
IS_IPV6(), 226
IS_USED_LOCK(), 49
Item::print, 226
I_S.INNODB_TEMP_TABLE_INFO, 65
J
joins, 104, 260
K
KEY, 49, 159, 197
KILL, 81, 140
L
Last_Error, 94
LAST_INSERT_ID, 81
LAST_INSERT_ID(), 140, 174
Last_IO_Error, 226
Last_SQL_Error, 94, 226
LDML, 260
lettercase, 260
libedit, 114, 213, 226
284
MySQL 5.6 Release Notes
libevent, 75
libmysqlclient, 149
libmysqld, 24, 114, 174, 197, 226, 270
LIBMYSQL_PLUGIN_DIR, 130
libraries, 270
licensing, 248
LIKE, 140, 174, 248
LIMIT, 159
limitations, 69
linefeeds, 197
LinuxThreads, 58
LIST, 197
LIST COLUMNS, 58
LOAD DATA, 94
LOAD DATA ... SET, 81
LOAD DATA INFILE, 58, 140, 226, 248
LOAD INDEX INTO CACHE, 197
LOAD XML, 29
LOAD XML INFILE, 4
locale, 270
lock monitor, 75
LOCK TABLES, 197, 260
locking, 29, 34, 46, 49, 54, 58, 69, 75, 81, 88, 94, 104, 114, 130, 140,
149, 159, 174, 197, 213, 226, 248, 260
LOCK_ORDINARY, 104
LOCK_REC_NOT_GAP, 104
lock_rec_restore_from_page_infimum, 94
lock_validate, 114
log buffer, 81
log error, 54
log file corruption, 104
log files, 104
log rotation, 29, 88, 104, 114
log tables, 140, 213
log-bin, 159, 248
log-slave-updates, 88
logging, 11, 15, 21, 37, 42, 46, 54, 69, 81, 88, 104, 130, 140, 149, 174,
197, 213, 226, 248
loggins, 226
log_bin_basename, 248
log_event.h, 94
log_slow_admin_statements, 114
log_slow_slave_statements, 114
log_throttle_queries_not_using_indexes, 197
log_warnings, 75
lost connection, 21
LOST_EVENTS, 81
lowercase, 49
lower_case_table_names, 29, 213, 226, 260
LOW_PRIORITY, 197
LPAD(), 54
LRU flushing, 104
LSN, 49, 88, 104
285
MySQL 5.6 Release Notes
M
MAKETIME(), 174
make_win_bin_dist, 213
mapping_db_to_worker, 159
Masrter_id, 159
master info repository, 94
master thread, 54
master-bind, 248
master-info-repository, 88
master-slave protocol, 140
master.info, 226
MASTER_AUTO_POSITION, 81, 130, 140, 174, 197
MASTER_DELAY, 88, 174
master_info_repository, 54, 69, 248
MASTER_LOG_FILE, 248
MASTER_PASSWORD, 94, 213
MASTER_POS_WAIT(), 130
MASTER_RETRY_COUNT, 260
MASTER_SSL_CRL, 69
MASTER_SSL_CRLPATH, 69
MASTER_USER, 94, 213
MATCH, 75
MAX(), 174, 197, 226
max_allowed_packet, 174, 226, 248
max_binlog_cache_size, 69, 159, 260
max_binlog_stmt_cache_size, 159, 260
max_connections, 114, 197
max_connect_errors, 149
max_digest_length, 34
max_long_data_size, 226
MAX_USER_CONNECTIONS, 174
MD5(), 174
MDEV-6615, 29
memcached, 4, 6, 18, 29, 34, 37, 42, 46, 54, 58, 69, 75, 81, 88, 94,
104
memcached plugin, 159
memcpy, 69
memmove, 69
memory, 4, 54, 58, 69, 75, 81
MEMORY, 140, 197, 213
memory access error, 69
memory access violation, 49, 54, 69, 75
memory allocation, 29
memory consumption, 94
memory leak, 81, 94, 104
memory usage, 54, 75
memset, 65
MEM_HEAP_CREATE_BLOCK, 104
merge, 94
MERGE, 197, 226
merge insert buffer, 75
metadata, 46, 174
286
MySQL 5.6 Release Notes
Microsoft Windows, 6, 18, 24, 29, 49, 69, 75, 114, 130, 140, 159, 174, 197, 226,
248, 270
MIN(), 174, 197, 226, 248
MINIMAL, 81
MOD, 54
MODIFY, 27
monitor, 69, 75
MRR, 197
MRR_SORTED, 197
msql2mysql, 69
mtr_memo_contains, 81
mtr_memo_note_modifications, 81
MTS, 21, 54, 58, 104, 114, 130, 149, 159, 213
multi-column, 49
multi-source, 34
multi-threaded, 34, 54
multi-threaded slave, 4, 6, 18, 27, 34, 37, 49, 159, 226
multiple files, 104
multiple PK columns, 58
multi_range_count, 159
mutex, 42, 58, 69, 94
mutex deadlock, 21
mutexes, 159
mutex_spin_wait, 81
MyISAM, 29, 81, 197, 213
myisamchk, 197
myisampack, 213
myisam_sort_buffer_size, 197
myisam_use_mmap, 213
mysql, 260
mysql client, 104, 149
MySQL Enterprise Monitor, 104
mysql-log-rotate, 226
mysql-systemd-start, 34
mysql-test-run.pl, 15
mysql.master_slave_info, 226
mysql.slave_master_info, 174
mysql.slave_relay_log_info, 174
mysql.slave_worker_info, 226
mysqlaccess, 4, 69
mysqladmin, 29, 37, 58, 104, 130, 149, 197, 248, 260
mysqladmin status, 197
mysqlbinlog, 4, 15, 21, 37, 46, 49, 54, 58, 75, 81, 104, 114, 130, 159, 174,
197, 213, 226, 248, 260, 270
mysqlbinlog --verbose --verbose, 174
mysqlbinlog --version, 114
mysqlbug, 65
mysqlcheck, 114, 226, 260
mysqld, 49, 88, 104, 197
mysqld options, 140
mysqld.1.err, 75
mysqldump, 4, 6, 18, 49, 54, 58, 65, 75, 88, 94, 104, 114, 130, 140, 159,
174, 197, 213, 248, 260, 270
mysqld_multi, 18
287
MySQL 5.6 Release Notes
mysqld_safe, 6, 11, 15, 114, 149, 174, 197, 213, 226
mysqld_safe.pid, 6
mysqlhotcopy, 58, 159, 197
mysqlimport, 29, 260
mysqlshow, 260
mysqlslap, 34, 174, 226, 248, 270
mysql_affected_rows(), 226
mysql_config, 37, 49, 69, 114
mysql_config_editor, 11, 37, 58, 114, 140, 174
mysql_convert_table_format, 69
mysql_find_rows, 69
mysql_firewall_trace, 37
mysql_fix_extensions, 69
MYSQL_HISTIGNORE, 149
mysql_install_db, 49, 69, 75, 114, 140, 149, 174, 213
mysql_kill(), 140
mysql_list_fields(), 226
mysql_load_plugin(), 130, 226
mysql_load_plugin_v(), 130
mysql_options(), 6, 21, 24, 81, 174
mysql_options4(), 174
MYSQL_OPT_RECONNECT, 58
mysql_plugin, 75, 149, 213, 226
mysql_real_connect(), 16, 42, 88
mysql_secure_installation, 6, 149, 159
mysql_setpermission, 49, 69
mysql_stmt_close(), 4
mysql_stmt_errno(), 4
mysql_stmt_error(), 4
mysql_stmt_execute(), 24, 174
mysql_stmt_send_long_data(), 226
mysql_stmt_sqlstate(), 4
mysql_stmt_store_result(), 69
mysql_store_result(), 174
mysql_thread_id(), 140
mysql_upgrade, 27, 81, 94, 104, 114, 140, 159, 174, 213, 226
mysql_use_result(), 174
mysql_waitpid, 65
mysql_zap, 65
my_charset_filename, 94
my_load_defaults(), 104
my_print_defaults, 37
m_ordered_rec_buffer, 159
N
NAME_CONST(), 16
NDB Cluster, 174
net_buffer_length, 226
NO_BACKSLASH_ESCAPES, 197
NO_ZERO_DATE, 69, 174
NO_ZERO_IN_DATE, 69, 174
NULL, 104, 130, 197, 226
NUMA, 27, 29
288
MySQL 5.6 Release Notes
O
off-page storage, 65
old_buf_free, 88
old_lsn, 88
OLD_PASSWORD(), 49, 159
old_passwords, 159
online ALTER TABLE, 88, 114
online DDL, 15, 27, 69
ONLINE_INDEX_ABORTED_DROPPED, 46
OpenBSD, 248
OpenSSL, 4, 6, 11, 14, 18, 21, 24, 34, 46, 49, 58, 68, 114, 130, 159,
174
open_files_limit, 94
optimization, 54, 248
OPTIMIZE, 21, 140
OPTIMIZE TABLE, 42, 65, 69, 213, 248
optimizer, 4, 6, 11, 18, 21, 24, 27, 29, 34, 37, 42, 46, 49, 54, 58,
65, 69, 75, 81, 88, 94, 104, 114, 130, 140, 149, 159, 174, 197, 213, 226, 248,
260, 270
optimizer trace, 213
optimizer_search_depth, 270
optimizer_switch, 69, 248, 260
options, 6, 15, 29, 37, 69, 104, 114, 226, 248
OPT_CHECK_ORDER_BY, 94
Oracle Linux, 58
orphan table, 88
OS X, 29, 197, 226
os-file_pread, 46
os_file_pwrite, 46
os_thread_get_curr_id, 75
OS_THREAD_SLEEP, 104
OUTER JOIN, 248
outer queries, 149
O_DIRECT, 21, 34, 81
P
packaging, 4, 6, 11, 14, 18, 21, 24, 27, 29, 34, 37, 42, 46, 49, 54,
58, 65, 81, 94, 104, 114, 130, 159, 197, 248
Packaging, 29
page, 49, 54
page cleaner, 54
page flushing, 104
page reorganize, 104
page size, 27
pages_free, 114
PAGE_FREE, 149
page_hash lock, 114
page_zip_available, 104
page_zip_decompress, 94
page_zip_validate, 94
parallelism, 94
parent table, 58
parser, 11, 18, 34, 58, 69, 75, 81, 114, 130, 140, 149, 226, 248
289
MySQL 5.6 Release Notes
partition, 27, 69
PARTITION BY KEY, 149
PARTITION BY KEY ALGORITHM, 114
PARTITION BY LIST, 88
PARTITION BY RANGE, 114
partition pruning, 114, 149, 159
partition selection, 197, 248
Partitioning, 21, 29, 34, 37, 42, 46, 49, 54, 58, 69, 75, 81, 88, 94, 104,
114, 130, 140, 149, 159, 174, 197, 213, 226, 248, 270
PARTITION_COMMENT, 174
PASSWORD, 213
PASSWORD(), 49, 159
password_expired, 174
performance, 69, 88, 94, 213
Performance, 94, 114, 130, 140, 159, 174, 197, 213, 226, 248
Performance Schema, 6, 11, 16, 18, 21, 24, 27, 29, 34, 37, 42, 49, 58,
69, 75, 81, 88, 94, 104, 114, 130, 140, 149, 159, 174, 197, 213, 226, 248, 260,
270
performance_schema, 174
performance_schema_max_digest_length, 34
perror, 226
persistent statistics, 65, 88
phrase search, 42
pluggable authentication, 6, 21, 42, 49, 104, 114, 130, 213, 248
plugin API, 226
plugin services, 248
plugins, 6, 11, 18, 21, 27, 29, 42, 54, 58, 69, 88, 94, 104, 130, 197,
213, 226
PLUGIN_DIR, 213
plugin_dir, 226
Port, 197
prepared statements, 6, 15, 16, 21, 24, 27, 37, 54, 65, 81, 88, 104, 114,
130, 149, 159, 197, 226
prepare_commit_mutex, 94
Previous_GTIDs_log_event, 104
Previous_gtid_event, 65
primary key, 88, 104
PRIMARY KEY, 149, 174
primary keys, 174, 213
printf, 75
priority queue, 75
privileges, 6, 18, 21, 27, 29, 37, 42, 49, 58, 69, 75, 81, 88, 94, 104,
114, 130, 149, 159, 213, 226
procedure, 49
PROCEDURE ANALYSE, 174
PROCEDURE ANALYSE(), 29, 226
PROCESSLIST_STATE, 69
process_arithmetic_command, 42
profiling, 149
profiling_history_size, 149
PROXY, 248
pruning, 94
pseudo-slave mode, 130
purge, 46, 54, 69, 88
290
MySQL 5.6 Release Notes
PURGE BINARY LOGS, 58, 104
purge thread, 29, 69
push_warning_printf, 46
P_S.threads, 69
Q
Queries per second, 197
query cache, 4, 37, 54, 114, 140, 149, 174, 197
query log events, 130
query performance, 94
query_alloc_block_size, 27
query_cache_min_res_unit, 29
quotation mark, 58
QUOTE(), 6
R
race condition, 94, 104
RAND(), 174
RANDOM_BYTES(), 69
range, 94
Range checked for each record, 149
raw device, 75
RBR, 11, 49, 54, 58, 88, 104, 114, 159, 174, 213, 248
rbt_search, 49
READ COMMITTED, 29, 54
read-ahead, 260
read-only, 88
read-write lock, 58
readline, 197
readme, 75
read_only, 4
read_rnd_buffer_size, 37
rebuild, 69
REBUILD PARTITION, 81
receiver thread, 37
record format, 197
recovery, 29, 46, 54, 58, 75, 81, 88, 104
recv_writer, 104
redo log, 46, 49, 58, 81
redo log scan, 104
refactoring, 94, 159
REGEXP, 34
regression, 94
regular expressions, 34
relay log, 49, 114, 140, 159, 174
relay log index, 149
relay log recovery, 18
relay log rotation, 29, 54, 65
relay logs, 174
relay-log-info-repository, 88
relaylog.log_lock, 18
relay_log_basename, 248
RELAY_LOG_FILE, 248
291
MySQL 5.6 Release Notes
relay_log_info_repository, 69, 159, 248
relay_log_purge, 174
relay_log_recovery, 174
remote connections, 114
RENAME, 42
RENAME TABLE, 75, 104, 114
RENAME USER, 174
REORGANIZE PARTITION, 197
REPAIR TABLE, 65, 140, 159, 226
REPLACE, 21
REPLACE ... SELECT, 197
REPLACE INTO, 29
replace utility, 49
replicate-rewrite-db, 213
Replication, 4, 6, 11, 15, 16, 18, 21, 24, 27, 29, 34, 37, 42, 46, 49,
54, 58, 65, 69, 75, 81, 88, 94, 104, 114, 130, 140, 149, 159, 174, 197, 213,
226, 248, 260, 270
REPLICATION CLIENT, 174
replication filters, 81
replication info tables, 140
repositories, 197
reservation, 37
RESET MASTER, 104
RESET SLAVE, 159, 226, 270
resolve_stack_dump, 27
resource usage, 69, 159
restarts, 46, 104, 174, 197
result cache, 69
Retrieved_Gtid_Set, 29, 130
REVOKE, 81, 149, 174
rollback, 34, 46, 75, 81, 88, 104, 114, 260
ROLLBACK TO SAVEPOINT, 29
ROLLUP, 94, 114, 159
ROUND(), 213
row event corruption, 75
row format, 16, 18
row images, 248
row size, 46
row-based, 11
row0log.cc, 88
Rows_query_log_events, 174
ROW_FORMAT, 42, 88, 174
row_merge_read_clustered_index, 114
row_upd_changes_ord_field_binary, 69
row_vers_impl_x_locked_lowx, 69
RPAD(), 54, 174
rpl_recover_rank, 270
rpl_semi_sync_master_enabled, 81
rpl_semi_sync_master_timeout, 94
rpl_semi_sync_master_wait_no_slave, 81
Rpl_semi_sync_master_yes_tx, 75
Rpl_status, 270
rpl_stop_slave_timeout, 94
rpl_tblmap.cc, 94
292
MySQL 5.6 Release Notes
RPM, 130
rw_lock_x_lock_func_nowait, 75
S
savepoint, 42, 81
SBR, 104, 174, 197, 213, 226
scalability, 75
scans, 140
schema mismatch, 27, 34
scope, 49
secondary index, 54, 69, 94
Seconds_Behind_Master, 46, 75, 140
secure_auth, 159, 197
secure_file_priv, 14
Security Enhancement, 213
Security Fix, 4, 6, 11, 14, 18, 21, 24, 34, 58, 68, 226, 248, 270
SEC_TO_TIME(), 114
segmentation fault, 49, 69, 75
SELECT, 94, 159, 197, 248
SELECT ... FOR UPDATE, 248
semaphore wait, 104
semi-joins, 174
semisynchronous, 11, 37, 54, 58, 69, 88, 104, 130, 174
semisynchronous replication plugin, 75
server activity counter, 54
server ID, 75
server options, 270
server startup timeout, 104
server variables, 140
server version, 114
server_uuid, 16, 54, 270
set, 37, 42, 94
SET, 114
SET OPTION, 174
SET PASSWORD, 81
SET TRANSACTION, 197
SET type, 104
set-gtid-purged, 104
SHA1(), 174
sha256_password, 159
SHOW AUTHORS, 149
SHOW BINARY LOGS, 174
SHOW BINLOG EVENTS, 174
SHOW COLUMNS, 114
SHOW CONTRIBUTORS, 149
SHOW CREATE DATABASE, 260
SHOW CREATE TABLE, 114
SHOW CREATE TRIGGER, 248
SHOW ENGINE INNODB STATUS, 11, 37, 75, 81
SHOW EVENTS, 226
SHOW INDEX, 88
SHOW MASTER LOGS, 174
SHOW NEW MASTER, 248
293
MySQL 5.6 Release Notes
SHOW PRIVILEGES, 248
SHOW PROCESSLIST, 58, 213
SHOW PROFILE, 140, 159, 248
SHOW PROFILES, 159
SHOW SLAVE HOSTS, 197
SHOW SLAVE STATUS, 29, 69, 75, 94, 130, 140, 174, 226, 260, 270
SHOW STATUS, 34, 104, 226, 248
SHOW TABLE STATUS, 65
SHOW TABLES, 174
SHOW VARIABLES, 114
SHOW WARNINGS, 226
show_old_temporals, 42
shutdown, 29, 34, 37, 42, 49, 69, 75, 88, 130
shutdown hang, 94
shutdown timeout, 104
SIGHUP, 65, 197
signal, 37
SIGPIPE, 174
skip-slave-start, 88
skipped events, 29
slave, 16
slave connections, 114
slave error, 42
slave I/O thread, 140
slave log tables, 174
slave options, 114
slave reconnection, 104
slave SQL thread, 69, 140
slave-skip-errors, 226
slave_allow_batching, 174
slave_master_info, 104, 159, 226, 248
slave_max_allowed_packet, 104
slave_net_timeout, 130
Slave_open_temp_tables, 65
slave_parallel_workers, 159, 174, 226
slave_pending_jobs_size_max, 4, 104
slave_relay_log_info, 104, 159, 226, 248
slave_transaction_retries, 226
slave_type_conversions, 94
slave_worker_info table, 159
slow shutdown, 46
slow_query_log, 174
Solaris, 69, 114, 140, 159
sort buffer, 24
sorting, 75
space character, 149
space ID, 58
SPACE(), 213
spatial functions, 226
SQL functions, 140
sql/sql_base.cc, 58
SQL_AFTER_GTIDS, 88, 174
SQL_AFTER_MTS_GAPS, 174
SQL_BEFORE_GTIDS, 174
294
MySQL 5.6 Release Notes
SQL_BUFFER_RESULT, 159
sql_log_bin, 49
sql_mode, 69
sql_slave_skip_counter, 130
SQL_THREAD_WAIT_AFTER_GTIDS(), 149, 159
srv_file_check_mode, 75
SRV_FORCE_NO_TRX_UNDO, 81
srv_master_thread, 88
srv_max_n_threads, 81
srv_read_only_mode, 114
SSH, 213
SSL, 4, 6, 11, 14, 18, 21, 24, 29, 46, 54, 159, 226
Ssl_cipher_list, 226
Ssl_server_not_after, 226
Ssl_server_not_before, 226
Ssl_verify_server_cert, 226
stack size, 6
stall, 21
standard monitor, 75
START SLAVE, 65, 88, 114, 130, 159, 174, 197, 213, 270
START SLAVE IO_THREAD, 81
START SLAVE UNTIL, 88, 174
START TRANSACTION, 88, 197
startup, 24, 58, 75, 197
Start_log_event_v3, 49
start_time, 75
statistics, 11, 65, 94
status variables, 114, 270
STOP SLAVE, 21, 65, 81, 114, 159, 174, 197, 248, 260, 270
STOP SLAVE IO_THREAD, 81
storage engines, 58, 149, 174, 197, 226
stored functions, 197
stored procedures, 24, 29, 37, 65, 88, 104, 114, 197, 226
stored program, 65
stored programs, 15, 18, 130, 140, 149, 159, 174, 197, 213, 226
stored routines, 88, 130, 140, 149, 197
stored_program_cache, 197
STRAIGHT_JOIN, 197
strict mode, 37
ST_Contains(), 149, 159
ST_Difference(), 149
ST_Equals(), 149
ST_Within(), 149
subpartitions, 29, 197
subqueries, 197, 260
SUBSTRING_INDEX(), 197
SUPER, 174
symbolic links, 140
sync, 54
sync_array_cell_print, 114
sync_binlog, 69
system tables, 140
system tablespace, 27, 69
system variables, 270
295
MySQL 5.6 Release Notes
SYS_DATAFILES, 75
SYS_INDEXES, 49
SYS_TABLES, 42
T
table, 46
table cache, 46
table handler, 88
table lock, 18
table map events, 226
Table Monitor, 65
table monitor, 75
table name, 29
table statistics, 75
TABLE::key_info, 114
tablespace, 46, 49, 75, 88, 94, 104
tablespace files, 21
tablespace monitor, 75
table_open_cache, 174
Table_open_cache_hits, 174
table_open_cache_instances, 174
Table_open_cache_misses, 174
Table_open_cache_overflows, 174
TABLE_ROWS, 65
tcmalloc, 18
temporary files, 54
temporary table, 24, 42, 49
temporary tables, 16, 24, 58, 75, 130, 159, 197, 226, 260
test suite, 4, 16, 21, 37, 46, 174
thread cache, 149
thread concurrency, 94
thread locking, 58
thread pool plugin, 6, 81, 88, 94, 114
thread stack overflow, 104
threadpool plugin, 42
Threads_running, 159
thread_concurrency, 54, 260
thread_pool_high_priority_connection, 104
timed_mutexes, 58
timeouts, 149
TIMESTAMP, 58, 114, 174, 197, 248
TLS, 213
tmpdir, 24, 69
tmpfs, 81
token size, 24
TO_BASE64(), 260
TO_DAYS(), 114
transaction log, 81
transactional tables, 29
transactions, 54, 58, 65, 69, 94, 130, 149, 159, 174, 197, 226, 260
transaction_prealloc_size, 42
triggers, 29, 58, 65, 197, 226
TRUNCATE, 42, 46
296
MySQL 5.6 Release Notes
TRUNCATE TABLE, 34, 65, 75, 81, 94
trx->fts_trx, 81
trx_free_for_background(), 104
trx_rollback_or_clean_recovered(), 104
trx_rollback_resurrected(), 104
type conversions, 130
types, 248
U
UBSAN, 6
ucs2_unicode_520_ci, 159
ULN, 130
UMASK, 140
undo log, 88
undo tablespace, 6, 88
Unicode, 248, 260
uninstall, 69
UNION, 65, 114, 130, 248
UNIQUE INDEX LOCK, 104
unique keys, 174
unique secondary index, 54
UNIV_DEBUG, 104
UNIV_LOG_DEBUG, 88
UNIV_SYNC_DEBUG, 75, 104
UNIX_TIMESTAMP(), 226
unsafe statements, 197
unsigned_flag, 270
UPDATE, 46, 69, 226, 248
updates, 104
UpdateXML(), 130, 159, 260
Update_rows_log_event, 104
UPDATE_TIME, 37
upgrades, 46, 65, 75, 130, 159, 174, 197
upgrades and downgrades, 114
uppercase, 49
USE, 149, 248
USER, 213
user variables, 104, 114, 174
user-defined variables, 159
username, 149
UTF-16LE, 260
UTF-8, 42
UTF-8 table name, 94
utf16le, 260
UUIDs, 16, 130, 270
V
Valgrind, 24, 27, 94, 104, 114, 130, 140, 159, 174, 197, 213, 226, 248
validate_password plugin, 29, 34, 49, 104, 130
validate_password_dictionary_file, 34, 130
validate_password_dictionary_file_last_parsed, 34
validate_password_dictionary_file_words_count, 34
VALIDATE_PASSWORD_STRENGTH(), 159
297
MySQL 5.6 Release Notes
VALUES IN (NULL), 88
VALUES(), 104, 114
VARCHAR, 197
variable scope, 114
variables, 94
versions, 69, 114
version_compile_machine, 149, 174
views, 29, 58, 75, 114, 130, 149, 159, 174, 197, 226, 260
Visual C++ Redistributable, 6
Visual Studio, 69
W
Warning 1292, 197
warnings, 69, 149, 159, 197, 213
WEEK, 248
WEIGHT_STRING(), 159, 270
WHERE, 94
whitespace, 4
WITH CONSISTENT SNAPSHOT, 88
Within(), 159
WITH_LIBWRAP, 114
WITH_SSL, 149, 159, 174
worker threads, 94
write locks, 37, 42
X
x86_64, 270
XA, 46, 104, 114, 159, 226
XA COMMIT, 226
XA PREPARE, 37
XA transactions, 174, 226
XML, 6, 75, 81, 130, 159, 248
XML functions, 21
XPath, 75, 130
Y
yaSSL, 14, 24, 29, 37, 46, 49, 54, 69, 114, 130, 174
YEAR, 174
Z
zip_mutex, 69
zlib, 226
298
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