Oracle Database 11g Manageability Overview

Oracle Database 11g Manageability Overview
Oracle Database 11g:
Manageability Overview
An Oracle White Paper
August 2007
Oracle Database 11g:
Manageability Overview
Introduction ....................................................................................................... 3
Manageability ..................................................................................................... 3
ADDM for RAC........................................................................................... 3
Automatic SQL Tuning ............................................................................... 4
SQL Plan Management ................................................................................ 5
SQL Access Advisor Enhancements: Partition Advisor......................... 6
Automatic Memory Management............................................................... 7
AWR Baselines and Adaptive Thresholds ................................................ 8
Fault Diagnostic Infrastructure................................................................. 10
Health checks.......................................................................................... 10
Data Recovery Advisor ......................................................................... 10
SQL Repair Advisor............................................................................... 11
SQL Test Case Builder .......................................................................... 11
Automatic Diagnostic Repository (ADR) .......................................... 11
Incident packaging service (IPS).......................................................... 11
Support Workbench ................................................................................... 12
Conclusion........................................................................................................ 13
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Oracle Database 11g:
Manageability Overview
The Oracle database is the market-leader and the preferred database for hundreds
of thousands of enterprises as well as application developers and database
administrators worldwide. Over the years, enterprises have come to rely on the
Oracle database to provide unparalleled performance and reliability. In release 10g
of the database, Oracle delivered a self-managing database with breakthrough
manageability, dramatically reducing management costs. In this release, Oracle
Database 11g has made significant advances in the areas of fault diagnostics to
reduce time to diagnosis and resolution and improving the availability and
reliability of your mission critical databases. Oracle has also continued to make
major improvements in all manageability aspects of the database making Oracle
11g Database more self-managing than ever before.
Oracle Database 10g introduced Automatic Database Diagnostic Monitor
(ADDM), which was a revolutionary feature that helped create the first selfmanaging database. ADDM uses an integrated approach to provide database-wide
performance analysis, which covered storage, system resource, space, application &
SQL and backup & recovery management. It provides proactive analysis to DBAs
and is available on demand to troubleshoot performance problems.
Oracle Database 11g extends ADDM by offering cluster-wide performance
analysis for Real Application Clusters (RAC) databases. For RAC environments
ADDM analyses the RAC cluster and reports on issues that are affecting the entire
database as well as its individual instances. DBAs can now use ADDM to perform
database-wide analysis of global resources, such as high-load SQL, global cache
interconnect traffic, network latency issues, skew in instance response times, I/O
capacity, etc. DBAs also have the ability to restrict ADDM analysis on a few
specified instances of a RAC cluster as well. With ADDM for RAC, performance
analysis of a RAC database becomes as simple as that of a single instance database.
In Oracle Database 11g, ADDM findings can be suppressed by DBAs using
directives to filter and display only findings of interest. To better understand the
Oracle Database 11g: Manageability Overview
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impact of the findings over time, each finding has a descriptive name that
facilitates search, a link to the number of previous occurrences of the finding in
last 24 hours, and affected instances.
Automatic SQL Tuning
Poor SQL performance is a common cause of badly performing databases. Many
DBAs have traditionally tried to tackle this using manual SQL tuning processes.
Manual SQL tuning is a complex and recurring process that presents many
challenges. It is very time consuming, and requires an intimate knowledge of the
schema structures and the data usage model of the application and query plans. All
these factors make manual SQL tuning a challenging and resource intensive task
that is ultimately very expensive for businesses.
SQL Tuning Advisor was introduced in Oracle 10g to automate the SQL tuning
process by comprehensively analyzing SQL statements. The output of this analysis
is in the form of recommendations, along with a rationale for each
recommendation and its expected performance benefit. The recommendation
relates to collection of statistics on objects, creation of new indexes, restructuring
of the SQL statements, or creation of SQL Profiles. A user can review the
recommendations and implement them manually as appropriate.
In Oracle Database 11g, the SQL tuning process has been further enhanced and
automated to keep databases running at their peak performance. The SQL Tuning
Advisor now runs automatically during the system maintenance windows as a
maintenance task. In each run, it auto-selects high-load SQL queries in the system,
and generates recommendations on how to tune them.
To validate the recommendation, SQL Tuning Advisor in Oracle Database 11g
performs a test-execute of the SQL statements with the new execution plan for
which a SQL Profile is recommended. This dramatically increases the accuracy and
reliability of SQL Profile recommendations.
Automatic SQL Tuning Advisor can be configured to auto-implement SQL Profile
recommendations. If you enable automatic implementation, the advisor will create
SQL Profiles for only those SQL statements, where the performance improvement
would be at least three-fold. Other types of recommendations, such as the ones to
create new indexes or refresh optimizer statistics or the ones that restructure SQL,
can only be implemented manually. DML statements are not considered for tuning
by Automatic SQL Tuning Advisor. By default, the Automatic SQL Tuning
Advisor is configured to run nightly and only report recommendations but not
auto implement them.
You can view a summary of the results of automatic SQL tuning over a specified
period (such as the previous seven days), as well as view a detailed report on
recommendations made for all SQL statements processed. The recommendations
can then be selectively implemented by a manual process. You can also view the
recommendations that were automatically implemented. The Automatic SQL
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Tuning Advisor can be configured to run in any maintenance window or can be
disabled altogether if desired.
SQL Plan Management
SQL plan management prevents performance regressions resulting from sudden
changes to the execution plan of a SQL statement by providing components for
capturing, selecting, and evolving SQL executions plans. SQL performance can be
affected by various changes, such as new optimizer version, changes to optimizer
statistics and/or parameters, or creation of SQL profiles. SQL plan management is
a preventative mechanism that records and evaluates the execution plans of SQL
statements over time, and builds SQL plan baselines composed of a set of existing
plans known to be efficient. The SQL plan baselines are then used to preserve
performance of the corresponding SQL statements, regardless of changes
occurring in the system.
Common usage scenarios where SQL plan management can improve or preserve
SQL performance include:
A database upgrade that installs a new optimizer version usually results in plan
changes for a small percentage of SQL statements, with most of the plan
changes resulting in either improvement or no performance changes.
However, certain plan changes may cause performance regressions. The use of
SQL plan baselines significantly minimizes potential performance regressions
resulting from a database upgrade.
Ongoing system and data changes can impact plans for some SQL statements,
potentially causing performance regressions. The use of SQL plan baselines
can also help to minimize performance regressions and stabilize SQL
Deployment of new application modules means introducing new SQL
statements into the system. The application software may use appropriate SQL
execution plans developed under a standard test configuration for the new
SQL statements.
SQL plan baselines evolve over time to produce better performance. During the
SQL plan baseline evolution phase, Oracle Database 11g routinely evaluates the
performance of new plans and integrates plans with better performance into SQL
plan baselines. A successful verification of a new plan consists of comparing its
performance to that of a plan selected from the SQL plan baseline and ensuring
that it delivers better performance.
There are three ways of evolving SQL plan baselines:
Manually by loading new plans verified by the user into existing SQL plan
Manually by using the EVOLVE_SQL_PLAN_BASELINE function of the
DBMS_SPM PL/SQL package to verify new plans.
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Automatically using the Automatic SQL Tuning capabilities of Oracle
Database 11g.
SQL Access Advisor Enhancements: Partition Advisor
SQL Access Advisor has been enhanced in Oracle Database 11g to provide
partition advice as a part of SQL access structure recommendations. The new and
improved SQL Access Advisor now gives comprehensive advice on how to
optimize schema design for best performance based on the system workload. The
SQL Access Advisor takes in actual or synthetic SQL workloads as input and
recommends access structures for improved performance. The recommended
access structures include partitioning recommendations for tables and indexes, and
materialized views as well as recommendations to create new or drop existing
indexes (b-tree, bitmap, and functional indexes), materialized views and
materialized view logs. SQL Access Advisor considers both queries and DML
when offering recommendations.
The partition recommendations are only provided for workloads have some
predicates and joins on columns of type NUMBER or DATE. Partitioning advice
is only generated on the above column types and is restricted to a single column
INTERVAL, HASH or RANGE partitioning. The SQL Access Advisor is
sophisticated enough to identify candidates for partition and suggest partition keys
and ranges for the above kinds of partitions.
Similar to SQL Tuning Advisor, SQL Access Advisor leverages the existing CostBased Optimizer (CBO) rules and is an easy-to-use wizard based solution. Because
of the tight integration between SQL Access Advisor and the database kernel, the
advisor makes the optimal recommendation for access structures based on the
updated CBO rules that the kernel ships with.
SQL Access Advisor can also make recommendations for a combination of index,
materialized view and partitioning solution. The factors that are considered when
making SQL Access Advisor recommendations include storage (for creation and
maintenance costs), whether workloads are full or partial and the overall benefit to
the queries in the workload.
When processing large workloads, SQL Access Advisor can be interrupted and will
offer intermediate recommendations for the set of SQL that have been processed
thus far. The order in which SQL are processed by the SQL Access Advisor can be
configured by the user.
Oracle Enterprise Manager displays the results of the SQL Access Advisor task by
listing SQL statements in the order of highest cost improvement. DBAs have the
option of executing the recommendation right away at the touch of a button. Or,
in more stringent environments, DBAs can create a script with the set of
executable SQL statements to implement the recommendations.
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Automatic Memory Management
Oracle Database memory structures basically consist of shared memory or System
Global Area (SGA) and private memory or Program Global Area (PGA). In
Oracle Database 9i, Automatic SQL Execution Memory Management feature was
introduced to automate management of PGA. In Oracle Database 10g, the same
was done for SGA by the introduction of Automatic Shared Memory
Management. This meant all the different SQL areas in PGA were auto-sized for
the system workload to give best performance and all the memory pools in shared
memory were similarly adjusted for size for optimal performance. The user was
only required to specify the PGA and SGA target sizes and Oracle would
appropriately allocate memory within these targets to give the best possible
performance. PGA and SGA Advisors were also provided to help the user
properly set the targets for SGA and PGA in Oracle Database 10g.
O /S M em ory
O /S M em ory
Figure 1: Automatic Memory Management
In Oracle Database 11g, memory management has been automated even further.
All memory, PGA and SGA, is now managed centrally with the help of the
Automatic Memory Management feature. DBAs need to specify a single
parameter, MEMORY_TARGET, and Oracle will automatically size the Program
Global Area (PGA) and System Global Area (SGA) based on the workload. Using
indirect memory transfer, the database transfers memory from SGA to PGA and
vice versa to respond to the load. The indirect transfer uses the operating system
mechanism to free up shared memory and allocating memory to other components
requesting memory, e.g., from PGA to SGA. Dynamic allocation of memory is
adjusted at frequent intervals to optimize memory usage in line with workload
requirements to maximize memory utilization and avoid out-of-memory errors.
Users can optionally set SGA and PGA targets when using the Automatic Memory
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Management feature. This ensures that SGA and PGA sizes will not be shrunk
below the values specified by their respective parameter targets in auto-tuning
mode. This feature is currently available in Linux, Solaris, HP-UX, AIX and
Windows platforms.
First introduced in Oracle Database 10g, Memory Advisors provide graphical
analyses of total memory target settings, SGA and PGA target settings, or SGA
component size settings. DBAs can use these analyses to tune database
performance and to perform what-if planning scenarios. Different memory
advisors become available depending on the memory management mode used with
the database.
For instance, if Automatic Memory Management is enabled, you can get advice for
setting the target amount of memory to allocate to the entire database. This
advisor provides advice for the total memory target for the instance. If Automatic
Shared Memory Management is enabled, you can gain advice on configuring the
target sizes of the SGA and instance PGA. If Manual Shared Memory
Management is enabled, you can get advice on sizing the shared pool, buffer cache,
and instance PGA.
AWR Baselines and Adaptive Thresholds
Automatic Workload Repository (AWR) was one the most prominent selfmanaging features of Oracle Database 10g. The Oracle Database captures real-time
and historical performance statistics in memory and in the database respectively to
give DBAs the right tools and information troubleshoot performance problems.
AWR Baselines allow DBAs to capture system performance over time periods with
interesting or representative workloads. For example, if a company’s current
month payroll processing was slow, then the DBA can compare the system
performance with last month’s payroll processing to identify causes for the
The AWR Compare Periods report is provided to easily make comparisons of
problem time periods against saved Baselines to identify potential sources of
performance deviations. In addition to performance metrics, the report also
captures the configuration information, such as the total memory, and number of
CPUs, which can identify external sources of problems that may have caused the
reduction in performance. In case there were out-of-band changes made to critical
parameters, such as COMPATIBLE, which may affect SQL performance, the
report also captures database system information, such as the initialization
In addition Baselines can also be used in setting alert thresholds on system
performance metrics. Most metrics can be viewed in Oracle Enterprise Manager
against statistical aggregates of those same metrics observed over the Baseline
period. This helps users set Baseline-informed thresholds rather than selecting
thresholds without the context of actual data. In addition, Adaptive Thresholds are
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available for certain key performance metrics. Adaptive Thresholds are
performance alert thresholds that are automatically set and periodically adjusted by
the system using the System Moving Window Baseline data as the basis for
threshold determination. For customers who want to get started with Adaptive
Thresholds immediately, the new “Quick Configure” option can setup a starter kit
of thresholds based on common workload profiles using a few mouse clicks.
There are three types of available baselines in Oracle Database:
Fixed Baselines
A fixed baseline corresponds to a fixed, contiguous time period in the past
specified by the user. Typically the time period chosen as baseline should
represent the system operating at an optimal level so that during periods of
poor performance, comparison can be made to the baselines to analyze causes
of performance degradation.
System Moving Window
The System Moving Window is available out-of-box and defined to be all
AWR data available extending from the present back a specified window size
into the past (expressed as number of days). By default this window size is the
current AWR retention period, which is 8 days. If you are planning to use
Adaptive Thresholds consider a larger moving window (such as 35 days) to
compute better threshold values over larger data samples. The System Moving
Window size can be configured to be less than AWR retention in cases where
customers set the latter to be very large. As a general rule the System Moving
Window should optimally be between 3 and 13 weeks in size.
Baseline Templates
You can also create baselines for a contiguous time period in the future using
baseline templates. There are two types of baseline templates, single and
repeating. A single baseline template can be used to create a baseline for a
single contiguous time period in the future. This is useful if you know
beforehand of a time period that you want to capture in the future. For
example, you may want to capture the AWR data during a system test that is
scheduled for the upcoming weekend. In this case, you can create a single
baseline template to automatically capture the time period when the test will
take place.
A repeating baseline template can be used to create and drop baselines based
on a repeating time schedule. This is useful if you want the Oracle database to
automatically capture a contiguous time period on an ongoing basis. For
example, you may want to capture the AWR data during every Monday
morning for a month. In this case, you can create a repeating baseline template
to automatically create baselines on a repeating schedule for every Monday,
and automatically remove older baselines after a specified expiration interval
such as one month.
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AWR baselines provide powerful capabilities for defining dynamic and future
baselines and considerably simplify the process of creating and managing
performance data for comparison purposes.
Fault Diagnostic Infrastructure
Beginning with Release 11g, Oracle Database includes an advanced fault diagnostic
infrastructure for preventing, detecting, diagnosing, and resolving problems. The
problems that are targeted in particular are critical errors that can affect the health
of the database. When a critical error occurs, it is assigned an incident number, and
diagnostic data for the error (traces, dumps, and more) are immediately captured
and tagged with this number. The data is then stored in the Automatic Diagnostic
Repository (ADR)—a file based repository outside the database—where it can
later be retrieved by incident number and analyzed. The extensive improvement of
the fault diagnostics infrastructure in Oracle Database 11g aims to provide the
following benefits:
Respond proactively to small problems and prevent catastrophic system failure
by alerting DBAs using Health Checks.
Limiting damage and repair and interruptions after a problem is detected using
Data Recovery and SQL Repair Advisor.
Reducing problem diagnostic time through ADR and Test Case Builder.
Simplifying customer interaction with Oracle Support using IPS and Oracle
Configuration Support Manager.
The following are the key components of the fault diagnostic infrastructure:
Health checks
Health checker framework has been added in Oracle Database 11g for the
purposes of performing proactive checks on system health. Upon detecting a
critical error, the fault diagnostic infrastructure can run one or more health checks
to perform deeper analysis of a critical error. The results of a health check are
stored in a report that can be viewed as a text file or as formatted HTML in a
browser. The report can be added to the other diagnostic data collected for the
error. Separate individual health checks look for data corruptions, undo and redo
corruptions, data dictionary corruption, and more. As a DBA, you also have the
option to manually invoke these health checks, either on a regular basis or as
Data Recovery Advisor
You use the Data Recovery Advisor to repair data block corruptions, undo
corruptions, data dictionary corruptions, and more. The Data Recovery Advisor
integrates with the Support Workbench facility in Oracle Enterprise Manager and
with the RMAN utility to display data corruption problems, assess their extent and
impact and recommend repair options for them.
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SQL Repair Advisor
The SQL Repair Advisor is a new feature that helps DBAs diagnose SQL
problems. If a SQL statement fails with a critical error (e.g., an ORA-600 error),
you can use the SQL Repair Advisor to analyze the problem and in many cases it
can recommend a SQL patch to repair the statement. By applying the SQL patch,
the SQL failure is circumvented by causing the query optimizer to choose an
alternate execution plan for future executions.
SQL Test Case Builder
For many application problems, obtaining a reproducible test case is an important
factor in problem resolution speed. The SQL Test Case Builder allows a user to
automatically gather all the necessary information needed to reproduce the
problem such as SQL text, PL/SQL, DDL, execution environment information,
etc. The information gathered can then be transmitted to Oracle Support to help
reproduce the problem.
Automatic Diagnostic Repository (ADR)
The ADR is a file-based repository for database diagnostic data such as traces,
dumps, the alert log, health monitor reports, and more. It has a unified directory
structure across multiple instances and components of the Oracle Database and it
CORE_DUMP_DEST of previous releases. The diagnostic data in ADR is selfmanaging and is purged automatically based on predefined data retention setting.
ADR also maintains meta-data for all critical errors on the database such that a
user can run queries against ADR to determine what and how many critical
problems occurred on the system over the last few days, months or even years.
The data in ADR can be viewed using Oracle Enterprise Manager or through a
command-line utility called ADR Command Interpreter or ADRCI.
Incident packaging service (IPS)
Incident Packaging Service automates the process of collecting all necessary
diagnostic data related to one or more problems. Users no longer have to search in
different directory locations trying to gather all the relevant trace files and dump
files needed for problem diagnosis by Oracle Support. By invoking IPS, all
diagnostic data (traces, dumps, health check reports, SQL test cases, and more)
pertaining to a critical error is automatically packaged into a zip file which can then
be shipped to Oracle Support.
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Figure 2: Incident package details
Support Workbench
The Support Workbench is a facility in Oracle Enterprise Manager that enables
you to interact with the new fault diagnostic infrastructure of Oracle Database 11g.
With it you can investigate, report, and where appropriate, repair problems, all with
an easy-to-use graphical interface. The Support Workbench provides a self-service
means for you to package diagnostic data using IPS, obtain a support request
number, and upload the IPS package to Oracle Support with a minimum of effort
and in a very short time, thereby reducing time-to-resolution for problems. Note
that all automated interactions with Oracle Support, such as support number
creation or IPS package upload, requires Oracle Configuration Manager to be
running at the database location.
Oracle Configuration Support Manager, a proactive automated support capability
included in Oracle Premier Support, offers customers a simpler way to track,
manage, and support your Oracle configurations while reducing the risk of
unplanned system downtime.
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Automatic Diagnostic
Auto Incident Creation
First-Failure Capture
Alert DBA
Targeted Health Checks
EM Support Workbench:
Package Incident &
Configuration Information
Repair Advisors
EM Support Workbench:
Apply Patch or Workaround
Repair Advisors
Figure 3: Support workbench workflow
The Support Workbench workflow consists of the following steps:
Create an incident in the database automatically based on the first occurrence
of a failure.
Alert the DBA of the failure and run health checks in the areas where the
failure was reported.
If it is a known issue, then recommend and apply patch to solve the problem.
Otherwise, package up incidents and relevant configuration information and
upload to Oracle Support and run repair advisors to recover from failure.
There are many different kinds of problems that can occur in an Oracle Database
and the right remedy for each problem may be different. The Support Workbench
has extensive workflows that guide the user to take action that is appropriate for
the problem encountered.
The manageability and diagnosability enhancements in Oracle Database 11g allows
database administrators to keep their systems performant and available, while
providing higher quality of service to their users.
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Oracle Database 11g: Manageability Overview
August 2007
Author: Jagan R. Athreya
Contributing Authors: Mughees Minhas
Oracle Corporation
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