Oracle TimesTen In-Memory Database Operations Guide

Oracle TimesTen In-Memory Database Operations Guide
Oracle TimesTen
In-Memory Database
Operations Guide
Release 6.0
B25269-03
For last-minute updates, see the TimesTen release notes.
Copyright ©1996, 2006, Oracle. All rights reserved.
ALL SOFTWARE AND DOCUMENTATION (WHETHER IN
HARD COPY OR ELECTRONIC FORM) ENCLOSED AND ON
THE COMPACT DISC(S) ARE SUBJECT TO THE LICENSE
AGREEMENT.
The documentation stored on the compact disc(s) may be printed by
licensee for licensee’s internal use only. Except for the foregoing,
no part of this documentation (whether in hard copy or electronic
form) may be reproduced or transmitted in any form by any means,
electronic or mechanical, including photocopying, recording, or
any information storage and retrieval system, without the prior
written permission of TimesTen Inc.
Oracle, JD Edwards, PeopleSoft, Retek, TimesTen, the TimesTen
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The Programs (which include both the software and documentation) contain proprietary information; they are provided under a license agreement containing restrictions on use and disclosure and
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The information contained in this document is subject to change
without notice. If you find any problems in the documentation,
please report them to us in writing. This document is not warranted
to be error-free. Except as may be expressly permitted in your license agreement for these Programs, no part of these Programs may
be reproduced or transmitted in any form or by any means, electronic or mechanical, for any purpose.
March 2006
Printed in the United States of America
TimesTen to TimesTen Replication Guide
Contents
About this Guide
TimesTen documentation . . .
Background reading . . . . .
Installing TimesTen . . . . .
Conventions used in this guide .
Finding the information you need
Technical Support . . . . . .
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2
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7
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Overview . . . . . . . . . . . . . . . .
Before you begin . . . . . . . . . . . .
Lessons . . . . . . . . . . . . . . . .
Lesson 1: Defining a data source name (DSN) . .
Data sources and data stores. . . . . . . .
Defining a DSN on Windows . . . . . . .
Defining a DSN on UNIX . . . . . . . .
Lesson 2: Connecting to a data store . . . . . .
Using ttIsql on Windows . . . . . . . . .
Using ttIsql on UNIX . . . . . . . . . .
Lesson 3: Creating tables . . . . . . . . . .
Lesson 4: Populating the data store using ttBulkCp
Lesson 5: Working with a data store . . . . . .
Lesson 5A: Inserts . . . . . . . . . . .
Lesson 5B: Selects . . . . . . . . . . .
Lesson 5C: Updates . . . . . . . . . . .
Lesson 5D: Deletes . . . . . . . . . . .
Lesson 6: Data store backup . . . . . . . . .
Lesson 7: Destroying a data store . . . . . . .
Using ttStatus . . . . . . . . . . . . .
Using ttDestroy. . . . . . . . . . . . .
Lesson 8: Restoring a data store. . . . . . . .
Other considerations. . . . . . . . . . .
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30
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32
32
1 QuickStart
2 Creating TimesTen Data Stores
TimesTen ODBC and JDBC drivers
TimesTen ODBC drivers . . .
TimesTen JDBC driver . . . .
JDBC driver manager . .
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i
Data source names . . . . . . . . . . . . . . . . .
User and system DSNs . . . . . . . . . . . . . .
Data Manager and Client DSNs . . . . . . . . . .
Connection attributes for Data Manager DSNs. . . . .
Exclusive and shared connections. . . . . . . . . .
Thread programming with TimesTen . . . . . . . .
Creating a DSN on Windows . . . . . . . . . . . . .
Specify the ODBC driver . . . . . . . . . . . . .
Specify the DSN . . . . . . . . . . . . . . . .
Specify the connection attributes . . . . . . . . . .
Creating a DSN on UNIX . . . . . . . . . . . . . .
Create a user ODBC.INI file . . . . . . . . . . . .
Specify the DSN . . . . . . . . . . . . . . . .
Specify the ODBC driver . . . . . . . . . . . . .
Specify the data store path name . . . . . . . . . .
Set data store attributes . . . . . . . . . . . .
Using environment variables in data store path names
DSN examples. . . . . . . . . . . . . . . . . . .
Setting up a temporary data store . . . . . . . . . .
Creating multiple DSNs to a single data store . . . . .
Connecting to a data store without using a DSN . . . .
Specifying the size of a data store . . . . . . . . . . .
Temporary and permanent memory . . . . . . . . .
Changing data store size . . . . . . . . . . . . .
Receiving out-of-memory warnings . . . . . . . . .
Specifying a RAM policy . . . . . . . . . . . . . .
Configuring a diskless data store . . . . . . . . . . .
Copying, migrating, backing up and restoring a data store .
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. 33
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. 55
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3 Working with the TimesTen Client and Server
Client/Server Communication. . . . . . . . .
TCP/IP Communication . . . . . . . . .
Shared memory communication . . . . . .
UNIX domain socket communication . . . .
Configuring TimesTen Client and Server . . . .
Running the TimesTen Server Daemon . . . . .
Server informational messages . . . . . . .
Defining Server DSNs . . . . . . . . . . .
TimesTen Client connection attributes . . . . .
Creating and configuring Client DSNs on Windows
Creating and configuring a logical server name
Creating a Client DSN on Windows . . . . .
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ii Oracle TimesTen In-Memory Database Operations Guide
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Setting the timeout interval and authentication. . . . . . .
Deleting a server name . . . . . . . . . . . . . . . .
Accessing a remote data store on Windows . . . . . . . .
Testing connections . . . . . . . . . . . . . . . . .
Creating and configuring Client DSNs on UNIX . . . . . . .
Searching for a DSN . . . . . . . . . . . . . . . . .
Creating and configuring a logical server name . . . . . .
Examples . . . . . . . . . . . . . . . . . . .
Creating a Client DSN . . . . . . . . . . . . . . . .
Accessing a remote data store on UNIX. . . . . . . . . . .
Testing connections . . . . . . . . . . . . . . . . .
Troubleshooting Client/Server problems . . . . . . . . . .
Cannot connect to theTimesTen Server. . . . . . . . . .
TimesTen Server failed . . . . . . . . . . . . . . . .
Cannot find TimesTen Server DSN . . . . . . . . . . .
TimesTen Server failed to load DRIVER . . . . . . . . .
Application times out when accessing TimesTen Server . . .
TimesTen Client loses connection with TimesTen Server . .
Failed to attach to shared memory segment for IPC . . . . .
Increasing the maximum Server connections on Windows XP
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4 Working with the Oracle TimesTen Data Manager Daemon
Starting and stopping the Oracle TimesTen Data Manager Service on Windows .
78
Starting and stopping the daemon on UNIX . . . . . . . . . . . . . . 79
Managing TimesTen daemon options . . . . . . . . . . . . . . . . . 80
Determining the daemon listening address . . . . . . . . . . . . . 80
Informational messages. . . . . . . . . . . . . . . . . . . . . 81
Modifying the informational message options on Windows . . . . . 81
Modifying the informational message options on UNIX . . . . . . 82
Changing the allowable number of subdaemons . . . . . . . . . . . 82
Diskless operations . . . . . . . . . . . . . . . . . . . . . . 82
Managing TimesTen Client/Server daemon options . . . . . . . . . . . 84
Modifying the TimesTen Server daemon options . . . . . . . . . . . 84
Controlling the TimesTen Server daemon. . . . . . . . . . . . . . 84
Prespawning TimesTen Server processes . . . . . . . . . . . . . . 84
Using shared memory for Client/Server IPC . . . . . . . . . . . . 85
Managing the size of the shared memory segment . . . . . . . . 85
Changing the size of the shared memory segment . . . . . . . . . 86
Controlling the TimesTen Server log messages . . . . . . . . . . . 87
Modifying the TimesTen web server options . . . . . . . . . . . . . . 88
Controlling the TimesTen web server . . . . . . . . . . . . . 88
iii
5 Using the ttIsql Utility
Batch mode vs. interactive mode . . . . . . . . . . . . .
Using ttIsql’s online help . . . . . . . . . . . . . . . .
Using ttIsql’s ‘editline’ feature (UNIX only) . . . . . . . . .
Emacs binding . . . . . . . . . . . . . . . . . . .
vi binding . . . . . . . . . . . . . . . . . . . . .
Using ttIsql’s command history . . . . . . . . . . . . . .
Working with transactions . . . . . . . . . . . . . . . .
Displaying data store information . . . . . . . . . . . . .
Viewing and changing query optimizer plans. . . . . . . . .
Timing ODBC function calls . . . . . . . . . . . . . . .
Working with prepared and parameterized SQL statements . . .
Defining default settings with the TTISQL environment variable .
Managing XLA bookmarks . . . . . . . . . . . . . . .
Handling Unicode characters . . . . . . . . . . . . . . .
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6 Working with Data in a TimesTen Data Store
Data store overview . . . . . . . . . . . . . . . . . . . . . . 118
Data store components . . . . . . . . . . . . . . . . . . . . 118
Data store users and owners . . . . . . . . . . . . . . . . . . 118
Data store persistence . . . . . . . . . . . . . . . . . . . . 119
Understanding tables . . . . . . . . . . . . . . . . . . . . . . 120
In-line and out-of-line columns. . . . . . . . . . . . . . . . . 120
Default column values . . . . . . . . . . . . . . . . . . . . 121
Table names . . . . . . . . . . . . . . . . . . . . . . . . 121
Table access . . . . . . . . . . . . . . . . . . . . . . . . 121
Primary keys, foreign keys and unique indexes . . . . . . . . . . 122
System tables. . . . . . . . . . . . . . . . . . . . . . . . 122
Working with tables . . . . . . . . . . . . . . . . . . . . . . 123
Creating a table . . . . . . . . . . . . . . . . . . . . . . . 123
Destroying a table . . . . . . . . . . . . . . . . . . . . . . 123
Estimating table size . . . . . . . . . . . . . . . . . . . . . 123
Understanding materialized views . . . . . . . . . . . . . . . . . 124
Working with materialized views . . . . . . . . . . . . . . . . . 125
Creating a materialized view. . . . . . . . . . . . . . . . . . 125
The SELECT query in the CREATE MATERIALIZED VIEW statement
125
Restrictions on materialized views and detail tables. . . . . . . . . 126
Performance implications of materialized views . . . . . . . . . . 127
Destroying a materialized view. . . . . . . . . . . . . . . . . 129
Understanding views . . . . . . . . . . . . . . . . . . . . . . 130
Working with views . . . . . . . . . . . . . . . . . . . . . . 131
iv Oracle TimesTen In-Memory Database Operations Guide
Creating a view . . . . . . . . . . . . . . . .
The SELECT query in the CREATE VIEW statement .
Restrictions on views and their detail tables . . . . .
Destroying a view . . . . . . . . . . . . . . .
Understanding indexes . . . . . . . . . . . . . .
Working with indexes . . . . . . . . . . . . . . .
Creating an index . . . . . . . . . . . . . . .
Destroying an index . . . . . . . . . . . . . .
Estimating index size . . . . . . . . . . . . .
Understanding rows . . . . . . . . . . . . . . .
Working with rows . . . . . . . . . . . . . . . .
Inserting rows . . . . . . . . . . . . . . . .
Deleting rows . . . . . . . . . . . . . . . .
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Transaction semantics . . . . . . . . . . . . . . . . .
Transaction atomicity and durability . . . . . . . . . . .
Overview . . . . . . . . . . . . . . . . . . . .
Guaranteed atomicity and durability . . . . . . . . . .
Guaranteed atomicity, delayed durability . . . . . . . .
Guaranteed atomicity, no guaranteed durability . . . . .
No guaranteed atomicity, no guaranteed durability . . . .
Controlling durability and logging . . . . . . . . . . . .
Using durable commits . . . . . . . . . . . . . . .
Log files . . . . . . . . . . . . . . . . . . . .
Concurrency control . . . . . . . . . . . . . . . . .
Transaction isolation levels . . . . . . . . . . . . .
Locking granularities. . . . . . . . . . . . . . . .
Coexistence of different locking levels . . . . . . . . .
Checkpoints. . . . . . . . . . . . . . . . . . . . .
Types of checkpoints . . . . . . . . . . . . . . . .
Transaction-consistent checkpoints . . . . . . . .
Fuzzy or non-blocking checkpoints . . . . . . . .
Setting and managing checkpoints . . . . . . . . . .
Setting the checkpoint rate for background checkpoints
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7 Transaction Management and Recovery
8 Data Store Performance Tuning
System and data store tuning . . . . . . . . . .
Provide enough memory . . . . . . . . . .
Size your data store correctly . . . . . . . .
Use multi-processor optimizations if appropriate .
Increase LogBuffSize if needed . . . . . . .
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v
Use temporary data stores if appropriate . . . . . . . . . . . . . 161
Avoid connection overhead . . . . . . . . . . . . . . . . . . 161
Load the data store into RAM when duplicating . . . . . . . . . . 161
Avoid OS paging at load time . . . . . . . . . . . . . . . . . 162
Consider special options for maintenance. . . . . . . . . . . . . 162
Check your driver . . . . . . . . . . . . . . . . . . . . . . 162
Enable tracing only as needed . . . . . . . . . . . . . . . . . 162
Investigate alternative JVMs. . . . . . . . . . . . . . . . . . 163
Adjust log buffer size and CPU for a large number of subscribers . . . 163
Client/server tuning. . . . . . . . . . . . . . . . . . . . . . . 164
Work locally when possible . . . . . . . . . . . . . . . . . . 164
Use shared memory segment as IPC when client and server are on the same
machine . . . . . . . . . . . . . . . . . . . . . . . . . 164
Enable/Disable TT_PREFETCH_CLOSE for SELECT queries . . . . 165
Use a connection handle when calling SQLTransact . . . . . . . . 166
SQL tuning . . . . . . . . . . . . . . . . . . . . . . . . . . 168
Tune statements and use indexes . . . . . . . . . . . . . . . . 168
Select hash or T-tree indexes appropriately . . . . . . . . . . . . 169
Size hash indexes appropriately . . . . . . . . . . . . . . . . 170
Use foreign key constraint appropriately . . . . . . . . . . . . . 170
Computing exact or estimated statistics . . . . . . . . . . . . . 170
Avoid ALTER TABLE . . . . . . . . . . . . . . . . . . . . 171
Avoid nested queries . . . . . . . . . . . . . . . . . . . . . 171
Improving performance of materialized views . . . . . . . . . . . . 172
Limit number of join rows . . . . . . . . . . . . . . . . . . 172
Use indexes on join columns. . . . . . . . . . . . . . . . . . 172
Avoid unnecessary updates . . . . . . . . . . . . . . . . . . 172
Avoid changes to the inner table of an outer join . . . . . . . . . . 173
Limit number of columns in a view table . . . . . . . . . . . . . 173
Scaling to Multiple CPUs . . . . . . . . . . . . . . . . . . . . 174
Run the demo applications as a prototype. . . . . . . . . . . . . 174
Limit database-intensive connections per CPU . . . . . . . . . . 174
Use read operations when available . . . . . . . . . . . . . . . 175
Limit prepares, re-prepares and connects . . . . . . . . . . . . . 175
Limit replication transmitters and receivers and XLA readers . . . . . 175
Allow indexes to be rebuilt in parallel during recovery . . . . . . . 175
Use private commands . . . . . . . . . . . . . . . . . . . . 176
XLA acknowledgement modes . . . . . . . . . . . . . . . . . . 177
Prefetch multiple update records . . . . . . . . . . . . . . . . 177
Acknowledge XLA updates . . . . . . . . . . . . . . . . . . 177
vi
Oracle TimesTen In-Memory Database Operations Guide
9 The TimesTen Query Optimizer
When optimization occurs . . . . . . . .
Viewing a plan . . . . . . . . . . . .
Generating the plan . . . . . . . . .
Reading the PLAN table . . . . . . .
PLAN table columns . . . . . . . . .
Modifying plan generation . . . . . . . .
Why modify an execution plan? . . . .
When to modify an execution plan . . .
How to modify execution plan generation
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183
183
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185
187
187
187
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199
10 UNIX Configuration Files
Working with the ODBC.INI file . . .
The user ODBC.INI file . . . . .
The system ODBC.INI file . . . .
Searching for a DSN . . . . . . .
ODBC Data Sources . . . . . . .
Data Source Specification . . . . .
odbc.ini file example . . . . . . .
Working with the TTCONNECT.INI file
Defining a server name on UNIX . .
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Index
vii
viii Oracle TimesTen In-Memory Database Operations Guide
About this Guide
TimesTen® is a high-performance, in-memory data manager that supports the
ODBC and JDBC interfaces.
This guide provides:
• Background information to help you understand how TimesTen works.
• Step-by-step instruction and examples that show how to perform the most
commonly needed tasks.
To work with this guide, you should understand how database systems work and
have some knowledge of SQL (Structured Query Language).
1
TimesTen documentation
Including this guide, the TimesTen documentation set consists of these
documents:
• The Oracle TimesTen In-Memory Database Installation Guide provides
information needed to install and configure TimesTen on all supported
platforms.
• The Oracle TimesTen In-Memory Database Architectural Overview provides
a description of all the available features in TimesTen.
• The Oracle TimesTen In-Memory Database Operations Guide provides
information on configuring TimesTen and using the ttIsql utility to manage a
data store. This guide also provides a basic tutorial for TimesTen.
• The Oracle TimesTen In-Memory Database C Developer’s and Reference
Guide and the Oracle TimesTen In-Memory Database Java Developer’s and
Reference Guide provide information on how to use the full set of available
features in TimesTen to develop and implement applications that use
TimesTen.
• The Oracle TimesTen In-Memory Database Recommended Programming
Practices provides information that will assist developers who are writing
applications to work with TimesTen.
• The Oracle TimesTen In-Memory Database API and SQL Reference Guide
contains a complete reference to all TimesTen utilities, procedures, APIs and
other features of TimesTen.
• The Oracle TimesTen In-Memory Database TTClasses Guide describes how
to use the TTClasses C++ API to use the features available features in
TimesTen to develop and implement applications that use TimesTen.
• The TimesTen to TimesTen Replication Guide. This guide is for application
developers who use and administer TimesTen and for system administrators
who configure and manage TimesTen Replication. This guide provides background information to help you understand how TimesTen Replication works
and step-by-step instructions and examples that show how to perform the most
commonly needed tasks.
• The TimesTen Cache Connect to Oracle Guide describes how to use Cache
Connect to cache Oracle data in TimesTen. This guide is for developers who
use and administer TimesTen for caching Oracle data. It provides information
on caching Oracle data in TimesTen data stores. It also describes how to use
the Cache Administrator, a web-based interface for creating cache groups.
• The Oracle TimesTen In-Memory Database Troubleshooting Procedures
Guide provides information and solutions for handling problems that may
arise while developing applications that work with TimesTen, or while
configuring or managing TimesTen.
2 Oracle TimesTen In-Memory Database Operations Guide
TimesTen documentation is available on the product CD-ROM and on the Oracle
Technology Network: http://www.oracle.com/technology/documentation/
timesten_doc.html.
Background reading
For a conceptual overview and JDBC development information, see:
• Hamilton, Cattell, Fisher. JDBC Database Access with Java. Reading, MA:
Addison Wesley. 1998.
For a Java reference, see:
• Horstmann, Cornell. Core Java. Palo Alto, CA: Sun Microsystems Press.
1999.
• For the JDBC API specification, refer to java.sql package in the appropriate
Java Platform API Specification.
• If you are working with JDK 1.2, refer to the Java 2 Platform API
specification at: http://java.sun.com/products/jdk/1.2/docs/api/
index.html
• If you are working with JDK 1.3, refer to the Java 2 Platform API
specification at: http://java.sun.com/j2se/1.3/docs/api/index.html
• If you are working with JDK 1.4, refer to the Java 2 Platform API
specification at: http://java.sun.com/j2se/1.4/docs/api/index.html
• Siple, Matthew. The Complete Guide to Java Database Programming: JDBC,
ODBC and SQL. McGraw-Hill. 1997.
An extensive list of books about ODBC and SQL is in the Microsoft ODBC
manual included in your developer’s kit. In addition to this guide, your
developer’s kit includes the appropriate ODBC manual for your platform:
– Microsoft ODBC 3.0 Programmer’s Reference and SDK Guide provides
all relevant information on ODBC for Windows developers.
– Microsoft ODBC 2.0 Programmer’s Reference and SDK Guide, included
online in PDF format, provides information on ODBC for UNIX
developers.
For a conceptual overview and programming how-to of ODBC, see:
• Sanders, Roger E. ODBC 3.5 Developer's Guide (McGraw-Hill Series On
Data Warehousing and Data Management); McGraw-Hill. 1999
• Signore, Robert / Stegman, Michael O. / et al. ODBC Solution: Open
Database Connectivity in Distributed Environments: Mcgraw-hill Series On
Computer Communications; McGraw Hill. 1995
For a review of SQL, see:
• Melton, Jim and Simon, Alan R. Understanding the New SQL: A Complete
Guide. San Francisco, CA: Morgan Kaufmann Publishers. 1993.
About this Guide 3
• Groff, James R. / Weinberg, Paul N. SQL: The Complete Reference. McGrawHill. /1999
For information on Unicode, see:
• The Unicode Consortium, The Unicode Standard, Version 4.0,
Addison-Wesley, 2003.
• The Unicode Consortium Home Page at http://www.unicode.org
Installing TimesTen
TimesTen Release 6.0 includes the TimesTen Data Manager for 32-bit and 64-bit
platforms. See the Oracle TimesTen In-Memory Database Installation Guide for
a description of supported platforms.
In addition to the Data Manager, TimesTen Release 6.0 also includes TimesTen
Client and Server components. You can install the TimesTen Data Manager
stand-alone or in a client/server environment.
For a list of the The TimesTen default installation directories, see the Oracle
TimesTen In-Memory Database Installation Guide.
Conventions used in this guide
TimesTen supports multiple platforms. Unless otherwise indicated, the
information in this guide applies to all supported platforms. The term Windows
refers to Windows 2000, Windows XP and Windows Server 2003. The term
UNIX refers to Solaris, Linux, HP-UX, Tru64 and AIX.
TimesTen documentation uses these typographical conventions:
If you see...
It means...
code font
Code examples, filenames, and pathnames.
For example, the .odbc.ini.ttconnect.ini file.
italic code
font
A variable in a code example that you must replace.
For example:
Driver=install_dir/lib/libtten.sl
Replace install_dir with the path of your
TimesTen installation directory.
4 Oracle TimesTen In-Memory Database Operations Guide
TimesTen documentation uses these conventions in command line examples and
descriptions:
If you see...
It means...
fixed width
italics
Variable; must be replaced
[ ]
Square brackets indicate that an item in a command line
is optional.
{ }
Curly braces indicated that you must choose one of the
items separated by a vertical bar ( | ) in a command line.
|
A vertical bar (or pipe) separates arguments that you may
use more than one argument on a single command line.
...
An ellipsis (. . .) after an argument indicates that you may
use more than one argument on a single command line.
%
The percent sign indicates the UNIX shell prompt.
#
The number (or pound) sign indicates the UNIX root
prompt.
TimesTen documentation uses these variables to identify path, file and user
names:
If you see...
It means...
install_dir
The path that represents the directory where the current
release of TimesTen is installed.
TTinstance
The instance name for your specific installation of
TimesTen. Each installation of TimesTen must be
identified at install time with a unique alphanumeric
instance name. This name appears in the install path. The
instance name “giraffe” is used in examples in this guide.
bits or bb
Two digits, either 32 or 64, that represent either the 32-bit
or 64-bit operating system.
release or rr
Two digits that represent the first two digits of the current
TimesTen release number, with or without a dot. For
example, 50 or 5.0 represents TimesTen Release 5.0.
jdk_version
Two digits that represent the version number of the major
JDK release. For example 14 for versions of jdk1.4.
About this Guide 5
timesten
A sample name for the TimesTen instance administrator.
You can use any legal user name as the TimesTen
administrator. On Windows, the TimesTen instance
administrator must be a member of the Administrators
group. Each TimesTen instance can have a unique
instance administrator name.
DSN
The data source name.
6 Oracle TimesTen In-Memory Database Operations Guide
Finding the information you need
The table below provides a brief overview of the TimesTen development process.
It will help you get started with your application and find relevant information as
you progress.
To learn how to
See
Install TimesTen
Oracle TimesTen In-Memory Database
Installation Guide
Create and use a TimesTen data
store
Chapter 1, “QuickStart”
Use the ttIsql command-line
utility to execute SQL
Chapter 5, “Using the ttIsql Utility”
Manage TimesTen resources
Chapter 4, “Working with the Oracle
TimesTen Data Manager Daemon”
Configure TimesTen on UNIX
systems
Chapter 10, “UNIX Configuration Files”
Troubleshoot problems running
the TimesTen demos
The TimesTen Troubleshooting Procedures
Guide:
http://www.oracle.com/technology/
documentation/timesten_doc.html
Technical Support
For information about obtaining technical support for TimesTen products, go to
the following Web address:
http://www.oracle.com/support/contact.html
Email: timesten-support_us@oracle.com
About this Guide 7
8 Oracle TimesTen In-Memory Database Operations Guide
1
QuickStart
This tutorial provides a basic grounding in development using TimesTen. The
topics covered in this tutorial include:
• Overview
• Lesson 1: Defining a data source name (DSN)
• Lesson 2: Connecting to a data store
• Lesson 3: Creating tables
• Lesson 4: Populating the data store using ttBulkCp
• Lesson 5: Working with a data store
• Lesson 6: Data store backup
• Lesson 7: Destroying a data store
• Lesson 8: Restoring a data store
Overview
This tutorial walks you through the process of using the basic functions of
TimesTen. The tutorial will teach you how to:
• Define a Data Source Name (DSN).
• Connect to a data store.
• Execute SQL statements using the TimesTen ttIsql utility.
• Work with other TimesTen utilities.
In general, you can set your own pace for completing the tutorial. However,
TimesTen recommends completing an entire lesson in one sitting since each
lesson builds on a sequence of related tasks. After you have finished the tutorial,
you will have mastered the basics of using TimesTen.
Before you begin
Before starting the lesson plan in the basic tutorial, you need to complete the
installation of the software. Be sure that all software is installed according to the
instructions found in the Oracle TimesTen In-Memory Database Installation
Guide.
9
Lessons
You are going to build a database containing data regarding information on a
fictitious group of customers who purchase dictionaries. You will define a DSN,
create a data store, build tables and populate the tables with data supplied within
the demo directory. You will then work with the data store using various
TimesTen utilities.
Lesson 1: Defining a data source name (DSN)
Data sources and data stores
A data store is a collection of TimesTen tables and indexes. The name of a data
store is identified by the path name of its checkpoint and log files, which you
enter when creating a DSN.
A data source is an ODBC entity that defines configuration information used to
connect to a data store. The connection’s configuration is determined by the
settings of the data source’s attributes.
A DSN is a logical name for a data source. The ODBC driver uses a DSN to
connect to a data store. DSNs are case insensitive. The DSN uses the data store
path name to map to the data store. More than one DSN can be mapped to the
same data store to create different connection configurations to that data store.
Defining a DSN on Windows
Use the ODBC TimesTen Setup dialog to define a DSN:
1.
From the desktop, choose Start > Control Panel > Administrative Tools >
Data Sources (ODBC).
2.
Double click Data Sources (ODBC).
3.
Click the User DSN or System DSN tab.
4.
Click Add. The Create New Data Source dialog appears.
5.
Choose Oracle TimesTen Data Manager 6.0.
6.
Click Finish. The ODBC TimesTen Setup dialog appears.
7.
Click Data Store.
8.
In the Data Source Name field, type: ref_customers.
Note: The Data Source Name and the data store name do not need to be the
same. They are presented here as such for simplicity.
10 Oracle TimesTen In-Memory Database Operations Guide
9.
In the Data Store Path and Name field, type c:\temp\ref_customers.
10. Click the First Connection tab.
11. In the Permanent Data Size field, type 20. Size specifies the initial size, in
megabytes, of the data store.
12. In the Log Files Size (MB) field, type 8.
Note: Be sure AutoCreate is checked. Lesson 2 uses this attribute. On
connection the data store will be created if it does not exist.
13. Click General Connection.
QuickStart 11
14. Make sure that DurableCommits is unchecked. This minimizes writing to the
log buffer and improves performance.
15. Click OK.
16. Click OK on the ODBC Data Source Administrator.
For details on the TimesTen attributes, refer to Chapter 1, “Data Store Attributes
in the Oracle TimesTen In-Memory Database API and SQL Reference Guide.
Defining a DSN on UNIX
On UNIX, you must create a configuration file in your home directory prior to
running TimesTen. For details on the UNIX configuration files, see Chapter 10,
“UNIX Configuration Files.” A sample file containing definitions for the DSNs
required by TimesTen is provided in:
/var/timesten/TTinstance/sys.odbc.ini.
If you have an.odbc.ini file in your home directory, merge the contents of the
sys.odbc.ini file into your .odbc.ini file. If a DSN is defined in both your
user .odbc.ini file and the system .odbc.ini file, TimesTen uses the definition
in your user .odbc.ini file.
After the .odbc.ini file has been created in your home directory, create the
entry:
[ODBC Data Sources]
ref_customers=TimesTen 6.0 Driver
[ref_customers]
DataStore=/tmp/ref_customers
DurableCommits=0
PermSize=16
12 Oracle TimesTen In-Memory Database Operations Guide
LogFileSize=8
Now that you have defined a DSN, the next step is to connect to the data store.
For further information on creating a data store, refer to the Oracle TimesTen InMemory Database API and SQL Reference Guide.
Lesson 2: Connecting to a data store
When the DSN was defined in Lesson 1, the AutoCreate attribute was set to
allow for creation of the data store at connection. You are now ready to connect
to the data store. You will be using the TimesTen utility ttIsql. The ttIsql utility
allows you to run SQL interactively from the command line.
Using ttIsql on Windows
Perform the following steps to connect to the data store:
1.
Choose Start > Run.
2.
Type cmd in the Run field. The Command Prompt dialog appears.
3.
At the prompt, type ttIsql. This command returns the message:
ttIsql (c) 1996-2005, Oracle. All rights reserved. Type ? or help,
type “exit” to quit ttIsql. All commands must end with a semicolon
character.
Command>
4.
At the ttIsql command prompt, type
connect “DSN=ref_customers”;
5.
Press Enter. The message (Default setting AutoCommit=1) returns.
Note: If ttIsql is not a recognized command in the Command Prompt window,
run the install_dir\bin\ttVars.bat file to add it to your System Path.
Using ttIsql on UNIX
Perform the following steps to connect to a data store using UNIX:
1.
Type ttIsql at the command prompt.
2.
The following message is returned:
ttIsql (c) 1996-2005, Oracle. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.
All commands must end with a semi-colon character.
3.
At the ttIsql prompt, type:
connect “DSN=ref_customers”;
4.
Press Enter. The following message is returned:
QuickStart 13
(Default setting AutoCommit=1)
Now that the connection has been made the next step is to create the tables that
you are going to populate. To obtain help with ttIsql, type ?, or help. For further
information on ttIsql, refer to the Oracle TimesTen In-Memory Database API
and SQL Reference Guide.
Lesson 3: Creating tables
Creating tables in TimesTen requires some prior knowledge of SQL and
planning. While this tutorial walks you through creating the tables in this lesson,
it is not a substitute for understanding database design principles.
You will build three tables: the first contains customer information, the second
contains reference product information, and the third tracks customer orders.
Later you will populate the tables with data from the install_dir/demo
directory.
First you need a table called customer with the following columns:
Column
Name
Data type
Nullable?
Key
cust_number
Integer
not null
primary key
first_name
Char (12)
not null
last_name
Char (12)
not null
address
Varchar (100)
not null
To create the customer information table, execute the following SQL statement at
the ttIsql prompt:
CREATE TABLE customer
(cust_number integer not null primary key,
first_name char (12) not null,
last_name char (12) not null,
address varchar (100) not null);
To view what you have just created, execute the describe command that is a part
of ttIsql. The describe command returns the structure of each table, including
the table name, the column names and data types.
To view the column definitions for the table you created, execute the following
ttIsql statement:
describe customer;
The describe command returns the following definitions:
14 Oracle TimesTen In-Memory Database Operations Guide
Table owner.CUSTOMER
Columns:
*CUST_NUMBER
INTEGER NOT NULL
FIRST_NAME
CHAR(12) NOT NULL
LAST_NAME
CHAR(12) NOT NULL
ADDRESS
VARCHAR(100) NOT NULL
1 table found
(primary key columns are indicated with *)
After you have built the Customer table, create the two other tables needed to
perform queries in later lessons. Use the same syntax as above to create the
columns of the new tables.
Create the following table called ref_products:
Column
Data type
Null?
Keys
prod_number
char (10)
not null
primary key
prod_name
varchar (100)
not null
price
decimal (6,2)
Create the following table called Orders:
Column
Data type
Null?
order_number
integer
not null
cust_number
integer
not null
prod_number
char (10)
not null
order_date
date
not null
Keys
To be sure the columns you have created are correct, execute the describe
command as you did above. The describe command should return the following
definition for the ref_products table:
Table owner.REF_PRODUCTS
Columns:
*PROD_NUMBER
CHAR(10) NOT NULL
PROD_NAME
VARCHAR(100) NOT NULL
PRICE
DECIMAL(6,2) NOT NULL
1 table found
and the following definition for the Orders table:
Table owner.ORDERS
Columns:
QuickStart 15
ORDER_NUMBER
CUST_NUMBER
PROD_NUMBER
ORDER_DATE
1 table found
INTEGER NOT NULL
INTEGER NOT NULL
CHAR(10) NOT NULL
DATE NOT NULL
To see the full scheme of this data store, use the ttSchema utility from a ttIsql
session. Enter the following at thettIsql prompt:
host ttSchema ref_customers
Type exit at the ttIsql prompt. TimesTen “checkpoints” the data store, saving
the information to disk, making it ready for the next connection.
Now that you have created the tables, you are ready to populate them with data.
There are data files located in the install_dir/demo which you will use for
population. The next lesson will walk you through populating the tables with a
TimesTen utility.
Lesson 4: Populating the data store using ttBulkCp
The ttBulkCp utility copies data between TimesTen tables and ASCII files. Files
containing data to populate the tables you created in Lesson 3 are located in the
demo directory. The titles are customer.dat, orders.dat and
ref_products.dat. For easy identification, the data files have the same base
name as the table names.
To populate the Customer table, perform the following steps:
Execute the following statement at the command prompt:
ttBulkCp -i -d warn DSN=ref_customers owner.customer customer.dat
Note: You must specify the path or directory of the .dat file. If the full path of
the file contains spaces the path and file name must be contained in double
quotes. The owner name is given when a describe command is executed from
ttIsql as in Lesson 3. For a full explanation of the arguments given, refer to the
Oracle TimesTen In-Memory Database API and SQL Reference Guide.
The following message appears:
customer.dat:
25 rows inserted
25 rows total
To view the data loaded into the Customer table, perform the following steps:
1.
Connect to the DSN with ttIsql as described in Lesson 2.
2.
Execute the following SQL statement at the ttIsql prompt:
16 Oracle TimesTen In-Memory Database Operations Guide
SELECT * FROM customer;
The results of the SELECT are as follows:
< 3700,
< 1121,
< 1278,
< 1868,
< 3645,
< 1935,
< 1002,
< 2364,
< 2655,
< 1077,
< 3864,
< 1010,
< 2300,
< 1001,
< 3525,
< 2826,
< 2435,
< 1224,
< 3611,
< 1900,
< 3290,
< 1665,
< 3098,
< 1133,
< 2555,
25 rows
Peter
Saul
Mary
Paul
John
Sandra
Marco
Karen
Linda
Gautam
Ruth
Fatima
Pavel
Steven
Anthony
Mary
Juanita
Abdul
Katherine
Patricia
Paula
David
Cynthia
Kerri
Bo
found.
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
Burchard
Mendoza
Behr
Tu
Silva
Lao
Mueller
Johnson
Garcia
Mudunuri
Silver
Borba
Popov
McPhee
Bianchi
Anderson
Dawes
Aziz
McKenzie
Levesque
Rossi
Singh
Stewart
Haas
Smith
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
882 Osborne Avenue, Boston, MA 02122 >
721 Stardust Street, Mountain View, CA 94043 >
2233 Emerson Road, Vancouver, WA 98663 >
308 Bowman Court, Palo Alto, CA 94309 >
3329 Taffy Lane, Atlanta, GA 30314 >
115 Spangler Avenue, San Jose, CA 95112 >
40 East 5th Avenue, New York, NY 10009 >
3971 Hill Road, Chicago, IL 60608 >
7599 Clark Road, Denver, CO 80210 >
16 Welsley Avenue, Fremont, CA 94555 >
88 West 65th Street, New York, NY 10009 >
6868 Bascom Avenue, San Jose, CA 95128 >
233 Loredo Street, Dallas, TX 75210 >
72 Vine Street, San Jose, CA 95125 >
122 Fuller Avenue, Patchogue, NY 11772 >
6363 Bjorn Road, Minneapolis, MN 55417 >
733 Valdosta Avenue, Baton Rouge, LA 70816 >
6793 Bird Avenue, San Jose, CA 95126 >
54 East 21st Avenue, New York, NY 10009 >
658 Aristotle Road, Palo Alto, CA 94305 >
21 West 54th Street, New York, NY 10009 >
4001 West Hedding, San Jose, CA 95216 >
333 East Palm Street, Miami, FL 33150 >
68 East San Fernando, San Jose, CA 95113 >
124 North 1st Street, Dallas, TX 75210 >
With the same syntax as above, use the ttBulkCp utility to populate the
ref_products and Orders tables with the corresponding .dat files located in the
demo directory.
Execute a SELECT statement as above. The results of the SELECT for the
Orders table are as follows:
Command> select * from orders;
< 6853036, 3700, 0028616731, 1996-04-05
< 6853041, 3700, 0198612710, 1997-01-12
< 6853169, 1121, 0003750299, 1997-08-01
< 6853174, 1121, 0789428741, 1998-02-02
< 6853179, 1121, 0198612583, 1998-10-25
< 6853302, 1278, 0198612605, 1998-08-22
< 6853435, 1868, 0198613202, 1999-04-15
< 6853568, 3645, 0028616731, 1998-06-28
< 6853701, 1935, 0395671612, 1998-02-12
< 6853834, 1002, 0395448956, 1998-05-07
< 6853967, 2364, 0877797099, 1997-08-30
< 6853967, 2364, 0789435578, 1997-08-30
>
>
>
>
>
>
>
>
>
>
>
>
QuickStart 17
< 6853967, 2364,
< 6854100, 2655,
< 6854105, 2655,
< 6854233, 1077,
< 6854366, 3864,
< 6854499, 1010,
< 6854632, 2300,
< 6854765, 1001,
< 6854765, 1001,
< 6854765, 1001,
< 6854770, 1001,
< 6854898, 3525,
< 6855031, 2826,
< 6855036, 2826,
< 6855164, 2435,
< 6855297, 1224,
< 6855297, 1224,
< 6855297, 1224,
< 6855297, 1224,
< 6855430, 3611,
< 6855435, 3611,
< 6855440, 3611,
< 6855445, 3611,
< 6855563, 1900,
< 6855696, 3290,
< 6855701, 3290,
< 6855829, 1665,
< 6855962, 3098,
< 6855967, 3098,
< 6856095, 1133,
< 6856228, 2555,
43 rows found.
0877799113,
0440218616,
0877797099,
0789435578,
0877799113,
0028616731,
0877799113,
0198612605,
0789435578,
0877799113,
0198612710,
0877799113,
0028616731,
0877799113,
0385312547,
0877799113,
0877797099,
0789435578,
0198612605,
0877797099,
0877799113,
0198612710,
0198612583,
0194314219,
0385312547,
0028616731,
0440218616,
0877799113,
0789435578,
0877799113,
0194314219,
1997-08-30
1996-07-22
1997-08-30
1997-12-01
1998-09-20
1998-06-06
1999-10-15
1999-11-25
1999-11-25
1999-11-25
1999-12-07
1998-08-08
1996-03-01
1996-03-08
1997-02-05
1996-01-03
1996-01-03
1996-01-03
1996-01-03
1997-06-24
1997-12-05
1998-03-13
1998-11-11
1998-05-07
1998-08-22
1999-03-01
1998-08-30
1997-04-07
1998-04-14
1996-05-02
1999-06-17
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
>
Execute a SELECT statement as above for the third table. The results of the
SELECT for the ref_products table are as follows:
Command> select * from ref_products;
< 0194314219, Oxford Advanced Learner's Dictionary of Current English, 26.95 >
< 0877799113, The Merriam Webster Dictionary, 5.99 >
< 0789435578, Dk Illustrated Oxford Dictionary, 50.00 >
< 0877797099, Merriam Webster's Collegiate Dictionary (10th Edition), 24.95 >
< 0395671612, The American Heritage College Dictionary, 24.00 >
< 0198613202, The Concise Oxford Dictionary of Current English, 29.95 >
< 0385312547, The American Heritage Dictionary, 12.95 >
< 0003750299, Collins Cobuild English Dictionary, 55.00 >
< 0395448956, The American Heritage Dictionary of the English Language, 50.00 >
< 0198612710, The New Shorter Oxford English Dictionary (2 Vol.), 135.00 >
< 0198612583, The Compact Oxford English Dictionary, 375.00 >
< 0198612605, Oxford English Dictionary: CD-Rom for Windows (20 Vol./1 CD), 395.
18 Oracle TimesTen In-Memory Database Operations Guide
00 >
< 0789428741, Ultimate Visual Dictionary, 16.95 >
< 0028616731, Webster's New World College Dictionary, 23.95 >
< 0440218616, The American Heritage Dictionary (Paperback), 6.50 >
15 rows found.
After the tables have been populated, you can work with the data store as you
would with any other database. In the next lesson you will work with the data
store with various utilities. For further information on the ttBulkCp utility, refer
to the Oracle TimesTen In-Memory Database API and SQL Reference Guide.
Lesson 5: Working with a data store
Lesson 5A: Inserts
You are now ready to work with the data store you created. Just as with any
database, you can execute SQL statements to insert rows into tables. For
example, suppose new customers need to be added to the data store. The first
new customer to be added is Josephine Rogers. You use INSERT statements and
VALUES clauses to add her information to the customer table.
The INSERT statement allows you to add rows to the data store. Along with the
INSERT statement, use a VALUES clause to populate the columns with the
desired information.
To insert a row containing new customer information into your data store,
execute the following SQL statement at the ttIsql prompt:
INSERT INTO customer
VALUES (1365,’Josephine’,’Rogers’,’2100 Augustine Drive, Santa
Clara, CA 95054’);
You must type the data values in the same order as the column names in the
original CREATE TABLE statement in Lesson 3 (the customer number first, first
name second, etc.). The string values must use single quotes.
To view the new row inserted into the Customer table, execute the following
SQL statement:
QuickStart 19
SELECT * FROM customer WHERE cust_number=1365;
Use a separate INSERT statement for each row when you add the following
customers:
cust_
number
first_
name
last_
name
address
3750
Michelle
Ioni
12 Kipling Street, Denver, CO
80215
3836
Dante
Cremona
202 Tampa Way, Fremont, CA
94539
3945
Mark
Edwards
1 Market Street, San Francisco,
CA 94126
To view the rows inserted in the data store, execute the following SELECT
statement:
SELECT * FROM customer WHERE cust_number>=3750;
The SELECT statement returns the following results:
<
<
<
<
3864,
3750,
3836,
3945,
Ruth,
Michelle,
Dante,
Mark,
Silver,
Ioni,
Cremona,
Edwards,
88 West 65th Street,
12 Kipling Street,
202 Tampa Way,
1 Market Street,
New York,
Denver,
Fremont,
San Francisco,
NY
CO
CA
CA
10009
80215
94539
94126
>
>
>
>
Lesson 5B: Selects
When you populated the tables in Lesson 4, you noticed that for the orders table
some of the customer numbers and order numbers were repeated. You can create
a SELECT statement to give a sum total of the repeated order numbers. To make
the report readable, you can use clauses to sort the results.
The aggregate syntax SUM, which gives the total of the values in the numeric
expression, is used to add the amount of those repeated order numbers. The
WHERE clause uses JOINS to link information from the three tables. And, as
much as WHERE qualifies individual rows, the GROUP BY clause groups
common rows together. Further, the ORDER BY clause makes the results more
readable. It allows you to sort by any set of columns in the SELECT list. In this
example, 4 is order date, 1 is last name, and 2 is first name.
20 Oracle TimesTen In-Memory Database Operations Guide
To find the total of the customers’ orders by date, execute the following SELECT
statement:
SELECT last_name, first_name, SUM (price),order_date
FROM customer c, ref_products r, orders o
WHERE c.cust_number=o.cust_number and r.prod_number=o.prod_number
GROUP BY last_name, first_name, order_date
ORDER BY 4,1,2;
The results of the query are as follows:
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
Aziz
Anderson
Anderson
Burchard
Haas
Garcia
Burchard
Dawes
Stewart
McKenzie
Mendoza
Garcia
Johnson
Mudunuri
McKenzie
Mendoza
Lao
McKenzie
Stewart
Levesque
Mueller
Borba
Silva
Bianchi
Behr
Rossi
Singh
Silver
Mendoza
McKenzie
Rossi
Tu
Smith
Popov
McPhee
McPhee
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
,
Abdul
, 475.94, 1996-01-03 >
Mary
, 23.95, 1996-03-01 >
Mary
, 5.99,
1996-03-08 >
Peter
, 23.95, 1996-04-05 >
Kerri
, 5.99,
1996-05-02 >
Linda
, 6.50,
1996-07-22 >
Peter
, 135.00, 1997-01-12 >
Juanita
, 12.95, 1997-02-05 >
Cynthia
, 5.99,
1997-04-07 >
Katherine , 24.95, 1997-06-24 >
Saul
, 55.00, 1997-08-01 >
Linda
, 24.95, 1997-08-30 >
Karen
, 80.94, 1997-08-30 >
Gautam
, 50.00, 1997-12-01 >
Katherine , 5.99,
1997-12-05 >
Saul
, 16.95, 1998-02-02 >
Sandra
, 24.00, 1998-02-12 >
Katherine , 135.00, 1998-03-13 >
Cynthia
, 50.00, 1998-04-14 >
Patricia , 26.95, 1998-05-07 >
Marco
, 50.00, 1998-05-07 >
Fatima
, 23.95, 1998-06-06 >
John
, 23.95, 1998-06-28 >
Anthony
, 5.99,
1998-08-08 >
Mary
, 395.00, 1998-08-22 >
Paula
, 12.95, 1998-08-22 >
David
, 6.50,
1998-08-30 >
Ruth
, 5.99,
1998-09-20 >
Saul
, 375.00, 1998-10-25 >
Katherine , 375.00, 1998-11-11 >
Paula
, 23.95, 1999-03-01 >
Paul
, 29.95, 1999-04-15 >
Bo
, 26.95, 1999-06-17 >
Pavel
, 5.99,
1999-10-15 >
Steven
, 450.99, 1999-11-25 >
Steven
, 135.00, 1999-12-07 >
QuickStart 21
Lesson 5C: Updates
While INSERT adds new rows to a table, UPDATE changes existing rows. Use
UPDATE to change values in single rows, groups of rows, or all the rows in a
table.
The UPDATE specifies the row or rows you want to change. For example, we
want to discount those reference products costing $50.00 or more by 10%. To
begin, perform a SELECT to view the products costing $50.00 or more.
At the command prompt, type the following:
SELECT * FROM ref_products
WHERE price >= 50.00;
The following list returns:
<
<
<
<
<
<
0789435578,
0003750299,
0395448956,
0198612710,
0198612583,
0198612605,
Dk Illustrated Oxford Dictionary,
50.00
Collins Cobuild English Dictionary,
55.00
The American Heritage Dictionary of the English Language, 50.00
The New Shorter Oxford English Dictionary (2 Vol.),
135.00
The Compact Oxford English Dictionary,
375.00
Oxford English Dictionary: CD-Rom for Windows(20Vol./1CD),395.00
>
>
>
>
>
>
The UPDATE is followed by a SET clause which specifies the column and
changed values. To discount the price of the six products above by 10%, multiply
the price by a value of.90.
At the command prompt, type the following:
UPDATE ref_products
SET price = price * .90
WHERE price >= 50.00;
The following message returns:
6 rows updated
To view the new prices, execute the following at the command prompt:
SELECT * FROM ref_products
WHERE price >= 45.00;
The following list returns:
< 0789435578,
< 0003750299,
< 0395448956,
< 0198612710,
< 0198612583,
< 0198612605,
50 >
Dk Illustrated Oxford Dictionary, 45.00 >
Collins Cobuild English Dictionary, 49.50 >
The American Heritage Dictionary of the English Language, 45.00 >
The New Shorter Oxford English Dictionary (2 Vol.), 121.50 >
The Compact Oxford English Dictionary, 337.50 >
Oxford English Dictionary: CD-Rom for Windows (20 Vol./1 CD), 355.
22 Oracle TimesTen In-Memory Database Operations Guide
Lesson 5D: Deletes
It is just as important to be able to remove rows as it is to be able to add or change
them. Like INSERT and UPDATE, CREATE VIEW works for single operations
as well as multiple-row operations.
For example, suppose our customer Steven McPhee has contacted us and wants
to cancel an order placed in November 1999. Mr. McPhee’s customer number is
1001.
To view all of Steven Mcphee’s orders, type the following at the command
prompt:
SELECT * FROM orders
WHERE cust_number = 1001;
The following list returns:
<
<
<
<
6854765,
6854765,
6854765,
6854770,
1001,
1001,
1001,
1001,
0198612605,
0789435578,
0877799113,
0198612710,
1999-11-25
1999-11-25
1999-11-25
1999-12-07
>
>
>
>
There are two orders for Mr. McPhee. Since order number 6854765 is the order
placed in November 1999, this is the one which will be deleted from the orders
table.
To delete order number 6854765, type the following at the command prompt:
DELETE from orders
WHERE order_number = 6854765;
The following message returns:
(3 rows affected)
To view Steven McPhee’s current orders, type the following at the command
prompt:
SELECT * FROM orders
WHERE cust_number = 1001;
The following order returns:
< 6854770, 1001, 0198612710, 1999-12-07 >
The SELECT statement shows that Steven McPhee now has only one order on
record.
Now that an individual order has been deleted, you are ready to update the data
store, and delete those records which were placed prior to 1997. First you need to
find those orders from the following SELECT statement:
QuickStart 23
SELECT * FROM orders
WHERE order_date <= '1996-12-31';
The following orders return:
<
<
<
<
<
<
<
<
<
6853036,
6854100,
6855031,
6855036,
6855297,
6855297,
6855297,
6855297,
6856095,
3700,
2655,
2826,
2826,
1224,
1224,
1224,
1224,
1133,
0028616731,
0440218616,
0028616731,
0877799113,
0877799113,
0877797099,
0789435578,
0198612605,
0877799113,
1996-04-05
1996-07-22
1996-03-01
1996-03-08
1996-01-03
1996-01-03
1996-01-03
1996-01-03
1996-05-02
>
>
>
>
>
>
>
>
>
As you can see, there are nine orders placed prior to 1997. These are the orders
which you need to delete.
The CREATE VIEW statement uses the same WHERE clause you used in the
query above. To delete those orders placed before January 1, 1997, execute the
following at the command prompt:
DELETE FROM orders
WHERE order_date <= '1996-12-31';
The following message returns:
9 rows deleted
The nine orders have been deleted from the data store.
Now that the data store has been updated, you can perform a backup. The backup
takes a snapshot of the data store for a possible restore. For further information
on working with a data store, please refer to the Oracle TimesTen In-Memory
Database API and SQL Reference Guide, and the TimesTen C or Java
Developer's Guide.
Lesson 6: Data store backup
To take a snapshot of a data store in order to later use that data store in the exact
same state, use the ttBackup utility (the ttRestore utility is used for restoring the
data store and is covered in Lesson 8).
To backup the data store, perform the following:
1.
Type exit at the ttIsql prompt.
2.
Execute the following statement at the prompt:
Unix:
ttBackup -dir /tmp "DSN=ref_customers"
Windows: ttBackup -dir \temp "DSN=ref_customers"
24 Oracle TimesTen In-Memory Database Operations Guide
The following message appears:
Backup started
Backup complete
This message informs you that the backup is complete and was successful.
For further information on using the ttBackup utility, refer to the Oracle
TimesTen In-Memory Database API and SQL Reference Guide.
You have now completed a backup and are ready to destroy a data store in the
next lesson.
Lesson 7: Destroying a data store
If a data store becomes corrupted, or needs to be deleted, it can be destroyed. The
ttDestroy utility destroys a data store including all checkpoint files, transaction
logs and daemon catalog entries (though not the DSNs).
Before using the ttDestroy utility check the name of all data stores within
TimesTen. Use the ttStatus utility to display this information. The ttStatus
utility displays information that describes the current state of TimesTen. This
information includes the state of the TimesTen daemon process and all
subdaemon processes; the names of all existing TimesTen data stores; the
number of users currently connected to each TimesTen data store; and various
other information.
Using ttStatus
Execute the following at the command prompt:
ttStatus
The following statement returns:
TimesTen status report as of Thu Apr 22 12:44:03 2005
Daemon pid 2200 port 15100 instance tt51
TimesTen server pid 4092 started on port 15102
-----------------------------------------------Data store c:\temp\ref_customers
There are no connections to the data store
Replication policy : Manual
Oracle agent policy : Manual
-----------------------------------------------End of report
You will use this utility to verify that the data store has been destroyed.
QuickStart 25
Using ttDestroy
To destroy the data store, execute the following at the command prompt:
UNIX: ttDestroy /tmp/ref_customers
Windows: ttDestroy \temp\ref_customers
Execute the ttStatus utility again.
The following statement returns:
TimesTen status report as of Thu Apr 22 12:48:03 2005
Daemon pid 2200 port 15100 instance tt51
TimesTen server pid 4092 started on port 15102
------------------------------------------------End of report
Once the data store has been destroyed, you can restore it from the backup which
was made in Lesson 6. For further information on the ttDestroy utility, refer to
the TimesTen C Developer's Guide or the TimesTen Java Developer's Guide.
Lesson 8: Restoring a data store
To restore your data store, you will use the ttRestore utility. The ttRestore utility
restores a data store that has been backed up using the ttBackup utility. If the
data store has not been destroyed, ttRestore will not overwrite any current data
store.
To restore the ref_customers data store, execute the following at the command
prompt:
UNIX: ttRestore -dir /tmp "DSN=ref_customers"
Windows: ttRestore -dir C:\temp "DSN=ref_customers"
Note: The required information when using ttRestore is the directory where the
backup files are stored and the ODBC connection string for the data store. Refer
to “Lesson 6: Data store backup” on page 24 for the directory where the files are
stored.
The following message appears:
Restore started...
When the restore is complete, the following message appears:
Restore complete
Perform the following steps to verify the restore:
1.
At the command prompt, type ttIsql.
2.
At the ttIsql command prompt, connect to the data store by typing:
26 Oracle TimesTen In-Memory Database Operations Guide
connect "DSN=ref_customers";
3.
Execute the following SQL statement at the ttIsql prompt:
SELECT * FROM customer;
The results of the SELECT are as follows:
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
<
3700,
1121,
1278,
1868,
3645,
1935,
1002,
2364,
2655,
1077,
3864,
1010,
2300,
1001,
3525,
2826,
2435,
1224,
3611,
1900,
3290,
1665,
3098,
1133,
2555,
1365,
3750,
3836,
3945,
Peter,
Saul,
Mary,
Paul,
John,
Sandra,
Marco,
Karen,
Linda,
Gautam,
Ruth,
Fatima,
Pavel,
Steven,
Anthony,
Mary,
Juanita,
Abdul,
Katherine,
Patricia,
Paula,
David,
Cynthia,
Kerri,
Bo,
Josephine,
Michelle,
Dante,
Mark,
Burchard,
Mendoza,
Behr,
Tu,
Silva,
Lao,
Mueller,
Johnson,
Garcia,
Mudunuri,
Silver,
Borba,
Popov,
McPhee,
Bianchi,
Anderson,
Dawes,
Aziz,
McKenzie,
Levesque,
Rossi,
Singh,
Stewart,
Haas,
Smith,
Rogers,
Ioni,
Cremona,
Edwards,
882 Osborne Avenue, Boston, MA 02122 >
721 Stardust Street, Mountain View, CA 94043 >
2233 Emerson Road, Vancouver, WA 98663 >
308 Bowman Court, Palo Alto, CA 94309 >
3329 Taffy Lane, Atlanta, GA 30314 >
115 Spangler Avenue, San Jose, CA 95112 >
40 East 5th Avenue, New York, NY 10009 >
3971 Hill Road, Chicago, IL 60608 >
7599 Clark Road, Denver, CO 80210 >
16 Welsley Avenue, Fremont, CA 94555 >
88 West 65th Street, New York, NY 10009 >
6868 Bascom Avenue, San Jose, CA 95128 >
233 Loredo Street, Dallas, TX 75210 >
72 Vine Street, San Jose, CA 95125 >
122 Fuller Avenue, Patchogue, NY 11772 >
6363 Bjorn Road, Minneapolis, MN 55417 >
733 Valdosta Avenue, Baton Rouge, LA 70816 >
6793 Bird Avenue, San Jose, CA 95126 >
54 East 21st Avenue, New York, NY 10009 >
658 Aristotle Road, Palo Alto, CA 94305 >
21 West 54th Street, New York, NY 10009 >
4001 West Hedding, San Jose, CA 95216 >
333 East Palm Street, Miami, FL 33150 >
68 East San Fernando, San Jose, CA 95113 >
124 North 1st Street, Dallas, TX 75210 >
2100 Augustine Drive, Santa Clara, CA 95054 >
12 Kipling Street, Denver, CO 80215 >
202 Tampa Way, Fremont, CA 94539 >
1 Market Street, San Francisco, CA 94126 >
You have now completed the QuickStart tutorial and are ready to move on to
planning and implementing your own data store. Your TimesTen documentation
set is a complete reference to utilities and SQL.
Other considerations
If you are about to put a real-world data store online, you have several critical
issues, like indexing and integrity to consider. TimesTen assumes you will
consider these issues as you develop your design, and after completing the
tutorial. Contact TimesTen Customer Support if you have any further questions.
QuickStart 27
28 Oracle TimesTen In-Memory Database Operations Guide
2
Creating TimesTen Data Stores
A TimesTen data store is a collection of tables and indexes that can be accessed
and manipulated through SQL. This chapter describes how to set up a TimesTen
data store. It begins with an overview of the things you should consider when
setting up a data store and then describes each task in detail.
Once you have created a data store, you can:
• Use the ttIsql utility to connect to the data store and execute a SQL file or
start an interactive SQL session, as described in “Batch mode vs. interactive
mode” on page 90.
• Execute an application that uses the data store, as described Oracle TimesTen
In-Memory Database Java Developer’s and Reference Guide and Oracle
TimesTen In-Memory Database C Developer’s and Reference Guide.
The main topics are:
• TimesTen ODBC and JDBC drivers
• Data source names
• Creating a DSN on Windows
• Creating a DSN on UNIX
• DSN examples
• Specifying the size of a data store
• Specifying a RAM policy
• Configuring a diskless data store
• Copying, migrating, backing up and restoring a data store
29
TimesTen ODBC and JDBC drivers
This section describes some basic concepts that will help you define TimesTen
data stores. The main topics are:
• TimesTen ODBC drivers
• TimesTen JDBC driver
C applications interact with TimesTen either by linking directly with a TimesTen
ODBC driver, or by linking with an ODBC driver manager. Java applications
access the ODBC driver through a JDBC library. Consider the following points:
• An application that uses an ODBC driver manager dynamically loads an
ODBC driver at runtime. A single application can use more than one ODBC
driver within the same application, even if the drivers are for different
RDBMS products. The downside to this flexibility is that the driver manager
adds additional runtime overhead.
• An application that links directly with an ODBC driver can use only the driver
with which it is linked. This option offers less flexibility but better
performance than linking with a driver manager.
• An application that is using an ODBC driver manager cannot use XLA.
On Windows, TimesTen installs the ODBC driver manager if it is not already
present on the machine.
On UNIX, ODBC driver managers are available from third-party vendors.
ODBC driver managers are not supplied with UNIX systems. This guide refers to
the use of a driver manager for Windows systems only.
For more information on how to compile an application that uses the TimesTen
data manager, see Oracle TimesTen In-Memory Database Java Developer’s and
Reference Guide and Oracle TimesTen In-Memory Database C Developer’s and
Reference Guide.
TimesTen ODBC drivers
TimesTen includes two versions of the Data Manager ODBC driver: a production
version and a debug version.
• Use the production version of the TimesTen Data Manager driver for most
application development and for all deployment.
• Use the debug version of the TimesTen Data Manager driver only if you
encounter problems with TimesTen itself. This version performs additional
internal error checking and is slower than the production version. (On UNIX,
the TimesTen debug libraries are compiled with the -g option to display
additional debug information.)
TimesTen also includes the TimesTen Client ODBC driver for use with client/
server applications.
30 Oracle TimesTen In-Memory Database Operations Guide
On Windows, the production version of the TimesTen Data Manager is installed
by default. To install the debug version, choose Custom setup. To install the
TimesTen Client driver, choose either Typical or Custom setup. The following
table lists the ODBC drivers for Windows:
Platform
Version
Name
Windows
Production
TimesTen Data Manager 6.0 Driver.
Windows
Debug
TimesTen Data Manager 6.0 Debug Driver.
Windows
Client
TimesTen Client 6.0 Driver
On UNIX, depending on the options selected at install time, TimesTen installs
the Client driver and/or both the production version and the debug version of the
TimesTen Data Manager ODBC driver. The following table lists the TimesTen
ODBC drivers for UNIX platforms, assuming TimesTen is installed in the default
directory by user root.
Platform
Version
Location and Name
HP-UX
Production
/opt/TimesTen/TTinstance/lib/libtten.sl
HP-UX
Debug
/opt/TimesTen/TTinstance/lib/libttenD.sl
HP-UX
Client
/opt/TimesTen/TTinstance/lib/libttclient.sl
TimesTen Data Manager 6.0 Driver.
TimesTen Data Manager 6.0 Debug Driver.
TimesTen Client 6.0 Driver.
Solaris
Linux
Tru64
Production
/opt/TimesTen/TTinstance/lib/libtten.so
Solaris
Linux
Tru64
Debug
/opt/TimesTen/TTinstance/lib/libttenD.so
Solaris
Linux
Tru64
Client
/opt/TimesTen/TTinstance/lib/libttclient.so
AIX
Production
/usr/lpp/TimesTen/TTinstance/lib/libtten.a
TimesTen Data Manager 6.0 Driver.
TimesTen Data Manager 6.0 Debug Driver.
TimesTen Client 6.0 Driver.
TimesTen Data Manager 6.0 Driver.
Creating TimesTen Data Stores 31
Platform
Version
Location and Name
AIX
Debug
/usr/lpp/TimesTen/TTinstance/lib/libttenD.a
TimesTen Data Manager 6.0 Debug Driver.
AIX
Client
/usr/lpp/TimesTen/TTinstance/lib/libttclient.a
TimesTen Client 6.0 Driver.
TimesTen JDBC driver
The TimesTen JDBC driver uses the ODBC driver to access the TimesTen data
stores. For each JDBC method, the driver executes a set of ODBC functions to
perform the appropriate operation. Since the JDBC driver depends on ODBC for
all data store operations, the first step in using JDBC is to define a TimesTen data
store and the ODBC driver that will access it on behalf of JDBC.
JDBC is installed with the TimesTen Data Manager. JDBC allows Java
applications to issue SQL statements to TimesTen and process the results. JDBC
is the primary interface for data access in the Java programming language.
The JDBC API is implemented using a driver manager that can support multiple
drivers connecting to different databases. The TimesTen JDBC driver is
implemented using native methods to bridge to the TimesTen native API.
For a list of the functions supported by TimesTen, see the Oracle TimesTen InMemory Database Java Developer’s and Reference Guide.
JDBC driver manager
The JDBC driver manager (DriverManager class) keeps track of all the JDBC
drivers that have been loaded and are available to the Java Application. The
application may load several drivers and access each driver independently. For
example, both the TimesTen JDBC Client/Server driver and the TimesTen JDBC
direct driver can be loaded onto a machine. Then Java applications can access
data stores either on the local machine or a remote machine.
32 Oracle TimesTen In-Memory Database Operations Guide
Data source names
TimesTen data stores are accessed through Data Source Names (DSNs). A DSN
is a character-string name that identifies a TimesTen data store and a collection of
connection attributes that are to be used when connecting to the data store. On
Windows, the DSN also specifies the ODBC driver to be used to access the data
store.
Each DSN uniquely identifies a data store. However, a data store can be
referenced by multiple DSNs. Each of these DSNs can specify a different set of
connection attributes. This allows you to give convenient names to different
connection configurations for a single data store.
Note: According to the ODBC standard, when an attribute occurs multiple times
in a connection string, the first value specified is used, not the last value.
A DSN has the following characteristics:
• Its maximum length is 32 characters.
• It is composed of ASCII characters except for the following: []{},;?*=!@\
• It cannot contain spaces.
The rest of this section includes the following topics:
• User and system DSNs
• Data Manager and Client DSNs
• Connection attributes for Data Manager DSNs
• Exclusive and shared connections
• Thread programming with TimesTen
User and system DSNs
DSNs are resolved using a two-tiered naming system, consisting of user DSNs
and system DSNs:
• A user DSN can be used only by the user who created the DSN. On Windows,
user DSNs are defined from the User DSN tab of the ODBC Data Source
Administrator. On UNIX, user DSNs are defined in the file $HOME/.odbc.ini
or in a file named by the ODBCINI environment variable. This file is referred
to as the “user ODBC.INI file.” Although a user DSN is private to the user
who created it, it is only the DSN (the character-string name and its attributes)
that is private. The underlying data store can be referenced by other users’
user DSNs or by system DSNs.
• A system DSN can be used by any user on the machine on which the system
DSN is defined. On Windows, system DSNs are defined from the System
DSN tab of the ODBC Data Source Administrator. On UNIX, system DSNs
are defined in the file /var/TimesTen/sys.odbc.ini if TimesTen is installed
Creating TimesTen Data Stores 33
by user root, or install_dir/info/sys.odbc if TimesTen is installed by a
non-root user. This file is referred to as the “system ODBC.INI file.”
When looking for a specific DSN, TimesTen first looks for a user DSN with the
specified name. If no matching user DSN is found, TimesTen looks for a system
DSN with the specified name. If a user DSN and a system DSN with the same
name exist, TimesTen uses the user DSN. On UNIX, if there are multiple DSNs
with the same name in the same ODBC.INI file, TimesTen uses the first one in
the file.
Data Manager and Client DSNs
DSNs that use the TimesTen Data Manager (either the production version or the
debug version) are called “Data Manager DSNs.” DSNs that use the TimesTen
Client are called “Client DSNs.”
As described in Chapter 4, “How Applications Connect to Data Stores” in the
Oracle TimesTen In-Memory Database Architectural Overview, Data Manager
DSNs define what is referred to as a direct driver connection to the data store. A
Data Manager DSN refers to a data store using a path name. A data store path
name is a path name that specifies the location of the data store, for example:
C:\data\chns\AdminDS or /home/chns/AdminDS. This name is not a file name.
The actual files used by the data store have file suffixes, for example:
C:\data\chns\AdminDS.ds0 or /home/chns/AdminDS.log2. A Data Manager
DSN that refers to a given TimesTen data store must be defined on the same
system on which the data store resides. In addition, TimesTen creates
dsName.resn files for each data store. These files are used internally by
TimesTen for the creation of logs.
Note: If multiple Data Manager DSNs refer to the same data store, they must all
use exactly the same data store path name, even if some other path name
identifies the same location. For example, you cannot use a symbolic link to refer
to the data store in one DSN and the actual path name in another DSN. On UNIX,
you cannot place the data store on an NFS-mounted file system. On Windows,
you cannot use a mapped drive letter in the data store path name.
A Client DSN refers to a TimesTen data store indirectly by specifying a
hostname, DSN pair, where the hostname represents a machine on which
TimesTen Server Daemon is running and the DSN refers to a system DSN that is
defined on that host. We refer to this host as the “server machine” and the DSN as
a “Server DSN.”
On UNIX, all user DSNs (Client DSNs and/or Data Manager DSNs) created by a
specific user are defined in the same user ODBC.INI file. Similarly, all system
DSNs are defined in the same system ODBC.INI file.
34 Oracle TimesTen In-Memory Database Operations Guide
The following table indicates the types of DSN supported by TimesTen, whether
to create a user or system DSN and the location of the DSN.
DSN type
User or
System DSN?
Location of DSN
Data Manager
DSN
Can be a user or
system DSN
Located on the machine where the
data store resides.
Client DSN
Can be a user or
system DSN
Located on any local or remote
machine.
Server DSN
Must be a
system DSN
Located on the machine where the
data store resides.
The remainder of this chapter describes Data Manager DSNs and the connection
attributes that can be defined for them. For more information about Client DSNs
and Server DSNs, see Chapter 3, “Working with the TimesTen Client and
Server.”
Connection attributes for Data Manager DSNs
There are four types of TimesTen Data Manager attributes:
• Data store attributes are associated with a data store when it is
created and cannot be modified by subsequent connections.
• First connection attributes are set when a connection is made to an idle data
store (a data store with no connections) and persists for that connection and all
subsequent connections until the last connection to the data store is closed.
• General connection attributes are set by each connection and persist for the
duration of the connection. Different concurrent connections may use
different values.
• Cache Connect attributes allow you to enter the Oracle Service Identifier for
the Oracle instance from which data will be loaded into TimesTen.
Note: See Chapter 3, “Working with the TimesTen Client and Server” for a
description of the connection attributes that can be used with the TimesTen Client
ODBC driver.
For a complete description of each attribute, see Chapter 1, “Data Store
Attributes” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide.
On Windows, you specify data store attributes in the ODBC Data Source
Administrator.
Creating TimesTen Data Stores 35
On UNIX, you specify data store attributes in the ODBC.INI file. Attributes that
do not appear in the ODBC.INI file assume their default value.
Exclusive and shared connections
When in use, a TimesTen data store resides in virtual memory. Applications can
access a data store in either exclusive or shared mode. See ExclAccess in the
Oracle TimesTen In-Memory Database API and SQL Reference Guide.
• In Exclusive mode, only one application can connect to the data store at a
time, and that application can open only one connection to the data store at a
time. The data store resides within the address space of the connected
application, and therefore cannot be access by any other process.
• In Shared mode, multiple processes and threads can connect to the data store.
The data store resides in a region of shared memory, as provided by the
underlying operating system.
Applications using Exclusive mode may see better performance than those using
Shared mode, as TimesTen avoids certain overheads (fine-grain locking and
latching, for example) in Exclusive mode.
Thread programming with TimesTen
TimesTen supports multi-threaded application access to data stores. When a
connection is made to a data store, any thread may issue operations on the
connection.
To permit multiple connections to the same data store, multi-threaded
applications must set the ThreadSafe=1 connection attribute.
Typically, a thread issues operations on its own connection and therefore in a
separate transaction from all other threads. In environments where threads are
created and destroyed rapidly, better performance may be obtained by
maintaining a pool of connections. Threads can allocate connections from this
pool on demand to avoid the connect and disconnect overhead.
TimesTen allows multiple threads to issue requests on the same connection and
therefore the same transaction. These requests are serialized by TimesTen,
although the application may require additional serialization of its own.
TimesTen also allows a thread to issue requests against multiple connections,
managing activities in several separate and concurrent transactions on the same
or different data stores.
36 Oracle TimesTen In-Memory Database Operations Guide
Creating a DSN on Windows
This section describes how to set up a TimesTen data store on Windows. Before
you begin, read the “TimesTen ODBC and JDBC drivers” on page 30 to find out
what you’ll need to consider as you set up the data store.
For additional examples of setting up a data store, see “DSN examples” on page
42.
This section includes the following topics:
• Specify the ODBC driver
• Specify the DSN
• Specify the connection attributes
Specify the ODBC driver
Specify the ODBC driver in the ODBC Data Source Administrator.
Note: JDBC users need to specify the ODBC driver to be used by the JDBC
driver, as described in “TimesTen JDBC driver” on page 32.
1.
On the Windows Desktop, choose Start > Settings > Control Panel >
Administrative Tools > Data Sources (ODBC).
This opens the ODBC Data Source Administrator.
2.
Choose User DSN if you want to create a user DSN or System DSN if you want
to create a system DSN. You must have administrator privileges to create a
System DSN. For a description of user and system DSNs, see “User and system
DSNs” on page 33.
3.
Do one of the following:
• Select an existing data source and click Configure.
• Click Add, choose the appropriate TimesTen driver from the list. Click
Finish. This displays the TimesTen ODBC Setup dialog.
For a list of TimesTen ODBC drivers, see “TimesTen ODBC drivers” on page
30.
Specify the DSN
On the Data Store tab of the TimesTen ODBC Setup dialog, specify a data source
name and a data store pathname. The Data Store Path Name cannot reference a
mapped drive. See Figure 2.1.
Creating TimesTen Data Stores 37
Figure 2.1
Data Store
For an explanation of DSNs and data store pathnames, see “Data source names”
on page 33. The description field is optional.
Specify the connection attributes
Indicate the desired connection attributes under the First Connection, General
Connection tabs of the TimesTen ODBC Setup dialog. See Figure 2.2 and Figure
2.3.
For a description of the connection attributes, see Chapter 1, “Data Store
Attributes” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide.
Figure 2.2
First Connection Attributes
38 Oracle TimesTen In-Memory Database Operations Guide
Figure 2.3
General Connection Attributes
Click OK when you are finished.
Creating TimesTen Data Stores 39
Creating a DSN on UNIX
This section describes how to set up a TimesTen data store on UNIX. Before you
begin, be sure to read the “TimesTen ODBC and JDBC drivers” on page 30 to
find out what you’ll need to consider as you set up the data store.
For examples of defining a data store, see “DSN examples” on page 42.
This section includes the following topics:
• Create a user ODBC.INI file
• Specify the DSN
• Specify the ODBC driver
• Specify the data store path name
Create a user ODBC.INI file
On UNIX, user DSNs are defined in the file $HOME/.odbc.ini or in a file named
by the ODBCINI environment variable. This file is referred to as the “user
ODBC.INI file.” System DSNs are defined in the file /var/TimesTen/
sys.odbc.ini if TimesTen is installed by user root, or install_dir/info/
sys.odbc if TimesTen is installed by a non-root user. This file is referred to as
the “system ODBC.INI file.”
This file is referred to as the “system ODBC.INI file.” The syntax for the user
ODBC.INI file and the system ODBC.INI file is the same.
The system ODBC.INI file is created when TimesTen is installed on the machine.
Users must create their own user ODBC.INI file.
For more information about configuration files, see Chapter 10, “UNIX
Configuration Files” in the Oracle TimesTen In-Memory Database Operations
Guide.
Specify the DSN
Specify the data source name in the ODBC.INI file. The DSN appears inside
square brackets at the top of the DSN definition on a line by itself. For example:
[AdminDS]
Specify the ODBC driver
Note: JDBC users need to specify the ODBC driver to be used by the JDBC
driver, as described in “TimesTen JDBC driver” on page 32.
To set the TimesTen driver, specify the DRIVER parameter in the ODBC.INI file.
For example:
40 Oracle TimesTen In-Memory Database Operations Guide
[AdminDS]
DRIVER=install_dir/lib/libtten.so
For a list of TimesTen ODBC drivers, see “TimesTen ODBC drivers” on page
30.
Specify the data store path name
Specify the data store path name in the ODBC.INI file. For example:
DataStore=/users/robin/FixedDs
where FixedDs is the prefix for data store files. For more information, see “Data
source names” on page 33.
Note: On UNIX, the data store path name cannot reference an
NFS-mounted file system.
Set data store attributes
Specify data store attributes in your ODBC.INI file. Attributes that do not appear
in the ODBC.INI file assume their default value. See Chapter 1, “Data Store
Attributes” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide. For examples, see “DSN examples” on page 42.
Using environment variables in data store path names
You can use environment variables in the specification of the data store path
name and log file path name. For example, you can specify
$HOME/AdminDS for the location of the data store.
Environment variables can be expressed either as $varname or $(varname)
(the parentheses are optional). A backslash character (\) in the data store path
name quotes the next character.
Note: Environment variable expansion uses the environment of the process
connecting to the data store. Different processes may have different values for the
same environment variables and may therefore expand the data store path name
differently. Environment variables can only be used in the user ODBC.INI file.
They cannot be specified in the system ODBC.INI file.
Creating TimesTen Data Stores 41
DSN examples
This section provides additional examples of how to set up a data store:
• Setting up a temporary data store
• Creating multiple DSNs to a single data store
• Connecting to a data store without using a DSN
For each example, the Windows ODBC Data Source Administrator settings are
followed by the corresponding ODBC.INI entries for UNIX.
Setting up a temporary data store
Example 2.1
This example illustrates how to set up a temporary data store.
On Windows, you can use the settings in the TimesTen ODBC Setup dialog to set
up a temporary data store. See Figure 2.4 and Figure 2.5.
Figure 2.4
Data Store
42 Oracle TimesTen In-Memory Database Operations Guide
Figure 2.5
First Connection Attributes
To set up a temporary data store on UNIX, create the following entries in your
ODBC.INI file. For a list of drivers for all UNIX platforms, see the table on page
31.
The text in square brackets is the data source name.
[TempDs]
Driver=install_dir/lib/libtten.so
DataStore=/users/robin/TempDs
#this is a temporary data store
Temporary=1
#create data store if it is not found
AutoCreate=1
#log data store updates to disk
Logging=1
LogPurge=1
Note: A temporary data store cannot be backed up.
Creating multiple DSNs to a single data store
You can create two or more DSNs that refer to the same data store but have
different connection attributes. For example, an administrator might want to
connect to the data store with different settings than other users.
Example 2.2
This example creates two DSNs, AdminDs and OperationalDS. AdminDs is used
to perform administrative operations on the data store such as updating statistics
and creating indexes. The second data source name, OperationalDs, is used for
normal access to the data store.
Creating TimesTen Data Stores 43
For Windows, use the ODBC Data Source Administrator to define two DSNs as
shown in Figure 2.6 and Figure 2.7.
Figure 2.6
Data Store
Figure 2.7
First Connection Attributes
This example shows how to specify a data store with two DSNs on UNIX. It uses
the TimesTen Data Manager ODBC driver for Solaris.
The text in square brackets is the data source name.
[AdminDs]
Driver=install_dir/lib/libtten.so
Datastore=/users/robin/TTDS
#connect to data store in exclusive mode
ExclAccess=1
44 Oracle TimesTen In-Memory Database Operations Guide
#do not force log to disk on transaction commit
DurableCommits=0
[OperationalDs]
Driver=install_dir/lib/libtten.so
DataStore=/users/robin/TTDS
#create data store if it’s not found
AutoCreate=1
#do not wait if cannot connect to data store
WaitForConnect=0
#remove old log files at connect and checkpoint
LogPurge=1
Connecting to a data store without using a DSN
Using the ttIsql utility, you can connect to a data store without a predefined Data
Source Name by specifying:
• The name or path name of driver using the Driver attribute, and
• The data store path and filename prefix using DataStore attribute
On Microsoft Windows systems, the value of the Driver attribute should be the
name of the TimesTen ODBC Driver. For example, TimesTen Data Manager 6.0.
On UNIX systems, the value of the Driver attribute should be the pathname of
the TimesTen ODBC Driver shared library file. The file resides in the
install_dir/lib directory.
Example 2.3
C:\ ttIsql
ttIsql <c> 1996-2005, Oracle. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.
All commands must end with a semicolon character.
Command> connect "Driver=TimesTen Data Manager5.1;
DataStore=C:\sales\admin";
Creating TimesTen Data Stores 45
Specifying the size of a data store
This section includes the following topics:
• Temporary and permanent memory
• Changing data store size
• Receiving out-of-memory warnings
Temporary and permanent memory
TimesTen manages data store space using two separate memory partitions within
a single contiguous memory space. One partition contains permanent data and
the other contains temporary data.
• Permanent data includes the tables and indexes that make up a TimesTen data
store. When a data store is loaded into memory, the contents of the permanent
data partition are read from files stored on disk. The permanent data partition
is written to disk during checkpoint operations.
• Temporary data includes locks, cursors, compiled commands, and other
structures needed for command execution and query evaluation. The
temporary data partition is created when a data store is loaded into memory
and is destroyed when it is unloaded.
The connection attributes that control the size of the data store when it is in
memory are PermSize and TempSize. The PermSize attribute specifies the size of
the permanent data partition and the TempSize attribute specifies the size of the
temporary data partition.
See Chapter 1, “Data Store Attributes” in the Oracle TimesTen In-Memory
Database API and SQL Reference Guide for further description of these
attributes.
Changing data store size
The sizes of the permanent and temporary data partitions are set when a data
store is loaded into memory and cannot be changed while the data store is in
memory. To change the size of either partition, you must unload the data store
from memory and then reconnect using different values for the PermSize or
TempSize attributes. You can use the ttStatus utility to find processes connected
to the data store and stop them. Once you have made the change in data store
size, reload it into memory.
If the data store is configured for replication, you must also stop the replication
agent. You must reconfigure the data store sizes for all replicas of the data store.
Once you have made the change in data store size, read it into memory and restart
the replication agent and Cache Connect if it was connected.
• The permanent data partition can be increased in size, but it cannot be
decreased.
46 Oracle TimesTen In-Memory Database Operations Guide
• The temporary data partition can be either increased or decreased in size for
data stores that do not participate in replication.
To unload a data store from memory, you must close all active connections to the
data store and the RAM policy of the data store must be set to manual or inUse.
See “Specifying a RAM policy” on page 48 for more information about RAM
policy settings.
You must also make sure that you have a shared memory segment that is large
enough to hold the data store. In general, the minimum size of this shared
memory segment should be:
PermSize + TempSize + LogBuffSize +7MB overhead
For more details, see "Installation prerequisites" in the TimesTen Installation
Guide and the descriptions of the attributes TempSize and PermSize in the
TimesTen Reference Guide.
Receiving out-of-memory warnings
TimesTen provides two General Connection attributes that determine when a low
memory warning should be issued: PermWarnThreshold and
SqlQueryTimeout. Both attributes take a percentage value.
To receive out-of memory warnings, applications must call the built-in procedure
ttWarnOnLowMemory.
These attributes also set the threshold for SNMP warning. See the chapter,
“Diagnostics through SNMP Traps” in the Oracle TimesTen In-Memory
Database API and SQL Reference Guide.
Creating TimesTen Data Stores 47
Specifying a RAM policy
TimesTen allows you to specify a RAM policy that determines when data stores
are loaded and unloaded from main memory. To set the RAM policy, use the
ttAdmin utility.
For each data store you can have a different RAM policy. The policy options are:
• In Use. The data store is loaded into memory when the first connection to the
data store is opened, and it remains in memory as long as it has at least one
active connection. When the last connection to the data store is closed, the
data store is unloaded from memory. This is the default policy.
• InUse with RamGrace. The data store is loaded into memory when the first
connection to the data store is opened, and it remains in memory as long as it
has at least one active connection. When the last connection to the data store is
closed, the data store remains in memory for a “grace period.” The data store
is unloaded from memory only if no processes have connected to the data
store for the duration of the grace period. The grace period can be set or reset
at any time. It is only in effect and stays in effect until the next time the grace
period is changed.
• Always.The data store stays in memory at all times. If the machine on which
the data store resides is rebooted, the data store reloads into memory when the
TimesTen daemon is started, generally at boot time.
• Manual. The data store is manually loaded and unloaded by system
administrators using the ttAdmin utility.
48 Oracle TimesTen In-Memory Database Operations Guide
Configuring a diskless data store
TimesTen allows you to create and use data stores that do not create disk files of
any kind. This form of operation is called “diskless operation,” and can be used
on machines that have no writable file systems. To enable diskless operation for
your installation, you must:
• Inform the TimesTen daemon that it is to operate in diskless mode. You must
set the -diskless option in the ttendaemon.options file. See Chapter 4,
“Working with the Oracle TimesTen Data Manager Daemon” in the Oracle
TimesTen In-Memory Database Operations Guide.
• Use the following data store connection attributes:
– Set Logging to diskless mode (2) or use no logging (0).
– Set DataStore to any path, even invalid or non existing ones. TimesTen
uses the value of DataStore as a unique identifier.
– Turn DurableCommits off (0)
– Set Locklevel to data store-level locking (1)
– Set Temporary to temporary data store mode (1).
Note: Diskless operations are only supported on UNIX systems.
TimesTen supports replication between diskless nodes and other nodes. For
details about how to enable replication with diskless operation, see the TimesTen
Replication Guide.
Creating TimesTen Data Stores 49
Copying, migrating, backing up and restoring a data store
The TimesTen utilities for copying, backing up, restoring and migrating a data
store allow you to:
• Copy an entire data store or a single table.
• Migrate a data store between releases of TimesTen or different hardware
platforms.
• Take a snapshot of a data store and then restore it.
• Add rows of data to a table.
• Rename the owner of tables in a data store
To migrate a data store between releases of TimesTen, use the ttMigrate utility.
This utility saves tables and indexes from a TimesTen data store into a binary file.
The tables and indexes can then be restored into another TimesTen data store.
This allows you to migrate data between TimesTen releases.
To migrate a data store between hardware platforms, use the ttBulkCp utility.
This utility saves the rows of a table to an ASCII file. It allows you to copy a
single table between data stores, including between data stores from different
releases of TimesTen or between data stores on different hardware platforms.
To add rows of data to an existing table, use the ttBulkCp utility. You can save
data to an ASCII file and use the ttBulkCp utility to load the data rows into a
table in a TimesTen data store. The rows you are adding must contain the same
number of columns as the table, and the data in each column must be of the type
defined for that column. Because the ttBulkCp utility works on data stored in
ASCII files, you can also use this utility to import data from other applications,
provided the number of columns and data types are compatible with those in the
table in the TimesTen data store and that the file found is compatible with
ttBulkCp.
To take a snapshot of a data store and later restore that data store in the exact
same state, use the ttBackup and ttRestore utilities or the ttBackup and
ttRestore utilities C functions.
To rename the owner of tables in a data store, use the ttMigrate utility. When
restoring tables, you can use the -rename option to rename the owner of tables.
Backing up and restoring a data store
TimesTen’s backup and restore facility allows you to create backups of TimesTen
data stores and restore the data store at a later time. The primary use for the
backup and restore facility is to allow the restoration of a recent state of a data
store that has been lost.
Every data store backup contains the information needed to restore the data store
as it existed at a the backup point; the time the backup began. Restoration of a
data store from a given backup restores the modifications of all transactions that
committed before the backup point.
50 Oracle TimesTen In-Memory Database Operations Guide
In this release, TimesTen supports both full and incremental backups. An
incremental backup moves the backup point of an existing backup forward in
time by augmenting the backup with all of the log records created since its
backup point.
TimesTen writes a data store backup to a location specified by a backup path,
which consists of a directory name and an optional basename. You must specify
the backup directory and basename when the backup is created. The basename
defaults to the basename of the data store itself if you do not specify a basename.
Note: You must not manually change the contents of the backup directory. The
addition, removal, or modification of any file in the backup directory, except for
modifications made by ttBackup and ttRestore themselves, may compromise the
integrity of the backup and restoration of the data store from the backup may not
be possible.
TimesTen also allows stream backups. A stream backup writes the data store
backup file to stdout.
A set of files containing backup information for a given data store, residing at a
given backup path is referred to as a backup instance. A given backup instance
must be explicitly enabled for incremental backups.
An incremental backup can only augment an existing incremental-enabled
backup of the same data store. Restoring a data store from a backup causes all
existing incremental-enabled backups of this data store to become incremental
backups to become incremental-disabled.
TimesTen supports the creation of up to eight incremental-enabled backup
instances for each data store. If you attempt to start an incremental backup in a
ninth backup path, TimesTen returns an error. Incremental backups are supported
only for permanent disk-logging data stores.
Information about incremental backups is not retained across data store recovery
or restoration. Existing backup instances continue to be usable for restoring the
data store, but incremental backups to those instances will have to be reenabled.
A backup operation is atomic: If it completes successfully, it will produce a
backup that can be used to restore a data store to the state of its backup point. If it
fails for any reason, it leaves the files of the existing backup (if any) intact and its
backup point unchanged.
Note: For full backups, you must have enough disk space available to hold both
the existing backup and the new backup, until the new backup succeeds.
The files of the existing backup may be modified by a failed full or incremental
backup, but not in a way that compromises the ability to restore from them.
Creating TimesTen Data Stores 51
An incremental backup typically completes much faster than a full backup, as it
has less data to copy. The performance gain of incremental backups over full
backups comes at the cost of increased disk usage and longer restoration times.
Use incremental backups in concert with full backups in order to achieve a
balance between backup time, disk usage, and restoration time.
The backup types supported by TimesTen are:
Backup Type
File or
Stream
Full or
Incremental
Incremental
-enabled
Comments
fileFull
File
Full
No
Default
fileFullEnable
File
Full
Yes
fileIncremental
File
Incremental.
Yes
Fails if incremental
backup not possible.
fileIncrOrFull
File
Either
Yes
Performs
fileIncremental if
possible;
fileFullEnable
otherwise.
streamFull
Stream
Full
No
incrementalStop
None
None
No
Takes no backup;
just disables existing
incremental-enabled
backup.
For details on using TimesTen’s backup and restore facility, see these references
in the Oracle TimesTen In-Memory Database API and SQL Reference Guide.
52 Oracle TimesTen In-Memory Database Operations Guide
3
Working with the TimesTen Client
and Server
To access TimesTen data stores on remote machines, applications can use the
TimesTen ODBC or JDBC Client driver and TimesTen Server Daemon. Using
the TimesTen Client, applications written to use the TimesTen Data Manager can
connect transparently to TimesTen data stores on any remote or local machine
that has the TimesTen Server Daemon and Data Manager installed.
You can also install the TimesTen Client and TimesTen Server on the same
machine and use them to access TimesTen data stores on the local machine. On
Solaris and HP-UX, this is useful if you have a 32-bit client application that
needs to access a 64-bit data store on the same machine. You can create a client/
server connection between any combination of 32/64 bits RedHat Linux, Solaris,
and HP-UX platforms.
The TimesTen Server is a process that runs on a server machine. The TimesTen
ODBC or JDBC Client is a thin driver that communicates with the TimesTen
Server.
On Windows, you can either link the Client applications with the driver manager
or directly with the TimesTen Client driver.
On UNIX, you must link Client applications directly with the TimesTen Client
driver.
For UNIX, there are Client/Server versions of some TimesTen utilities: ttIsqlCS,
ttBulkCpCS, ttMigrateCS and ttSchemaCS.
For details on compiling TimesTen applications, see the Oracle TimesTen InMemory Database Java Developer’s and Reference Guide or the Oracle
TimesTen In-Memory Database C Developer’s and Reference Guide.
The main topics in this chapter are:
• Client/Server Communication
• Configuring TimesTen Client and Server
• Running the TimesTen Server Daemon
• Defining Server DSNs
• TimesTen Client connection attributes
• Creating and configuring Client DSNs on Windows
53
• Creating and configuring Client DSNs on UNIX
• Accessing a remote data store on UNIX
• Troubleshooting Client/Server problems
54 Oracle TimesTen In-Memory Database Operations Guide
Client/Server Communication
Each TimesTen Client connection requires one Server process. By default, a
Server process is spawned at the time a Client requests a connection. By setting
the -serverPool option in the ttendaemon.options file on the Server machine,
you can pre-spawn a pool of Server processes. See “Prespawning TimesTen
Server processes” on page 84,” for details.
When using TimesTen Client/Server there are three ways the TimesTen Client
can communicate with the TimesTen Server.
TCP/IP Communication
By default, the TimesTen Client communicates with the TimesTen Server
daemon using TCP/IP sockets. This is the only form of communication available
when the TimesTen Client and Server are installed on different machines.
Shared memory communication
If both the TimesTen Client and Server are installed on the same machine,
applications using the TimesTen Client ODBC driver may improve performance
by using a shared memory segment for inter-process communication (IPC).
Using a shared memory segment allows for the best performance, but consumes
more memory. To use a shared memory segment as communication, you must set
the server options in the ttendaemon.options file. See “Using shared memory
for Client/Server IPC” on page 85. You must also define the Network Address of
the logical server as ttShmHost. See “Creating and configuring Client DSNs on
Windows” on page 59 or “Creating and configuring Client DSNs on UNIX” on
page 67.
Note: TimesTen supports a maximum of 16 different instances of the shared
memory IPC-enabled server. If an application tries to connect to more than 16
different shared memory segments it receives the ODBC error “Cannot connect
to more than 16 SHMIPC-enabled TimesTen Servers.”
UNIX domain socket communication
On certain UNIX platforms, if both the TimesTen Client and Server are installed
on the same machine, you can use UNIX domain sockets for communication.
Using a shared memory segment allows for the best performance, but greater
memory usage. Using UNIX domain sockets allows for improved performance
over TCP/IP, but with less memory consumption than a shared memory segment
connection. See the section in this chapter that describes how to create a Client
DSN for your platform. To use domain sockets, you must define the Network
Address of the logical server as ttLocalHost. See “Creating and configuring
Client DSNs on UNIX” on page 67.
Working with the TimesTen Client and Server 55
Configuring TimesTen Client and Server
Before configuring the TimesTen Client and Server, read the “TimesTen ODBC
and JDBC drivers” and “Data source names” sections of Chapter 2, “Creating
TimesTen Data Stores." To connect a TimesTen application to a TimesTen data
store using TimesTen Client and Server:
1.
Install the TimesTen Server on the machine on which the TimesTen data store
resides. This machine is called the “server machine.” For information on how to
install the TimesTen Server, see the Oracle TimesTen In-Memory Database
Installation Guide. During installation, choose to have the TimesTen Server
automatically started.
2.
Install the TimesTen Client on the machine where the Client application resides.
This machine is called the “client machine.” For information on how to install the
TimesTen Client, see the Oracle TimesTen In-Memory Database Installation
Guide.
3.
For JDBC, install the Java Developer’s Kit (JDK) on the client machine, where
the Java application(s) will be running and set up the environment variables
(CLASSPATH and LIBRARY PATH) on the client machine. See Chapter 1,
“Configuring the Java Development Environment in the Oracle TimesTen InMemory Database Java Developer’s and Reference Guide for details.
4.
On the server machine, create and configure a Server DSN corresponding to the
TimesTen data store. See “Defining Server DSNs” on page 58.
5.
On the client machine, create and configure a Client DSN corresponding to the
Server DSN. See “Creating and configuring Client DSNs on UNIX” on page 67
and “Creating and configuring Client DSNs on Windows” on page 59.
6.
Set TimesTen Client connection attributes. See Chapter 1, “Data Store
Attributes” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide.
7.
For C client applications, link as described in “Linking options” in the Oracle
TimesTen In-Memory Database C Developer’s and Reference Guide.
56 Oracle TimesTen In-Memory Database Operations Guide
Running the TimesTen Server Daemon
The TimesTen Server daemon is a subdaemon of the TimesTen daemon. If the
TimesTen Server is installed on your machine, the TimesTen Server daemon
starts automatically every time the TimesTen daemon is started and stops
automatically every time the TimesTen daemon is stopped on your machine.
The TimesTen Server daemon handles request from applications linked with the
TimesTen Client ODBC driver.
By default, the 32-bit version of TimesTen Server Daemon listens on TCP port
number 16002 and the 64-bit version listens on 16003. System administrators can
change the port number during installation to avoid conflicts or for security
reasons. The port range is from 1 - 65535. To connect to the TimesTen Server
Daemon, Client DSNs are required to specify the port number as part of the
logical server name definition or in the connection string.
On Windows, the TimesTen Server daemon is run as user SYSTEM. On UNIX,
the TimesTen Server daemon is run as the instance administrator (user root,
unless the instance is installed as non-root).
For instructions on modifying TimesTen Server Daemon options, see “Modifying
the TimesTen Server daemon options” in Chapter 4 of the Oracle TimesTen InMemory Database Operations Guide.
Server informational messages
The TimesTen Server records “connect,” “disconnect” and various warning, error
and informational entries in log files.
On Windows, these application messages can be accessed with the Event Viewer.
On UNIX, the TimesTen Server logs messages to a syslog facility. You can
define the facility used by syslog by setting the -facility option in the
ttendaemon.options file or specify an output file by using the -f option in the
ttendaemon.options file. See “Modifying the informational message options
on UNIX” on page 82. The syslog facility allows messages to be routed in a
variety of ways, including recording them to one or more files. The disposition of
messages is under the control of the configuration file /etc/syslog.conf. See
the operating system documentation for syslog.conf or syslogd for
information on how to configure this file. Message files can grow to be quite
large. Prune them periodically to conserve disk space.
Working with the TimesTen Client and Server 57
Defining Server DSNs
Server DSNs correspond to data stores that are accessed by a TimesTen Server
Daemon. You can add or configure a Server DSN while the TimesTen Server is
running.
A Server DSN is a TimesTen data manager system DSN. For a description of
DSNs and instructions on creating them, see “Creating a DSN on Windows” on
page 37 or “Creating a DSN on UNIX” on page 40.
TimesTen Client connection attributes
This section discusses the connection attributes used by the TimesTen Client
driver. You can configure attributes as part of the Client DSN definition or you
can configure connection attributes at runtime in the connection string that is
passed to the ODBC SQLDriverConnect function or the URL string that is
passed to the JDBC DriverManager.getConnection method.
The Authenticate, DataStore, and ThreadSafe Data Manager attributes are not
allowed in the TimesTen Client connection string.
Note: The TimesTen Client allows TimesTen Data Manager attributes to be
passed in as part of the connection or URL string. However, the Client ignores
any Data Manager attributes specified in the ODBC.INI file as part of the
TimesTen Client DSN definition.
For a complete description of the TimesTen Client connection attributes, see
Chapter 1, “Data Store Attributes” in the Oracle TimesTen In-Memory Database
API and SQL Reference Guide.
58 Oracle TimesTen In-Memory Database Operations Guide
Creating and configuring Client DSNs on Windows
On Windows, use the ODBC Data Source Administrator to configure logical
server names and to define Client DSNs.
This section includes the following topics:
• Creating and configuring a logical server name
• Creating a Client DSN on Windows
• Setting the timeout interval and authentication
• Deleting a server name
• Accessing a remote data store on Windows
• Testing connections
Creating and configuring a logical server name
To create and configure a logical server name:
1.
On the Windows Desktop, choose Start > Settings > Control Panel >
Administrative Tools > Data Sources (ODBC).
This opens the ODBC Data Source Administrator.
2.
Click User DSN or System DSN.
3.
Select a TimesTen Client DSN and click Configure. If no Client DSN exists,
click Add, select TimesTen Client 6.0 and click Finish. This opens the
TimesTen Client DSN Setup dialog.
4.
Click Servers. This opens the TimesTen Logical Server List dialog.
5.
Click Add. This opens the TimesTen Logical Server Name Setup dialog.
6.
In the Server Name field, enter a logical server name.
7.
In the Description field, enter an optional description for the server.
8.
In the Network Address field, enter the host name or IP address of the server
machine. The Network Address must be one of:
Type of Connection
Network Address
Local Client/Server connection that
uses shared memory for inter-process
communication
ttShmHost
Remote Client/Server connection
The name of the machine where the
TimesTen Server is running. For
example, server. mycompany.com
Working with the TimesTen Client and Server 59
9.
In the Network Port field, TimesTen displays the port number on which the
TimesTen Logical Server Listens by default. If the TimesTen Server is listening
on a different port, enter that port number in the Network Port field.
For example:
10. Click OK, then click Close in the TimesTen Logical Server List dialog to finish
creating the logical server name.
Creating a Client DSN on Windows
To define a TimesTen Client DSN:
1.
On the Windows Desktop, choose Start > Settings > Control Panel >
Administrative Tools > Data Sources (ODBC).
This opens the ODBC Data Source Administrator.
2.
Choose either User DSN or System DSN. For a description of User DSNs and
System DSNs see “Data source names” on page 33.
60 Oracle TimesTen In-Memory Database Operations Guide
3.
Click Add. This opens the Create New Data Source dialog.
4.
Choose TimesTen Client 6.0. Click Finish. This opens the TimesTen Client
DSN Setup dialog.
5.
In the Client DSN field, enter a name for the Client DSN.
• The name must be unique to the current list of defined DSNs on the machine
where the Client application resides and can contain up to 32 characters. To
avoid potential conflicts, you may want to use a consistent naming scheme
that combines the logical server name with the name of the Server DSN. For
example, a corporation might have Client DSNs named Boston_Accounts
and Chicago_Accounts where Boston and Chicago are logical server names
and Accounts is a Server DSN.
6.
In the Description field, enter an optional description for the Client DSN.
7.
In the Server Name or Network Address field, specify the logical server or
network address of the server machine.
• The name can be a host name, IP address or logical server name. The logical
server names defined on the client machine can be found in the drop-down
list. To define logical server names, click Servers.
• If you do not specify a logical server name in this field, the TimesTen Client
assumes that the TimesTen Server Daemon is running on the default TCP/IP
port number. Therefore, if your Server is running on a port other than the
default port and you do not specify a logical server name in this field, you
must specify the port number in the ODBC connection string, using the
TCP_Port attribute.
Working with the TimesTen Client and Server 61
For more information on defining logical server names, see “Creating and
configuring a logical server name” on page 59.
8.
In the Server DSN field, enter the Server DSN corresponding to the data store
that the Client application will access.
• If you do not know the name of the Server DSN, click Refresh to obtain a list
of Server DSNs that are defined on the machine specified in the Server Name
or Network Address field. Select the Server DSN from the drop-down list.
• You must have a network connection to the machine where the TimesTen
Server is running.
Enter a name for the Client data source.
Enter a description for the data source.
Enter the name of the TimesTen Server that
has the data source you want to access.
Enter the name of the TimesTen Server data
source you want to access on the server.
Setting the timeout interval and authentication
For a description of the Timeout, UID and PWD attributes, see Chapter 1, “Data
Store Attributes” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide.
To set the timeout interval and authentication:
1.
In the User ID field, you can enter a user name that is defined on the server
machine. If the server DSN that corresponds to this client DSN is defined with
Authenticate=1, you must provide a user name either in this field or in the
connection string of every application that uses this client DSN. If the server
62 Oracle TimesTen In-Memory Database Operations Guide
DSN is defined with Authenticate=0, then TimesTen ignores the value entered
in this field, unless Access Control is enabled In that case the User ID is required.
Enter the User ID and Password
required by the TimesTen Server
for authentication.
Enter the number of seconds that
TimesTen should wait for a
connection to the Server DSN
before timing out.
2.
In the Password field, you can enter the password that corresponds to the user
ID. Alternatively, you can enter an encrypted password in the PwdCrypt field. If
the server DSN that corresponds to this client DSN is defined with
Authenticate=1, you must provide the password either in this field or in the
connection string of every application that uses this client DSN. If the server
DSN is defined with Authenticate=0, then TimesTen ignores the value entered
in this field, unless Access Control is enabled In that case the Password is
required.
3.
In the Timeout Interval field, enter the interval time in seconds. You can enter
any non-negative integer. A value of 0 indicates that Client/Server operations
should not timeout. The default is 60 seconds. The maximum is 99,999 seconds.
4.
Click OK to save the setup.
Deleting a server name
To delete a server name:
1.
On the Windows Desktop on the Client machine, choose Start > Settings >
Control Panel.
2.
Double click ODBC. This opens the ODBC Data Source Administrator.
3.
Click either User DSN or System DSN.
4.
Select a TimesTen Client DSN and click Configure. This opens the TimesTen
Client DSN Setup dialog.
5.
Click Servers. This opens the TimesTen Logical Server List dialog.
6.
Select a server name from the TimesTen Servers list.
7.
Click Delete.
Working with the TimesTen Client and Server 63
Accessing a remote data store on Windows
In this example, the TimesTen Client machine is client.mycompany.com. The
Client application is accessing the Server DSN on the remote server machine,
server.mycompany.com. The logical name of the server is ttserver_logical.
Example 3.1
1.
On the server machine server.mycompany.com, use the ttStatus utility to verify
that the TimesTen Server Daemon is running and to verify the port number it is
listening on.
2.
Using the procedure in “Defining Server DSNs” on page 58, verify that the
Server DSN, RunData60, is defined as a System DSN on
server.mycompany.com.
3.
On the Client machine, client.mycompany.com, create a logical Server Name
entry for the remote TimesTen Server. In the TimesTen Logical Server Name
Setup dialog:
• In the Server Name field, enter ttserver_logical.
• In the Network Address field, enter server.mycompany.com.
• In the Network Port field, enter 16002. This is the default port number for
TimesTen Release 6.0. This value should correspond to the value displayed by
ttStatus in Step 1.
See “Creating and configuring a logical server name” on page 59 for the
procedure to open the TimesTen Server Name dialog and for more details.
4.
On the Client machine, client.mycompany.com, create a Client DSN that
corresponds to the remote Server DSN, RunData60. In the TimesTen Client
DSN Setup dialog, enter the following values:
• In the Client DSN field, enter RunDataCS60.
• In the Server Name or Network Address field, enter ttserver_logical.
• In the Description field, enter a description for the server. Entering data into
this field is optional.
• In the Server DSN field, enter RunData60.
5.
Run the Client application from the machine client.mycompany.com using the
Client DSN, RunDataCS60. The example below uses the ttIsqlCS program
installed with TimesTen Client.
ttIsqlCS connStr “DSN=RunDataCS60”
Example 3.2
This example describes how to access a TimesTen Server that is listening on a
port numbered other than the default port number.
Let us consider the Network Address of the TimesTen Server is
server.mycompany.com and the Server is listening on Port 22222. The following
methods can be used to connect to a Server DS:
64 Oracle TimesTen In-Memory Database Operations Guide
1.
Define the logical server name logical_server with server.mycompany.com
as the Network Address and 22222 as the Network Port. Define a Client DSN
with logical_server as the Server name, Server_DSN as the Server DSN. And
execute the command:
ttIsqlCS -connStr “DSN=Client_DSN”
2.
Alternatively, define the logical server name logical_server with
server.mycompany.com as the Network Address and the default port
number as the Network Port. Define a Client DSN with logical_server as the
Server name, Server_DSN as the Server DSN. Overwrite the port number in the
command:
ttIsqlCS -connStr “DSN=Client_DSN; TCP_Port=22222”
3.
Alternatively, define the Server in the connection string. In this case you do not
need to define a Client DSN, nor a logical server name.
ttIsqlCS -connStr “TTC_Server=server.mycompany.com;
TTC_Server_DSN=Server_DSN; TCP_Port=22222”
Testing connections
To test Client application connections to TimesTen data stores:
1.
On the Windows Desktop, choose Start > Settings > Control Panel.
2.
Double click ODBC. This opens the ODBC Data Source Administrator.
3.
Click User DSN or System DSN.
4.
Select the TimesTen Client DSN whose connection you want to test and click
Configure. This opens the TimesTen Client DSN Setup dialog.
Click here to attempt a connection to the
TimesTen Server.
Click here to attempt a connection to the TimesTen data
source on the TimesTen Server.
Working with the TimesTen Client and Server 65
5.
Click Test TimesTen Server Connection to test the connection to TimesTen
Server.
The ODBC Data Source Administrator attempts to connect to TimesTen Server
Daemon and displays messages to indicate if it was successful. During this test
TimesTen Client verifies that:
• ODBC, Windows sockets and TimesTen Client are installed on the client
machine.
• The server specified in the Server Name or Network Address field of the
TimesTen Client DSN Setup dialog is defined and the corresponding machine
exists.
• The TimesTen Server Daemon is running on the server machine.
6.
Click Test Data Source Connection to test the connection to the Server DSN.
The ODBC Data Source Administrator attempts to connect to the TimesTen
Server DSN and displays messages to indicate whether it was successful.
During this test, TimesTen Client verifies that:
• The Server DSN specified in the Server DSN field is defined on the server
machine.
• A Client application can connect to the Server DSN.
66 Oracle TimesTen In-Memory Database Operations Guide
Creating and configuring Client DSNs on UNIX
On UNIX, you define logical server names by editing the TTCONNECT.INI file
and you define client DSNs by editing the user ODBC.INI file (for user DNS) or
the system ODBC.INI file (for system DSNs). For a description of user and
system DSNs, see “Data source names” on page 33.
This section includes the following topics:
• Searching for a DSN
• Creating and configuring a logical server name
• Creating a Client DSN
Searching for a DSN
When TimesTen looks for a specific DSN, it looks in the following locations in
this order:
1.
The file referenced by the ODBCINI environment variable, if it is set
2.
The .odbc.ini file in the user’s home directory, if the ODBCINI environment
variable is not set
3.
The file referenced by the SYSODBCINI environment variable, if it is set
4.
One of the following, if the SYSODBCINI environment variable is not set:
– The InstallDir/info/sys.odbc.ini file for a nonroot installation
– The /var/TimesTen/InstanceName/sys.odbc.ini file for a root
installation
5.
The /var/TimesTen/sys.odbc.ini file, if the SYSODBCINI environment
variable is not set
Creating and configuring a logical server name
You define logical server names in the /var/TimesTen/instance/
sys.ttconnect.ini file or in a file named by the SYSTTCONNECTINI
environment variable. This file is referred to as the TTCONNECT.INI file. The
file contains a description, a network address and a port number.
The Network Address must be one of:
Type of Connection
Network Address
Local Client/Server connection that
uses UNIX domain sockets
ttLocalHost
Working with the TimesTen Client and Server 67
Type of Connection
Network Address
Local Client/Server connection that
uses shared memory for inter-process
communication
ttShmHost
Remote Client/Server connection
The name of the machine where the
TimesTen Server is running. For
example, server. mycompany.com
Examples
Example 3.3
Below is an example from a TTCONNECT.INI file that defines a logical server
name, ttserver_logical, for a TimesTen Server daemon running on the
machine server.mycompany.com and listening on port 16002. The instance
name of the TimesTen installation is “tt60.”
[ttserver_logical]
Description=TimesTen Server 6.0
Network_Address=server.mycompany.com
TCP_Port=16002
Example 3.4
If both the client and server are on the same UNIX machine, applications using
the TimesTen Client ODBC driver may improve performance by using UNIX
domain sockets for communication.
The logical server name must also define the port number on which the TimesTen
Server Daemon is listening so that multiple instances of the same version of
TimesTen Server Daemon can be run on the same machine. To achieve this, the
logical server name definition in TTCONNECT.INI file might look like:
[LocalHost_tt60]
Description=
Local TimesTen Server TimesTen release 6.0 through domain
sockets
Network_Address=ttLocalHost
TCP_PORT=16002
Example 3.5
If both the client and server are on the same machine, applications can use shared
memory for inter-process communication. This may result in the best
performance.
The logical server name must also define the port number on which the TimesTen
Server Daemon is listening in order to make the initial connection. To achieve
this, the logical server name definition in TTCONNECT.INI file might look like:
68 Oracle TimesTen In-Memory Database Operations Guide
[ShmHost_tt60]
Description=
Local TimesTen Server TimesTen release 6.0 through shared memory
Network_Address=ttShmHost
TCP_PORT=16002
Creating a Client DSN
In the ODBC Data Sources section of the ODBC.INI file, add an entry for the
Client DSN. Each entry in this section lists the data source and the name of the
ODBC driver that the data source uses. Use the following format for data source
entries.
[ODBC Data Sources]
data-source-name=name-of-ODBC-driver
For example, to add the RunDataCS_tt60 data source and associate it with the
TimesTen Client ODBC driver, make the following entry in the ODBC Data
Sources section of the ODBC.INI file.
[ODBC Data Sources]
RunDataCS_tt60=TimesTen Client 6.0
After the ODBC Data Sources section, add an entry to specify the connection
attributes for each data source you have defined. Each data source listed in the
ODBC Data Sources section of the ODBC.INI file requires a data source
specification section.
The following is an example specification of the TimesTen Client example DSN
RunData_tt60.
[RunDataCS_tt60]
TTC_Server=ttserver_logical
TTC_Server_DSN=RunData_tt60
For a description of the Client DSN attributes used in the ODBC.INI file, see
Chapter 1, “Data Store Attributes” in the Oracle TimesTen In-Memory Database
API and SQL Reference Guide.
Working with the TimesTen Client and Server 69
Accessing a remote data store on UNIX
In this example, the TimesTen Client application machine is a 32-bit Solaris
machine, client.mycompany.com. The Client application is accessing the Server
DSN RunData_tt60 on the remote server machine, another 32-bit Solaris
machine, server.mycompany.com. The logical name of the server is
ttserver_logical. The instance name of the TimesTen installation is “tt60.”
Example 3.6
1.
2.
On the server machine server.mycompany.com, use the ttStatus utility to verify
that the TimesTen Server is running and to verify the port number on which it is
listening.
Verify that the Server DSN RunData_tt60 exists in the system ODBC.INI file on
server.mycompany.com.
There should be an entry in the ODBC.INI file as follows:
[RunData_tt60]
Driver=/opt/TimesTen/tt60/lib/libtten.so
DataStore=/var/TimesTen/tt60/server/RunData_tt60
3.
Create a logical Server Name entry for the remote TimesTen Server in the
TTCONNECT.INI file on client.mycompany.com.
[ttserver_logical]
# This value for TCP_Port should correspond to the
# value reported by ttStatus when verifying that the
# server is running
Network_Address=server.mycompany.com
TCP_Port=16002
See “Creating and configuring Client DSNs on UNIX” on page 67 for
information on the creating a TTCONNECT.INI file.
4.
On the Client machine, client.mycompany.com, create a Client DSN
corresponding to the remote Server DSN, RunData_tt60.
There should be an entry in the ODBC.INI file as follows:
[RunDataCS_tt60]
TTC_SERVER=ttserver_logical
TTC_SERVER_DSN=RunData_tt60
See “User and system DSNs” on page 33 for information on the location of the
proper ODBC.INI file.
5.
Run the Client application from the machine client.mycompany.com using the
Client DSN, RunDataCS_tt60. The example below uses the ttIsql program that
is installed with TimesTen Client.
ttIsqlCS -connStr "DSN=RunDataCS_tt60”
Example 3.7
This example describes how to access a TimesTen Server that is listening on a
port numbered other than the default port number.
70 Oracle TimesTen In-Memory Database Operations Guide
Let us consider the Network Address of the TimesTen Server is
server.mycompany.com and the Server is listening on Port 22222. The following
methods can be used to connect to a Server DS:
1.
Define the logical server name logical_server with server.mycompany.com
as the Network Address and 22222 as the Network Port. Define a Client DSN
with logical_server as the Server name, Server_DSN as the Server DSN. And
execute the command:
ttIsqlCS -connStr “DSN=Client_DSN”
2.
Alternatively, define the logical server name logical_server with
server.mycompany.com as the Network Address and the default port
number as the Network Port. Define a Client DSN with logical_server as the
Server name, Server_DSN as the Server DSN. Overwrite the port number in the
command:
ttIsqlCS -connStr “DSN=Client_DSN; TCP_Port=22222”
3.
Alternatively, define the Server in the connection string. In this case you do not
need to define a Client DSN, nor a logical server name.
ttIsqlCS -connStr “TTC_Server=server.mycompany.com;
TTC_Server_DSN=Server_DSN; TCP_Port=22222”
Testing connections
To test Client application connections to TimesTen data stores:
1.
Verify that the client machine can access the server machine.
2.
Run ping from the client machine to see if a response is received from the server
machine.
3.
Verify that the TimesTen Server Daemon is running on the server machine.
• Use telnet to connect to the port on which the TimesTen Server Daemon is
listening. For example:
telnet server.mycompany.com 16002
• If you successfully connect to the TimesTen Server Daemon, you will see a
message similar to:
Connected to server.mycompany.com
• If the server machine responds to a command, but TimesTen Server Daemon
does not, the TimesTen Server Daemon may not be running. In the case of a
failed connection, you will see a message similar to:
telnet: Unable to connect to remote host:
Connection refused
• Use the ttStatus utility on the server machine to determine the status and port
number of the TimesTen Server. Generally, the TimesTen Server Daemon is
Working with the TimesTen Client and Server 71
started at installation time. If the TimesTen Server Daemon is not running, you
must start it. For information on starting the TimesTen Server, see “Modifying
the TimesTen Server daemon options” on page 84.
4.
Verify that the Client application can connect to the data store. If you cannot
establish a connection to the data store, check that the TTCONNECT.INI file
contains the correct information.
5.
If the information in the TTCONNECT.INI file is correct, check that a Server
DSN corresponding to the data store has been defined properly in the system
ODBC.INI file on the machine where the data store resides and where the
TimesTen Server Daemon is running.
72 Oracle TimesTen In-Memory Database Operations Guide
Troubleshooting Client/Server problems
This section includes the following topics:
• Cannot connect to theTimesTen Server
• TimesTen Server failed
• Cannot find TimesTen Server DSN
• TimesTen Server failed to load DRIVER
• Application times out when accessing TimesTen Server
• TimesTen Client loses connection with TimesTen Server
• Failed to attach to shared memory segment for IPC
• Increasing the maximum Server connections on Windows XP
Cannot connect to theTimesTen Server
You have not correctly identified the system where the TimesTen Server is
running.
On a Windows client machine, you select the TimesTen Server in the TimesTen
Data Source Setup dialog that is displayed as part of the ODBC Data Source
Administrator. To verify the TimesTen Server:
1.
On the Windows Desktop, choose Start > Settings > Control Panel.
2.
Double click the ODBC icon. This opens the ODBC Data Source Administrator.
3.
Click the System DSN tab. This displays the System Data Sources list.
4.
Select the TimesTen Client data source. This opens the TimesTen Client DSN
Setup dialog.
5.
Click Servers. This opens the TimesTen Logical Server List.
6.
Select the TimesTen Server from the list. This opens the TimesTen Logical
Server Name Setup dialog.
7.
Verify that the values for the Network Address and Port Number are correct. If
necessary, change the values.
Note: If you typed the hostname or network address directly into the Server
Name field of the TimesTen Client DSN Setup, the Client tries to connect to the
TimesTen Server using the default port.
If the Network Address and Port Number values are correct, the TimesTen Server
may not be running. See “Starting and stopping the Oracle TimesTen Data
Manager Service on Windows” on page 78 for information about starting the
server manually. See “Testing connections” on page 65 for more information on
identifying this problem.
Working with the TimesTen Client and Server 73
On UNIX, specify the TimesTen Server with the TTC_Server connection
attribute in the ODBC.INI file on the client machine. If the value specified for
TTC_Server is an actual hostname or IP address, the client tries to connect to the
TimesTen Server using the default port. In TimesTen, the default port is
associated with the TimesTen release number. If the value specified for
TTC_Server is a logical ServerName, this logical ServerName must be defined
in the TTCONNECT.INI file. The TTCONNECT.INI entry for this ServerName
needs to correctly define the hostname/IP address and port number on which the
TimesTen Server is listening.
If the Network Address and Port Number values are correct, the TimesTen
Server may not be running or did not start. See “Starting and stopping the
daemon on UNIX” on page 79 for information about starting the server manually.
See “Testing connections” on page 65 for more information on identifying this
problem.
TimesTen Server failed
Check the server's log file. On Windows, server log messages are stored in the
Application Log of the Event Viewer. On UNIX, server log messages are stored
in syslog. See “Creating and configuring Client DSNs on UNIX” on page 67.”
The maximum number of concurrent IPC connections to a TimesTen Server
allowed by TimesTen is 9,999. However, system limits can take precedence on
the number of connections to a single DSN. Client/Server users can change the
file descriptor limit to support a large number of connections. For an example,
see “Installation prerequisites” in the Oracle TimesTen In-Memory Database
Installation Guide.
Cannot find TimesTen Server DSN
On UNIX, verify that the Server DSN is defined in the SYS.ODBC.INI file on
the machine running the TimesTen Server.
On Windows, verify that the Server DSN is defined as a System DSN in the
ODBC Data Source Administrator on the machine running the TimesTen Server.
See “Creating and configuring a logical server name” on page 59.”
TimesTen Server failed to load DRIVER
This error only occurs on UNIX platforms. Open the SYS.ODBC.INI file on the
machine running the TimesTen Server and locate the Server DSN you are trying
to connect. Verify that the dynamic library specified in the DRIVER attribute for
the Server DSN exists and is executable.
Application times out when accessing TimesTen Server
The default TimeOut interval is 60 seconds.
74 Oracle TimesTen In-Memory Database Operations Guide
To increase this interval on UNIX, change the value of the TTC_Timeout
attribute in the ODBC.INI file.
To set the timeout interval on Windows, see the instructions in “Setting the
timeout interval and authentication” on page 62.
TimesTen Client loses connection with TimesTen Server
Check to see if the error was due to the Client timing out. Check the TimesTen
Server's log to see why the Server may have severed connection with the Client.
Use ping to determine if your network is up or try using telnet to connect to the
TimesTen Server port number.
Failed to attach to shared memory segment for IPC
While using shared memory segment (SHM) as IPC, the application may see the
following error message from the TimesTen Client ODBC Driver if the
application reaches the system-defined per-process file-descriptor-limit.
SQLState
= S1000,
Native Error = 0,
Message
= [TimesTen][TimesTen 6.0 CLIENT]Falied to
attach to shared memory segment for IPC. System error: 24
This may happen during a connect operation to the Client DSN when the shmat
system call fails because the application has more open file descriptors than the
system-defined per-process file descriptor limit. To correct this problem, you
must increase your system-defined per-process file descriptor limit. For
additional information on file descriptor limits, see Chapter 8, “System Limits,”
in the Oracle TimesTen In-Memory Database API and SQL Reference Guide.
Increasing the maximum Server connections on
Windows XP
On Windows XP, by default, there can be no more than 47 simultaneous
connections to the TimesTen Server. To avoid this limitation:
1.
From the Start > Programs > Administrative Tools > Services menu, select
TimesTen Data Manager release.
2.
On the LogOn tab, check the Allow service to interact with desktop checkbox
and click OK.
3.
Restart TimesTen Data Manager release
Working with the TimesTen Client and Server 75
76 Oracle TimesTen In-Memory Database Operations Guide
4
Working with the Oracle TimesTen
Data Manager Daemon
The Oracle TimesTen Data Manager daemon (Oracle TimesTen Data Manager
service on Windows) is a process that runs at a high level of privilege. It starts
automatically when TimesTen is installed by the root user and each time the
operating system is booted. The daemon operates continually in the background.
The TimesTen daemon performs the following functions:
• Manages shared memory access.
• Coordinates recovery.
• Keeps management statistics on what data stores exist, which are in use, and
which application processes are active.
• Coordinates deadlock detection.
• Manages RAM policy.
• Starts replication processes.
• Starts the TimesTen Server daemon
Application developers do not interact with the daemon directly. No application
code runs in the daemon and application developers do not generally have to be
concerned with it. Application programs that access TimesTen data stores
communicate with the daemon transparently using TimesTen internal routines.
This chapter discusses interaction with the TimesTen daemon on various
platforms. It includes the following topics:
• Starting and stopping the Oracle TimesTen Data Manager Service on
Windows
• Starting and stopping the daemon on UNIX
• Managing TimesTen daemon options
• Managing TimesTen Client/Server daemon options
• Modifying the TimesTen web server options
75
Starting and stopping the Oracle TimesTen Data Manager
Service on Windows
The Oracle TimesTen Data Manager service starts automatically when you install
the Oracle TimesTen Data Manager on your Windows system. To manually start
and stop the Oracle TimesTen Data Manager service, you can use the
ttDaemonAdmin utility with the -start or -stop option, or you can use the
Windows ODBC Data Source Administrator as follows:
1.
Open the ODBC Data Source Administrator:
On the Windows NT Desktop, choose Start > Settings > Control Panel
On Windows 2000 and XP, choose Start > Settings >Control Panel>
Administrator Tools
2.
Double-click Services. All currently available services are displayed.
3.
Select Oracle TimesTen Data Manager 6.0, then click the appropriate button to
stop or start the service.
Note: You must have administrative privileges to start and stop the TimesTen
service.
76 Oracle TimesTen In-Memory Database Operations Guide
Starting and stopping the daemon on UNIX
You must be root or the instance administrator to start and stop the TimesTen
daemon.
For root installations, the TimesTen main daemon starts automatically when
TimesTen is installed and each time the operating system is booted. The daemon
operates continually in the background.
For nonroot installations, the instance administrator must manually start and stop
the daemon unless the setuproot script has been run.
To manually start and stop the TimesTen main daemon, you can use the
ttDaemonAdmin utility with the -start or -stop option, or you can use the
TimesTen main daemon startup script for your platform.
The following table shows the location of the TimesTen main daemon startup
script by platform. These scripts exist only if the installation was root or if the
setuproot script has been run in a nonroot installation.
Solaris
# /etc/init.d/tt_TTinstance start
HP-UX
# /sbin/init.d/tt_TTinstance start
Linux
# /etc/rc.d/init.d/tt_TTinstance start
AIX
# startsrc -s tt_TTinstance
Tru64
# /sbin/init.d/tt_TTinstance start
To use the main daemon startup script to stop the daemon, enter:
Solaris
# /etc/init.d/tt_TTinstance stop
HP-UX
# /sbin/init.d/tt_TTinstance stop
Linux
# /etc/rc.d/init.d/tt_TTinstance stop
AIX
# stopsrc -s tt_TTinstance
Tru64
# /sbin/init.d/tt_TTinstance stop
On an AIX system with a root installation, you can also determine the status of
the daemon at any time by entering the command:
# lssrc -s TTinstance
Working with the TimesTen Data Manager Daemon 77
Managing TimesTen daemon options
The ttendaemon.options file allows you to set and modify TimesTen daemon
options. During installation, the installer sets some of these options to correspond
to your responses to the installation prompts. The features that the
ttendaemon.options file controls are:
• The addresses on which the daemon listens
• The verbosity of informational messages
• The minimum and maximum number of TimesTen subdaemons that can exist
for the TimesTen instance
• Whether or not the TimesTen Server daemon runs on your system
• Whether you use shared memory segments for client/server inter-process
communication
• The number of Server processes that are prespawned on your system
On Windows, the ttendaemon.options file is located in the directory:
install_dir\srv\info
On UNIX, the ttendaemon.options file is located in the directory:
/var/TimesTen/TTinstance/ (For root installations)
install_dir/info/ (For nonroot installations)
Note: To make most changes to the ttendaemon.options file, you must first
stop the TimesTen daemon and restart it after you have completed your changes.
For TimesTen Server options, it is only necessary to stop the server. It is not
necessary to stop the TimesTen daemon.
The rest of this section includes the following topics:
• Determining the daemon listening address
• Informational messages
• Changing the allowable number of subdaemons
• Diskless operations
Determining the daemon listening address
By default, the TimesTen main daemon, all subdaemons and agents listen on a
socket for requests, using any available address. All TimesTen utilities and
agents use the loopback address to talk to the main daemon, and the main
daemon uses the loopback address to talk to agents.
The -listenaddr entry in a separate line in the ttendaemon.options file tells
the TimesTen daemons to listen on the specific address indicated in the value
supplied. The address specified with this option can be either a host name or a
numerical IP address.
76 Oracle TimesTen In-Memory Database Operations Guide
To explicitly specify the address on which the daemons should listen on a
separate line in the ttendaemon.options file, enter:
-listenaddr address
For example, if you want to restrict the daemon to listen to just the loopback
address, you say either:
-listenaddr 127.0.0.1
or
-listenaddr localhost
This means that only processes on the local machine can communicate with the
daemon. Processes from other machines would be excluded, so you would not be
able to replicate to or from other machines, or grant client access from other
machines.
If you have multiple ethernet cards on different subnets, you can specify
-listenaddr entries to control which machines can connect to the daemon.
You can enter up to four addresses on which to listen by specifying the option
and a value on up to four separate lines in the ttendaemon.options file. In
addition to the addresses you specify, the loopback address is always listened on.
Informational messages
As the daemon operates, it generates error, warning and informational messages.
These messages may be useful for TimesTen system administration and for
debugging applications.
Modifying the informational message options on Windows
On Windows, the TimesTen Service (daemon) messages are logged in the Event
Viewer.
To turn off detailed log messages, add a ‘#’ before the -verbose to comment it
out in the ttendaemon.options file.
To log daemon messages to a user-specified file instead of sending them to
syslog, add the following on a separate line of the ttendaemon.options file:
-f filename
To view log messages, follow these steps:
1.
Open the Event Viewer window on your Windows Desktop.
2.
From the Log menu, choose Application.
The window changes to display only log messages generated by applications.
Any messages with the word “TimesTen” in the “Source” column were generated
by the Oracle TimesTen Data Manager service.
3.
To view any TimesTen message, double-click the message summary.
Working with the TimesTen Data Manager Daemon 77
The message window is displayed. You can view additional messages by clicking
Next / Previous or the up / down arrows, depending on your version of
Windows.
Note: You can also view messages using the ttDaemonLog utility.
Modifying the informational message options on UNIX
On UNIX systems, daemon messages are routed in a variety of ways, including
recording them to a file. These files can grow to be quite large. You should prune
them periodically to conserve disk space.
To specify the syslog facility used to log TimesTen Daemon and subdaemon
messages, on a separate line of the ttendaemon.options file add:
-facility name
Possible name values are: auth, cron, daemon, local0-local7, lpr, mail, news,
user, or uucp.
To turn off detailed log messages, add a “#” before the -verbose in the
ttendaemon.options file to comment it out.
To log daemon messages to a user-specified file instead of sending them to
syslog, on a separate line of the ttendaemon.options file add:
-f filename
When logging messages to a file, to additionally prepend the date to the message,
add the following on a separate line of the ttendaemon.options file:
-showdate
Changing the allowable number of subdaemons
TimesTen uses subdaemons to manage data stores. The main TimesTen daemon
spawns subdaemons dynamically as they are needed. You can manually specify a
range of subdaemons that the daemon may spawn, by specifying a minimum and
maximum.
At any point in time, one subdaemon is potentially needed for TimesTen process
recovery for each failed application process that is being recovered at that time.
By default, the maximum number of subdaemons is 50.
By default, TimesTen spawns a minimum of 4 subdaemons. However, you can
change these settings by assigning new values to the -minsubs and -maxsubs
options in the ttendaemon.options file.
Diskless operations
TimesTen allows you to work in diskless mode on UNIX systems. In diskless
mode the daemon does not use any disk files for its own purposes. In diskless
76 Oracle TimesTen In-Memory Database Operations Guide
mode you can only work with temporary data stores. To set diskless mode, you
must add the -diskless option to the ttendaemon.options file.
1.
If it does not already exist, create the ttendaemon.options file.
2.
In this file, put a line consisting of the string -diskless.
3.
Stop and restart the daemon.
Working with the TimesTen Data Manager Daemon 77
Managing TimesTen Client/Server daemon options
This section includes the following topics:
• Modifying the TimesTen Server daemon options
• Controlling the TimesTen Server daemon
• Prespawning TimesTen Server processes
• Using shared memory for Client/Server IPC
• Controlling the TimesTen Server log messages
Modifying the TimesTen Server daemon options
The TimesTen Server is a subdaemon of the TimesTen daemon that operates
continually in the background. To modify the TimesTen Server daemon options,
you must:
1.
Stop the TimesTen Server
2.
Modify the options in the ttendaemon.options file as described in the
following sections
3.
Restart the TimesTen Server.
Controlling the TimesTen Server daemon
The -server portno entry in a separate line in the ttendaemon.options file
tells the TimesTen daemon to start the TimesTen Server daemon and what port to
use. The portno is the port number on which the server will listen.
If the TimesTen Server is installed, you can enable or disable the TimesTen
Server daemon by:
• To enable the Server daemon, remove the comment symbol ‘#’ in front of the
-server portno entry.
• To disable the Server daemon, add a comment symbol ‘#’ in front of the
-server portno entry.
Prespawning TimesTen Server processes
Each TimesTen Client connection requires one server process. By default, a
server process is spawned when a client requests a connection.
You can prespawn a pool of server processes, making them immediately
available for a client connection, thus improving client/server connection
performance.
The -serverpool number entry in a separate line in the ttendaemon.options
file on the Server machine tells the TimesTen Server daemon create number
processes. If this option is not specified, 0 processes are pre-spawned.
76 Oracle TimesTen In-Memory Database Operations Guide
If you request more process than allowed by your operating system, a warning is
returned. Regardless of the number of processes requested, an error does not
occur unless a client requests a connection when no more are available on the
system. If there are no items in the server pool, a new process is spawned when a
connection is requested, as long as you have not met the operating system limit.
Note: This option is available for all systems, except Linux RedHat 8 systems.
These changes to the TimesTen Server daemon do not occur until the TimesTen
daemon is restarted.
Using shared memory for Client/Server IPC
By default, TimesTen uses TCP/IP communication between applications linked
with the TimesTen Client driver and the TimesTen Server.
Where the client application resides on the same machine as the TimesTen
Server, you can alternatively use shared memory for the inter-process
communication (IPC).
This can be useful for performance purposes or to allow 32-bit client applications
to communicate with a 64-bit data store on the server. Before using shared
memory as IPC verify that you have configured your system correctly. See
"Installation prerequisites" in Chapter 2 of the Oracle TimesTen In-Memory
Database Installation Guide.
The -serverShmIpc entry in a separate line in the ttendaemon.options file
tells the TimesTen Server daemon to accept a client connection that intends to
use a shared memory segment for IPC.
If this entry is missing, add this line to the ttendaemon.options file to start the
TimesTen Server daemon with shared memory IPC capability when the
TimesTen daemon is restarted.
If the entry exists, add the # symbol before the line in the ttendaemon.options
file to comment it out. The TimesTen Server is no longer started with shared
memory IPC capability when the TimesTen daemon starts.
Note: TimesTen supports a maximum of 16 different instances of the shared
memory IPC-enabled server. If an application tries to connect to more than 16
different shared memory segments it receives an ODBC error.
Managing the size of the shared memory segment
The -serverShmSize size entry in a separate line in the ttendaemon.options
file tells the TimesTen Server daemon to create a shared memory segment of the
specified size in MB.
Working with the TimesTen Data Manager Daemon 77
If this entry is missing, the TimesTen Server daemon creates a shared memory
segment of 64MB.
An appropriate value for the shared memory segment depends on:
• The expected number of concurrent client/server connections to all data stores
that belong to an instance of the TimesTen Server.
• The number of concurrent allocated statements within each such connection.
• The amount of data being transmitted for a query.
Some guidelines for determining the size of the shared memory segment include:
• TimesTen needs 1 MB of memory for internal use.
• Each connection needs a fixed block of 16 KB.
• Each statement starts with a block of 16 KB for the IPC. But, this size is
increased or decreased depending upon the size of the data being transmitted
for a query. TimesTen increments the statement buffer size by doubling it and
decreases it by halving it.
For example, if the user application anticipates a max of 100 simultaneous
shared-memory-enabled client/server connections, and if each connection is
anticipated to have a maximum of 50 statements, and the largest query returns
128 KB of data, use this formula to configure the serverShmSize:
serverShmSize = 1 MB + (100 * 16) KB + (100 * 50 * 128) KB
= 1 MB + 2 MB + 625 MB = 628 MB
This is the most memory required for this example. The entire memory segment
would be used only if all 100 connections have 50 statements each and each
statement has a query that returns 128 KB of data in a row of the result.
In this example, if you configured the serverShmSize to 128 MB, either a new
shared-memory-enabled client/server connection is refused by the TimesTen
Server or a query may fail due to lack of resources within the shared memory
segment.
Changing the size of the shared memory segment
Once configured, to change the value of the shared memory segment you must
stop the TimesTen Server. Stopping the server detaches all existing client/server
connections to any data store that is associated with that instance of the
TimesTen Server. The steps for modifying the value of the -serverShmSize
option are:
1.
Use the ttDaemonAdmin utility to stop the TimesTen Server.
2.
Modify the value of -serverShmSize in the ttendaemon.options file.
3.
Use the ttDaemonAdmin utility to restart the TimesTen Server.
76 Oracle TimesTen In-Memory Database Operations Guide
Controlling the TimesTen Server log messages
The -noserverlog entry in a separate line in the ttendaemon.options file tells
the TimesTen daemon to turn off logging of connects and disconnects from the
client applications.
If the TimesTen Server is installed, you can enable or disable logging of connect
and disconnect messages by:
• To enable logging, add a comment symbol ‘#’ before the -noserverlog entry.
• To disable logging, remove the comment symbol ‘#’ before the -noserverlog
entry.
Working with the TimesTen Data Manager Daemon 77
Modifying the TimesTen web server options
The TimesTen web server is a subdaemon of the TimesTen daemon that operates
continually in the background. The TimesTen web server allows users to use the
Cache Administrator, a web-based interface that allows you to work with cache
groups. For more information on cache groups, see the TimesTen Cache Connect
to Oracle Guide. If the TimesTen web server is specified in the
ttendaemon.options file, then the TimesTen web server starts and stops with
the TimesTen daemon.
To change whether the TimesTen web server is started by the daemon, perform
the following tasks:
1.
Stop the TimesTen daemon.
2.
Modify the ttendaemon.options file as described in "Controlling the TimesTen
web server".
3.
Restart the TimesTen daemon.
Controlling the TimesTen web server
The existence of a -webserver entry in a separate line in the
ttendaemon.options file tells the TimesTen daemon to start the TimesTen web
server.
If the TimesTen web server is installed, you can enable or disable the TimesTen
web server by:
• To start the web server, remove the comment symbol ‘#’ in front of the
-webserver entry.
• To stop the web server, add a comment symbol ‘#’ in front of the -webserver
entry.
Note: These changes do not take effect until the TimesTen daemon is restarted.
You can also start and stop the web server by using the ttDaemonAdmin utility.
76 Oracle TimesTen In-Memory Database Operations Guide
5
Using the ttIsql Utility
The TimesTen ttIsql utility is a general tool for working with a TimesTen data
source. The ttIsql command line interface is used to execute SQL statements and
built-in ttIsql commands to perform various operations. Some common tasks
that are typically accomplished using ttIsql include:
• Data store setup and maintenance. Creating tables and indexes, altering
existing tables and updating table statistics can be performed quickly and
easily using ttIsql.
• Retrieval of information on data store structures. The definitions for tables,
indexes and cache groups can be retrieved using built-in ttIsql commands. In
addition, the current size and state of the data store can be displayed.
• Optimizing data store operations. The ttIsql utility can be used to alter and
display query optimizer plans for the purpose of tuning SQL operations. The
time required to execute various ODBC function calls can also be displayed.
This chapter describes how the ttIsql utility is used to perform these types of
tasks. The topics are:
• Batch mode vs. interactive mode
• Using ttIsql’s online help
• Using ttIsql’s ‘editline’ feature (UNIX only)
• Using ttIsql’s command history
• Working with transactions
• Displaying data store information
• Viewing and changing query optimizer plans
• Timing ODBC function calls
• Working with prepared and parameterized SQL statements
• Defining default settings with the TTISQL environment variable
• Managing XLA bookmarks
• Handling Unicode characters
For more information on TimesTen SQL and for a detailed description of all
ttIsql commands see the Oracle TimesTen In-Memory Database API and SQL
Reference Guide.
89
Batch mode vs. interactive mode
The ttIsql utility can be used in two distinctly different ways: batch mode or
interactive mode. When ttIsql is used in interactive mode, users type commands
directly into ttIsql from the console. When ttIsql is used in batch mode, a
prepared script of ttIsql commands is executed by specifying the name of the file
containing the commands.
Batch mode is commonly used for the following types of tasks:
• Performing periodic maintenance operations including the updating of table
statistics, compacting the data store and purging log files.
• Initializing a data store by creating tables, indexes and cache groups and then
populating the tables with data.
• Generating simple reports by executing common queries.
Interactive mode is suited for the following types of tasks:
• Experimenting with TimesTen features, testing design alternatives and
improving query performance.
• Solving data store problems by examining data store statistics.
• Any other data store tasks that are not performed routinely.
By default, when starting ttIsql from the shell, ttIsql is in interactive mode. The
ttIsql utility prompts you to type in a valid ttIsql built-in command or SQL
statement by printing the Command> prompt.
Example 5.1
C:\>ttIsql
ttIsql (c) 1996-2005, Oracle. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.
All commands must end with a semicolon character.
Command>
All built-in ttIsql commands and SQL statements should be terminated with a
semicolon (;) character. The semicolon character tells ttIsql that the preceding
command is ready to be processed.
Batch mode can be accessed in two different ways. The most common way is to
specify the –f option on the ttIsql command line followed by the name of file to
run.
Example 5.2
For example, executing a file containing a CREATE TABLE statement will look
like this:
C:\>ttIsql -f create.sql MY_DSN
ttIsql (c) 1996-2005, Oracle.
All rights reserved.
90 Oracle TimesTen In-Memory Database Operations Guide
Type ? or "help" for help, type "exit" to quit ttIsql.
All commands must end with a semicolon character.
Command> connect "DSN=MY_DSN;Overwrite=1"
Connection successful: DSN=MY_DSN;DataStore=E:\ds\MY_DSN;
DRIVER=E:\WINNT\System32\TTdv60.dll;
(Default setting AutoCommit=1)
Command> run "create.sql"
CREATE TABLE LOOKUP (KEY INTEGER NOT NULL PRIMARY KEY, VALUE CHAR
(64))
Command> exit
Disconnecting...
Done.
C:\>
The other way to use batch mode is to enter the run command directly from the
interactive command prompt. The run command is followed by the name of the
file containing ttIsql built-in commands and SQL statements to execute.
Example 5.3
Command> run "create.sql";
CREATE TABLE LOOKUP (KEY INTEGER NOT NULL PRIMARY KEY, VALUE CHAR
(64))
Command>
Using the ttIsql Utility 91
Using ttIsql’s online help
The ttIsql utility has an online version of command syntax definitions and
descriptions for all built-in ttIsql commands. To access this online help from
within ttIsql use the help command. To view a detailed description of any builtin ttIsql commands type the help command followed by one or more ttIsql
commands to display help for. The example below displays the online description
for the connect and disconnect commands.
Example 5.4
Command> help connect disconnect;
All commands must end with a semicolon character.
Arguments in <> are required.
Arguments in [] are optional.
Command Usage: connect [DSN|connection_string]
Command Aliases: (none)
Description: Connects to the data source specified by the
optional DSN or
connection string argument. If an argument is not given, then the
DSN or
connection string from the last successful connection is used.
Requires an active connection: NO
Requires autocommit turned off: NO
Reports elapsed execution time: YES
Works only with a TimesTen data source: NO
Example: connect; -or- connect RunData; -or- connect
"DSN=RunData;Overwrite=1";
Command Usage: disconnect
Command Aliases: (none)
Description: Disconnects from the currently connected data
source. If a
transaction is active when disconnecting then the transaction
will be rolled
back automatically. If a connection exists when executing the
"bye", "quit" or
"exit" commands then the "disconnect" command will be executed
automatically.
Requires an active connection: YES
Requires autocommit turned off: NO
Reports elapsed execution time: YES
Works only with a TimesTen data source: NO
Example: disconnect;
Command>
92 Oracle TimesTen In-Memory Database Operations Guide
To view a short description of all ttIsql built-in commands type the help
command without an argument. To view a detailed description of all built-in
ttIsql commands type the help command followed by the all argument.
Using the ttIsql Utility 93
Using ttIsql’s ‘editline’ feature (UNIX only)
On UNIX systems, you can use the ‘editline’ library to set up emacs (default) or
vi bindings that enable you to scroll through previous ttIsql commands, as well
as edit and resubmit them. This feature is not available or needed on Windows.
The set up and keystroke information is described for each type of editor:
• Emacs binding
• vi binding
Emacs binding
To get the current settings, create a file ~/.editrc and put “bind” on the last line
of the file, run ttIsql. The editline lib will print the current bindings.
The keystrokes when using ttIsql with the emacs binding are:
Keystroke
Action
<Left-Arrow>
Move the insertion point left (back up)
<Right-Arrow>
Move the insertion point right (forward)
<Up-Arrow>
Scroll to the command prior to the one being
displayed. Places the cursor at the end of the line.
<Down-Arrow>
Scroll to a more recent command history item and
put the cursor at the end of the line.
<Ctrl-A>
Move the insertion point to the beginning of the line.
<Ctrl-E>
Move the insertion point to the end of the line.
<Ctrl-K>
“Kill” (Save and erase) the characters on the
command line from the current position to the end of
the line.
<Ctrl-Y>
“Yank” (Restore) the characters previously saved
and insert them at the current insertion point.
<Ctrl-F>
Forward char - move forward 1 (see Right Arrow)
<Ctrl-B>
Backward char - move back 1 (see Left Arrow)
<Ctrl-P>
Previous History (see Up Arrow)
<Ctrl-N>
Next History (see up Down Arrow)
94 Oracle TimesTen In-Memory Database Operations Guide
vi binding
To use the vi bindings, create a file ${HOME}/.editrc and put “bind-v” in the
file, run ttIsql. To get the current settings, create a file ${HOME}/.editrc and
put “bind” on the last line of the file. When you execute ttIsql, the editline lib
will print the current bindings.
The keystrokes when using ttIsql with the vi binding are:
Keystroke
Action
<Left-Arrow>, h
Move the insertion point left (back up)
<Right-Arrow>, l
Move the insertion point right (forward)
<Up-Arrow>, k
Scroll to the prior command in the history and put
the cursor at the end of the line.
<Down-Arrow>, j
Scroll to the next command in the history and put
the cursor at the end of the line.
ESC
Vi Command mode
0, $
Move the insertion point to the beginning of the line,
Move to end of the line.
i, I
Insert mode, Insert mode at beginning of the line
a, A
Add (“Insert after”) mode, Append at end of line
R
Replace mode
C
Change to end of line
B
Move to previous word
e
Move to end of word
<Ctrl-P>
Previous History (see Up Arrow)
<Ctrl-N>
Next History (see up Down Arrow)
Using the ttIsql Utility 95
Using ttIsql’s command history
The ttIsql utility stores a list of the last 100 commands executed within the
current ttIsql session. The commands in this list can be viewed or executed again
without having to type the entire command over. Both SQL statements and builtin ttIsql commands are stored in the history list. Use the history command (or h
for short) to view the list of previously executed commands.
Example 5.5
Command> h;
8
INSERT INTO T3 VALUES
9
INSERT INTO T1 VALUES
10
INSERT INTO T2 VALUES
11
INSERT INTO T3 VALUES
12
autocommit 0
13
showplan
14
SELECT * FROM T1, t2,
15
trytbllocks 0
16
tryserial 0
17
SELECT * FROM T1, t2,
Command>
(3)
(4)
(5)
(6)
t3 WHERE A=B AND B=C AND A=B
t3 WHERE A=B AND B=C AND A=B
The history command displays the last 10 SQL statements or ttIsql built-in
commands executed. To display more than that last 10 commands specify the
maximum number to display as an argument to the history command.
Each entry in the history list is identified by a unique number. The ! character
followed by the number of the command can be used to execute the command
again.
For example:
Example 5.6
Command>
Command> ! 12;
autocommit 0
Command>
To execute the last command again simply type a sequence of two !
characters.
Command> !!;
autocommit 0
Command>
96 Oracle TimesTen In-Memory Database Operations Guide
To execute the last command that begins with a given string type the ! character
followed by the first few letters of the command. For example:
Example 5.7
Command> ! auto;
autocommit 0
Command>
Using the ttIsql Utility 97
Working with transactions
The ttIsql utility has several built-in commands for managing transactions.
These commands are summarized below:
• autocommit – Turns on or off the autocommit feature.
• commit – Commits the current transaction.
• commitdurable – Commits the current transaction and ensures that the
committed work will be recovered in case of data store failure.
• rollback – Rolls back the current transaction.
• isolation – Changes the transaction isolation level.
• sqlquerytimeout – Specifies the number of seconds to wait for a SQL
statement to execute before returning to the application.
When starting ttIsql the autocommit feature is turned on by default. In this mode
every SQL operation against the data store is committed automatically. To turn
the autocommit feature off execute ttIsql’s built-in autocommit command with
an argument of 0.
When autocommit is turned off transactions must be committed or rolled back
manually by executing ttIsql’s commit, commitdurable or rollback commands.
The commitdurable command will ensure that the transaction’s effect is
preserved in case of data store failure.
The isolation command can be used to change the current connection’s
transaction isolation properties. The isolation can be changed only at the
beginning of a transaction. The isolation command accepts one of the
following constants: READ_COMMITTED and SERIALIZABLE. If the
isolation command is executed without an argument then the current isolation
level is reported.
The sqlquerytimeout command sets the timeout period for SQL statements. If
the execution time of a SQL statement exceeds the number of seconds set by
sqlquerytimeout, the SQL statement is not executed and an 6111 error is
generated. For details, see "Setting a timeout value for executing SQL
statements" in the Oracle TimesTen In-Memory Database Java Developer’s and
Reference Guide and "Setting a timeout value for executing SQL statements" in
the Oracle TimesTen In-Memory Database C Developer’s and Reference Guide.
The example below demonstrates the common use of ttIsql’s built-in transaction
management commands.
Example 5.8
E:\>ttIsql
ttIsql (c) 1996-2005, Oracle. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.
All commands must end with a semicolon character.
98 Oracle TimesTen In-Memory Database Operations Guide
Command> connect "DSN=MY_DSN";
Connection successful:
DSN=MY_DSN;DataStore=E:\ds\MY_DSN;DRIVER=E:\WINNT\System32\
TTdv60.dll;
(Default setting AutoCommit=1)
Command> autocommit 0;
Command> CREATE TABLE LOOKUP (KEY INTEGER NOT NULL PRIMARY KEY,
VALUE CHAR (64));
Command> commit;
Command> INSERT INTO LOOKUP VALUES (1, 'ABC');
1 row inserted.
Command> SELECT * FROM LOOKUP;
< 1,
ABC
>
1 row found.
Command> rollback;
Command> SELECT * FROM LOOKUP;
0 rows found.
Command> isolation;
isolation = READ_COMMITTED
Command> commitdurable;
Command> sqlquerytimeout 10;
Command> sqlquerytimeout;
Query timeout = 10 seconds
Command> disconnect;
Disconnecting...
Command> exit;
Done.
E:\>
Using the ttIsql Utility 99
Displaying data store information
There are several built-in ttIsql commands that display information on data store
structures. The most useful commands are summarized below:
• describe – Displays information on tables, prepared statements and
procedures.
• cachegroups – Displays the attributes of cache groups.
• dssize – Reports the current sizes of the permanent and temporary data store
partitions.
• monitor – Displays a summary of the current state of the data store.
The describe command is used to display information on table and result set
columns as well as parameters for prepared SQL statements and built-in
procedures. The argument to the describe command can be the name of a table,
a built-in procedure, a SQL statement or a command id for a previously prepared
SQL statement.
Example 5.9
Command> CREATE TABLE T1 (KEY INTEGER NOT NULL PRIMARY KEY, VALUE
CHAR (64));
Command> describe T1;
Table USER.T1:
Columns:
*KEY
VALUE
INTEGER NOT NULL
CHAR (64)
1 table found.
(primary key columns are indicated with *)
Command> describe SELECT * FROM T1 WHERE KEY=?;
Prepared Statement:
Parameters:
Parameter 1
Columns:
KEY
VALUE
Command> describe ttOptUseIndex;
Procedure TTOPTUSEINDEX:
Parameters:
Parameter INDOPTION
Columns:
(none)
INTEGER
INTEGER NOT NULL
CHAR (64)
VARCHAR (1024)
1 procedure found.
Command>
100 Oracle TimesTen In-Memory Database Operations Guide
The cachegroups command is used to provide detailed information on cache
groups defined in the current data store. The attributes of the root and child tables
defined in the cache group are displayed in addition to the WHERE clauses
associated with the cache group and the DURATION value for cache groups that
use cache aging. The argument to the cachegroups command is the name of the
cache group that you want to display information for.
Example 5.10
Command> cachegroups MY_CACHE_GROUP;
Cache Group USER.MY_CACHE_GROUP:
Duration: 40 Minutes
Root Table: USER.T1
Where Clause: (T1.KEY < 100)
Type: Not Propagate
Child Table: USER.T2
Where Clause: (none)
Type: Propagate
1 cache group found.
Command>
The dssize command is used to report the current memory status of the
permanent and temporary partitions as well as the maximum, allocated and inuse sizes for the data store. The monitor command displays all of the
information provided by the dssize command plus additional statistics on the
number of connections, checkpoints, lock timeouts, commits, rollbacks and other
information collected since the last time the data store was loaded into memory.
Example 5.11
Command> monitor;
TIME_OF_1ST_CONNECT:
DS_CONNECTS:
DS_DISCONNECTS:
DS_CHECKPOINTS:
DS_CHECKPOINTS_FUZZY:
DS_COMPACTS:
PERM_ALLOCATED_SIZE:
PERM_IN_USE_SIZE:
PERM_IN_USE_HIGH_WATER:
TEMP_ALLOCATED_SIZE:
TEMP_IN_USE_SIZE:
TEMP_IN_USE_HIGH_WATER:
SYS18:
XACT_BEGINS:
XACT_COMMITS:
Thu Sep 23 11:51:38 2005
4
0
2
0
0
204800
780
780
36864
2048
2048
0
16
15
Using the ttIsql Utility 101
XACT_D_COMMITS:
XACT_ROLLBACKS:
LOG_FORCES:
DEADLOCKS:
LOCK_TIMEOUTS:
LOCK_GRANTS_IMMED:
LOCK_GRANTS_WAIT:
CMD_PREPARES:
CMD_REPREPARES:
CMD_TEMP_INDEXES:
LAST_LOG_FILE:
REPHOLD_LOG_FILE:
REPHOLD_LOG_OFF:
REP_XACT_COUNT:
REP_CONFLICT_COUNT:
REP_PEER_CONNECTIONS:
REP_PEER_RETRIES:
FIRST_LOG_FILE:
LOG_BYTES_TO_LOG_BUFFER:
LOG_FS_READS:
LOG_FS_WRITES:
LOG_BUFFER_WAITS:
CHECKPOINT_BYTES_WRITTEN:
SYS1:
SYS2:
SYS3:
SYS4:
SYS5:
SYS6:
SYS7:
SYS8:
SYS10:
SYS11:
SYS12:
SYS13:
SYS14:
SYS15:
SYS16:
SYS17:
SYS19:
SYS9:
0
0
2
0
0
290
0
15
0
0
0
-1
-1
0
0
0
0
0
10960
0
2
0
1037176
0
0
0
0
0
0
23
0
0
0
0
0
0
0
0
0
0
Command>
102 Oracle TimesTen In-Memory Database Operations Guide
Viewing and changing query optimizer plans
The built-in showplan command is used to display the query optimizer plans
used by the TimesTen Data Manager for executing queries. In addition, ttIsql
contains built-in query optimizer hint commands for altering the query optimizer
plan. By using the showplan command in conjunction with the built-in
commands summarized below, the optimum execution plan can be designed. For
detailed information on the TimesTen query optimizer see Chapter 9 the Oracle
TimesTen In-Memory Database C Developer’s and Reference Guide.
• optprofile – Displays the current optimizer hint settings and join order.
• setjoinorder – Sets the join order.
• setuseindex – Sets the index hint.
• tryhash – Enables or disables the use of hash indexes.
• trymergejoin – Enables or disables merge joins.
• trynestedloopjoin – Enables or disables nested loop joins.
• tryserial – Enables or disables serial scans.
• trytmphash – Enables or disables the use of temporary hash indexes.
• trytmptable - Enables or disables the use of an intermediate results table.
• trytmpttree – Enables or disables the use of temporary ttree indexes.
• tryttree – Enables or disables the use of ttree indexes.
• tryrowid – Enables or disables the use of rowid scans.
• trytbllocks – Enables or disables the use of table locks.
• unsetjoinorder – Clears the join order.
• unsetuseindex – Clears the index hint.
When using the showplan command and the query optimizer hint commands the
auto-commit feature must be turned off. Use ttIsql’s autocommit built-in
command to turn auto-commit off.
The example below shows how these commands can be used to change the query
optimizer execution plan.
Example 5.12
Command> CREATE
Command> CREATE
Command> CREATE
Command>
Command> INSERT
1 row inserted.
Command> INSERT
1 row inserted.
Command> INSERT
1 row inserted.
Command> INSERT
1 row inserted.
TABLE T1 (A INTEGER);
TABLE T2 (B INTEGER);
TABLE T3 (C INTEGER);
INTO T1 VALUES (3);
INTO T2 VALUES (3);
INTO T3 VALUES (3);
INTO T1 VALUES (4);
Using the ttIsql Utility 103
Command> INSERT INTO T2 VALUES (5);
1 row inserted.
Command> INSERT INTO T3 VALUES (6);
1 row inserted.
Command>
Command> autocommit 0;
Command> showplan;
Command> SELECT * FROM T1, T2, T3 WHERE A=B AND B=C AND A=B;
Query Optimizer Plan:
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
1
3
TblLkSerialScan
T1
<NULL>
<NULL>
<NULL>
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
2
3
TblLkSerialScan
T2
<NULL>
<NULL>
T1.A = T2.B AND T1.A = T2.B
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
3
2
NestedLoop
<NULL>
<NULL>
<NULL>
<NULL>
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
4
2
TblLkSerialScan
T3
<NULL>
<NULL>
T2.B = T3.C
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
5
1
NestedLoop
<NULL>
<NULL>
<NULL>
104 Oracle TimesTen In-Memory Database Operations Guide
OTHERPRED:
<NULL>
< 3, 3, 3 >
1 row found.
Command> trytbllocks 0;
Command> tryserial 0;
Command> SELECT * FROM T1, t2, t3 WHERE A=B AND B=C AND A=B;
Query Optimizer Plan:
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
1
3
TmpTtreeScan
T1
<NULL>
<NULL>
<NULL>
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
2
3
TmpTtreeScan
T2
<NULL>
T2.B >= T1.A
<NULL>
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
3
2
MergeJoin
<NULL>
<NULL>
T1.A = T2.B AND T1.A = T2.B
<NULL>
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
4
2
TmpTtreeScan
T3
<NULL>
<NULL>
T2.B = T3.C
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
5
1
NestedLoop
<NULL>
<NULL>
<NULL>
Using the ttIsql Utility 105
OTHERPRED:
<NULL>
< 3, 3, 3 >
1 row found.
Command>
In this example a query against three tables is executed and the query optimizer
plan is displayed. The first version of the query simply uses the query optimizer’s
default execution plan. However, in the second version the trytbllocks and
tryserial built-in hint commands have been used to alter the query optimizer’s
plan. Instead of using serial scans and nested loop joins the second version of the
query uses temporary index scans and merge joins.
In this way the showplan command in conjunction with ttIsql’s built-in query
optimizer hint commands can be used to quickly determine which execution plan
should be used to meet application requirements.
106 Oracle TimesTen In-Memory Database Operations Guide
Timing ODBC function calls
Information on the time required to execute common ODBC function calls can be
displayed by using ttIsql’s timing command. When the timing feature is enabled
many built-in ttIsql commands will report the elapsed execution time associated
with the primary ODBC function call corresponding to the ttIsql command that
is executed.
For example, when executing ttIsql’s connect command several ODBC function
calls are executed, however, the primary ODBC function call associated with
connect is SQLDriverConnect and this is the function call that is timed and
reported as shown below.
Example 5.13
Command> timing 1;
Command> connect "DSN=MY_DSN";
Connection successful:
DSN=MY_DSN;DataStore=E:\ds\MY_DSN;DRIVER=E:\WINNT\System32\
TTdv60.dll;
(Default setting AutoCommit=1)
Execution time (SQLDriverConnect) = 1.2626 seconds.
Command>
In the example above, the SQLDriverConnect call took about 1.25 seconds to
execute.
When using the timing command to measure queries, the time required to
execute the query plus the time required to fetch the query results is measured. To
avoid measuring the time to format and print query results to the display, set the
verbosity level to 0 before executing the query.
Example 5.14
Command> timing 1;
Command> verbosity 0;
Command> SELECT * FROM T1;
Execution time (SQLExecute + FetchLoop) = 0.064210 seconds.
Command>
Using the ttIsql Utility 107
Working with prepared and parameterized SQL statements
Preparing a SQL statement just once and then executing it multiple times is much
more efficient for TimesTen applications than re-preparing the statement each
time it is to be executed. ttIsql has a set of built-in commands to work with
prepared SQL statements. These commands are summarized below:
• prepare – Prepares a SQL statement. Corresponds to a SQLPrepare ODBC
call.
• exec – Executes a previously prepared statement. Corresponds to a
SQLExecute ODBC call.
• execandfetch – Executes a previously prepared statement and fetches all
result rows. Corresponds to a SQLExecute call followed by one or more calls
to SQLFetch.
• fetchall – Fetches all result rows for a previously executed statement.
Corresponds to one or more SQLFetch calls.
• fetchone – Fetches only one row for a previously executed statement.
Corresponds to exactly one SQLFetch call.
• close – Closes the result set cursor on a previously executed statement that
generated a result set. Corresponds to a SQLFreeStmt call with the
SQL_CLOSE option.
• free – Closes a previously prepared statement. Corresponds to a
SQLFreeStmt call with the SQL_DROP option.
• describe – Describes the prepared statement including the input parameters
and the result columns.
The ttIsql utility prepared statement commands also handle SQL statement
parameter markers. When parameter markers are included in a prepared SQL
statement, ttIsql will automatically prompt for the value of each parameter in the
statement at execution time.
The example below uses ttIsql’s prepared statement commands to prepare an
INSERT statement into a table containing an INTEGER and a CHAR column.
The statement is prepared and then executed twice with different values for each
of the statement’s two parameters. ttIsql’s timing command is used to display
the elapsed time required to executed the primary ODBC function call associated
with each command.
Example 5.15
Command> connect "DSN=MY_DSN;Overwrite=1";
Connection successful:
DSN=MY_DSN;DataStore=E:\ds\MY_DSN;Overwrite=1;DRIVER=E:\WINNT\Sys
tem32\TTdv60.dll;
(Default setting AutoCommit=1)
Command> timing 1;
Command> CREATE TABLE T1 (KEY INTEGER NOT NULL PRIMARY KEY, VALUE
CHAR (64));
108 Oracle TimesTen In-Memory Database Operations Guide
Execution time (SQLExecDirect) = 0.1337 seconds.
Command> prepare INSERT INTO T1 VALUES (?,?);
Execution time (SQLPrepare) = 0.0668 seconds.
Command> exec;
All parameter values must be terminated with a semicolon
character.
Type '?;' for help on entering parameter values.
Type '*;' to abort the parameter entry process.
Enter Parameter 1 (INTEGER) >1;
Enter Parameter 2 (CHAR) >'abc';
1 row inserted.
Execution time (SQLExecute) = 0.0757 seconds.
Command> exec;
All parameter values must be terminated with a semicolon
character.
Type '?;' for help on entering parameter values.
Type '*;' to abort the parameter entry process.
Enter Parameter 1 (INTEGER) >2;
Enter Parameter 2 (CHAR) >'def';
1 row inserted.
Execution time (SQLExecute) = 0.0306 seconds.
Command> free;
Command> SELECT * FROM T1;
< 1,
abc
>
< 2,
def
>
2 rows found.
Execution time (SQLExecDirect) = 0.0316 seconds.
Command> disconnect;
Disconnecting...
Execution time (SQLDisconnect) = 1.7091 seconds.
Command>
Command>
In the example above, the prepare command is immediately followed by the
SQL statement to prepare. Whenever a SQL statement is prepared in ttIsql a
unique command ID is assigned to the prepared statement. ttIsql uses this ID to
keep track of multiple prepared statements. A maximum of 256 prepared
statements can exist in a ttIsql session simultaneously. When the free command
is executed, the command ID is automatically disassociated from the prepared
SQL statement.
Using the ttIsql Utility 109
To see the command IDs generated by ttIsql when using the prepared statement
commands, set the verbosity level to 4 using the verbosity command before
preparing the statement, or use the describe * command to list all prepared
statements with their IDs.
Command IDs can be referenced explicitly when using ttIsql’s prepared
statement commands. For a complete description of the syntax of ttIsql’s
prepared statement commands see the Oracle TimesTen In-Memory Database
API and SQL Reference Guide or type help at the ttIsql command prompt.
The example below prepares and executes a SELECT statement with a predicate
containing one INTEGER parameter. The fetchone command is used to fetch
the result row generated by the statement. The showplan command is used to
display the execution plan used by the TimesTen query optimizer when the
statement is executed. In addition, the verbosity level is set to 4 so that the
command ID used by ttIsql to keep track of the prepared statement is displayed.
Example 5.16
Command> connect "DSN=MY_DSN;Overwrite=1";
Connection successful:
DSN=MY_DSN;DataStore=E:\ds\MY_DSN;Overwrite=1;DRIVER=E:\WINNT\Sys
tem32\TTdv60.dll;
(Default setting AutoCommit=1)
The command succeeded.
Command> CREATE TABLE T1 (KEY INTEGER NOT NULL PRIMARY KEY, VALUE
CHAR (64));
The command succeeded.
Command> INSERT INTO T1 VALUES (1, 'abc');
1 row inserted.
The command succeeded.
Command> autocommit 0;
The command succeeded.
Command> showplan 1;
The command succeeded.
Command> verbosity 4;
The command succeeded.
Command> prepare SELECT * FROM T1 WHERE KEY=?;
Assigning new prepared command id = 0.
Query Optimizer Plan:
STEP:
LEVEL:
OPERATION:
TBLNAME:
IXNAME:
PRED:
OTHERPRED:
1
1
RowLkHashScan
T1
T1
T1.KEY = qmark_1
<NULL>
The command succeeded.
110 Oracle TimesTen In-Memory Database Operations Guide
Command> exec;
Executing prepared command id = 0.
All parameter values must be terminated with a semicolon
character.
Type '?;' for help on entering parameter values.
Type '*;' to abort the parameter entry process.
Enter Parameter 1 (INTEGER) >1;
The command succeeded.
Command> fetchone;
Fetching prepared command id = 0.
< 1,
abc
>
1 row found.
The command succeeded.
Command> close;
Closing prepared command id = 0.
The command succeeded.
Command> free;
Freeing prepared command id = 0.
The command succeeded.
Command> commit;
The command succeeded.
Command> disconnect;
Disconnecting...
The command succeeded.
Command>
Using the ttIsql Utility 111
Defining default settings with the TTISQL environment
variable
The ttIsql utility can be customized to automatically execute a set of command
line options every time a ttIsql session is started from the command prompt. This
is accomplished by setting an environment variable called TTISQL to the value
of the ttIsql command line that you prefer. A summary of ttIsql command line
options is shown below. For a complete description of ttIsql’s command line
options see the Oracle TimesTen In-Memory Database API and SQL Reference
Guide.
Example 5.17
Usage: ttIsql
[-h | -help | -helpcmds | -helpfull | -V]
[-connStr <connection_string>]
[-f <filename>]
[-v <verbosity>]
[-e <initialization_commands>]
[-interactive]
[-N <ncharencoding>]
[-wait]
The TTISQL environment variable has the same syntax requirements as the
ttIsql command line. When ttIsql starts up it reads the value of the TTISQL
environment variable and applies all options specified by the variable to the
current ttIsql session. If a particular command line option is specified in both the
TTISQL environment variable and the command line then the command line
version will always take precedence.
Example 5.18
The procedure for setting the value of an environment variable differs based on
the platform and shell that ttIsql is started from. As an example, setting the
TTISQL environment variable on Windows could look like this:
C:\>set TTISQL=-connStr "DSN=MY_DSN" -e "autocommit 0;tables;"
Example 5.19
In this example, ttIsql will automatically connect to a DSN called MY_DSN,
turn off autocommit and display all tables in the data store as shown below:
C:\>ttIsql
ttIsql (c) 1996-2005, Oracle. All rights reserved.
Type ? or "help" for help, type "exit" to quit ttIsql.
All commands must end with a semicolon character.
Command> connect "DSN=MY_DSN";
Connection successful:
DSN=MY_DSN;DataStore=E:\ds\MY_DSN;DRIVER=E:\WINNT\System32\TTdv60
.dll;
112 Oracle TimesTen In-Memory Database Operations Guide
(Default setting AutoCommit=1)
Command> autocommit 0;
Command> tables;
SYS.CACHE_GROUP
SYS.COLUMNS
SYS.COL_STATS
SYS.INDEXES
SYS.MONITOR
SYS.PLAN
SYS.SEQUENCES
SYS.TABLES
SYS.TBL_STATS
SYS.TRANSACTION_LOG_API
SYS.VIEWS
TTREP.REPELEMENTS
TTREP.REPLICATIONS
TTREP.REPPEERS
TTREP.REPSTORES
TTREP.REPSUBSCRIPTIONS
TTREP.REPTABLES
TTREP.TTSTORES
16 tables found.
Command>
Using the ttIsql Utility 113
Managing XLA bookmarks
You can use the xladeletebookmark command to both check the status of the
current XLA bookmarks and delete them. This command requires ADMIN
privilege or object ownership.
For example, when running the XLA application, ‘xlaSimple,’ you can check the
bookmark status by entering:
Command> xladeletebookmark;
XLA Bookmark: xlaSimple
Read Log File: 0
Read Offset:
630000
Purge Log File: 0
Purge Offset:
629960
PID:
2808
In Use:
No
1 bookmark found.
To delete the bookmark, enter:
Command> xladeletebookmark xlaSimple;
Command>
114 Oracle TimesTen In-Memory Database Operations Guide
Handling Unicode characters
TimesTen supports these national character set configurations:
• Japanese
• Korean
• Western European
By default, the ttIsql utility automatically detects the native OS locale settings
and processes data accordingly. In addition to the locale-based output, TimesTen
supports ASCII and UTF-8 output.
To override the locale-based output format, use the ncharencoding option or the
-N option. Setting ncharencoding to ASCII results in Unicode characters being
printed in escaped format. To set the output back to the locale-based setting, use
the ncharencoding LOCALE command. You do not need to have an active
connection to change the output method.
Note: This feature is not supported on Linux platforms.
Using the ttIsql Utility 115
116 Oracle TimesTen In-Memory Database Operations Guide
6
Working with Data in a TimesTen
Data Store
This chapter provides detailed information on the basic components in a
TimesTen data store and simple examples of how you can use SQL to manage
these components. For more information about SQL, see the Oracle TimesTen
In-Memory Database API and SQL Reference Guide.
For information on how to call SQL from within a C or Java application, see
“Managing TimesTen Data” in the Oracle TimesTen In-Memory Database Java
Developer’s and Reference Guide or “Managing TimesTen data” in the Oracle
TimesTen In-Memory Database C Developer’s and Reference Guide.
This chapter includes the following topics:
• Data store overview
• Understanding tables
• Working with tables
• Understanding materialized views
• Working with materialized views
• Understanding views
• Working with views
• Understanding indexes
• Working with indexes
• Understanding rows
• Working with rows
117
Data store overview
This section describes the main TimesTen data store elements and features. It
includes the following topics:
• Data store components
• Data store users and owners
• Data store persistence
Data store components
A TimesTen data store has the following permanent components:
• Tables. The primary components of a TimesTen data store are the tables that
contain the application data. See “Understanding tables” on page 120.
• Materialized Views. Read-only tables that hold a summary of data selected
from one or more “regular” TimesTen tables. See “Understanding
materialized views” on page 124.
• Views. Logical tables that are based on one or more tables called detail tables.
A view itself contains no data. See “Understanding views” on page 130.
• Indexes. Indexes on one or more columns of a table may be created for faster
access to tables. See “Understanding indexes” on page 133.
• Rows. Every table consists of 0 or more rows. A row is a formatted list of
values. See “Understanding rows” on page 136.
• System tables. System tables contain TimesTen metadata, such as a table of all
tables. See “System tables” on page 122 and the chapter “System and
Replication Tables” in the Oracle TimesTen In-Memory Database API and
SQL Reference Guide.
There are also many temporary components, including prepared commands,
cursors and locks.
Data store users and owners
Unless Access Control is enabled, the TimesTen Data Manager does not
authenticate user names. It accepts user names and ignores passwords entirely.
TimesTen Client/Server does authenticate users with passwords. Applications
should choose one UID for the application itself because by default the login
name that is being used to run the application becomes the owner of the data
store. If two different logins are used, TimesTen may have difficulty finding the
correct tables. If you omit the UID connection attribute in the connection string,
TimesTen uses the current user’s login name. TimesTen converts all user names
to upper case characters.
Users cannot access TimesTen data stores as user SYS. TimesTen determines the
user name by the value of the UID connection attribute, or if not present, then by
118 Oracle TimesTen In-Memory Database Operations Guide
the login name of the connected user. If a user’s login is SYS, set the UID
connection to override the login name.
Data store persistence
When a data store is created, it has either the permanent or temporary attribute
set:
• Permanent data stores are stored to disk automatically through a procedure
called checkpointing. TimesTen automatically performs background
checkpoints based on the settings of the data store attributes CkptFrequency
and CkptLogVolume. TimesTen also checkpoints the data store when the last
application disconnects. Applications can also checkpoint a data store directly
to disk by invoking the ttCkpt or ttCkptBlocking built-in procedures
described in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide.
• Temporary data stores are not stored to disk. A temporary data store is
automatically destroyed when no applications are connected to it. TimesTen
recommends either diskless logging or logging to disk to support transactions
and enable row-level locking. TimesTen removes any temporary disk-based
files, for example log files, when the last application disconnects. To delete
log files that are no longer needed, checkpoint operations should be used with
temporary data stores that use logging to disk.
Note: You cannot change the permanent or temporary attribute on a data store
after it is created.
Working with Data in a TimesTen Data Store 119
Understanding tables
A TimesTen table consists of rows that have a common format or structure. This
format is described by the table’s columns. Each column has:
• A data type
• Optional nullability, primary key and foreign key properties
• An optional default value
Unless you explicitly declare a column NOT NULL, columns are nullable. If a
column in a table is nullable, it can contain a NULL value. Otherwise, each row
in the table must have a non-NULL value in that column.
The format of TimesTen columns cannot be altered. It is possible to add or
remove columns but not to change column definitions. To add or remove
columns, use the ALTER TABLE statement. To change column definitions, an
application must first destroy the table and then recreate it with the new
definitions.
The rest of this section includes the following topics:
• In-line and out-of-line columns
• Default column values
• Table names
• Table access
• Primary keys, foreign keys and unique indexes
• System tables
In-line and out-of-line columns
The in-memory layout of the rows of a table is designed to provide fast access to
rows while minimizing wasted space. TimesTen designates each column of a
table as either in-line or not inline.
• An in-line column has a fixed length. All values of fixed-length columns of a
table are stored row wise.
• A not inline column has a varying length. Some VARCHAR, NVARCHAR or
VARBINARY data type columns are stored not inline. Not inline columns are
not stored contiguously with the row but are allocated. Accessing out-of-line
columns is slightly slower than accessing in-line columns. By default,
columns whose declared column length is > 128 bytes are stored out of line.
Columns whose declared column length is <= 128 bytes are stored inlined.
The maximum sizes of in-line and out-of-line portions of a row are listed in
“Estimating table size” on page 123.
120 Oracle TimesTen In-Memory Database Operations Guide
Default column values
When you create a table, you can specify default values for the columns. The
default value you specify must be compatible with the data type of the column.
You can specify one of the following default values for a column:
• NULL
• A constant value
• SYSDATE
• USER
• CURRENT_USER
• SYSTEM_USER
If you use the DEFAULT clause of the CREATE TABLE statement but do not
specify the default value, the default value is NULL. See “Column Definition” in
Oracle TimesTen In-Memory Database API and SQL Reference Guide.
Table names
A TimesTen table is identified uniquely by its owner name and table name. Every
table has an owner. By default, the owner is the user who created the table. Tables
created by TimesTen, such as system tables, have the owner name SYS, or TTREP
if created during replication.
To uniquely refer to a table, specify both its owner and name separated by a
period “.” (for example, MARY.PAYROLL). If an application does not specify an
owner, TimesTen looks for the table under the user name of the caller, then under
the user name SYS.
A name is an alphanumeric value that begins with a letter (not a digit). A name
can include underscores. The maximum length of a table name is 30 characters.
The maximum length of an owner name is also 30 characters. TimesTen displays
all table, column and owner names to upper case characters. See Chapter 10,
“Names” in the Oracle TimesTen In-Memory Database API and SQL Reference
Guide for additional information.
Table access
Applications access tables through SQL statements. The TimesTen query
optimizer automatically chooses a fast way to access tables. It uses existing
indexes or, if necessary, creates temporary indexes to speed up access. For
improved performance, applications should explicitly create indexes for
frequently searched columns because the automatic creation and destruction of
temporary indexes incurs a performance overhead. For more details, see “Tune
statements and use indexes” on page 168.
Working with Data in a TimesTen Data Store 121
Primary keys, foreign keys and unique indexes
The creator of a TimesTen table can designate one or more columns as a primary
key to indicate that duplicate values for that set of columns should be rejected.
Primary key columns cannot be nullable. A table can have at most one primary
key. TimesTen automatically creates a hash index on the primary key to enforce
uniqueness on the primary key and to guarantee fast access through the primary
key. Indexes are discussed in “Understanding indexes” on page 133. Once a row
is inserted, its primary key columns cannot be modified.
Primary key indexes use hashes. All other indexes use T-trees. Although a table
may have only one primary key, additional uniqueness properties may be added
to the table using unique indexes (see “CREATE INDEX” in the Oracle
TimesTen In-Memory Database API and SQL Reference Guide).
A primary key is optional and an application can achieve a similar effect by
creating a table with no primary key columns and then creating a unique index,
but it will create a t-tree.
Note: Columns of a primary key cannot be nullable; a unique index can be built
on nullable columns.
A table may also have one or more foreign keys through which rows correspond
to rows in another table. Foreign keys relate to a primary key in the other table.
Foreign keys use a T-tree index on the referencing columns (see “CREATE
TABLE” in the Oracle TimesTen In-Memory Database API and SQL Reference
Guide).
System tables
In addition to tables created by applications, a TimesTen data store contains
system tables. System tables contain TimesTen metadata such as descriptions of
all tables and indexes in the data store, as well as other information such as
optimizer plans. Applications may query system tables just as they query user
tables. Applications may not update system tables. TimesTen system tables are
described in the chapter “System and Replication Tables” in the Oracle
TimesTen In-Memory Database API and SQL Reference Guide.
Note: TimesTen system table formats may change between releases and are
different between the 32- and 64-bit versions of TimesTen.
122 Oracle TimesTen In-Memory Database Operations Guide
Working with tables
This section includes the following topics:
• Creating a table
• Destroying a table
• Estimating table size
Creating a table
To create a table, use the SQL statement CREATE TABLE. The syntax for all
SQL statements is provided in the Oracle TimesTen In-Memory Database API
and SQL Reference Guide. TimesTen converts table names to upper case
characters.
Example 6.1
The following SQL statement creates a table, called NameID, with two columns:
CustId and CustName. The table maps character names to integer identifiers.
CREATE TABLE NameID (CustId INTEGER, CustName VARCHAR(50));
This example creates a table, called Customer, with the columns: CustId,
CustName, Addr, Zip, and Region. The CustId column is designated as the
primary key, so that the CustId value in a row uniquely identifies that row in the
table, as described in “Primary keys, foreign keys and unique indexes” on page
122. The UNIQUE HASH ON (custId) PAGES value indicates that 30 buckets
are to be allocated for the table’s hash index.
CREATE TABLE Customer
(custId INT NOT NULL PRIMARY KEY,
custName CHAR(100) NOT NULL,
Addr CHAR(100),
Zip INT,
Region CHAR(10))
UNIQUE HASH ON (custId) PAGES = 30;
Destroying a table
To destroy a TimesTen table, call the SQL statement DROP TABLE.
Example 6.2
The following example drops the table NameID.
DROP TABLE NameID;
Estimating table size
Increasing the size of a TimesTen data store can be done on first connect or with
an exclusive connection. To avoid having to increase the size of a data store, it is
important not to underestimate the eventual data store size. Use the utility ttSize
to estimate data store size.
Working with Data in a TimesTen Data Store 123
Understanding materialized views
As described in Chapter 8, “Event Notification” of the Oracle TimesTen InMemory Database Architectural Overview, a materialized view is a read-only
table that maintains a summary of data selected from one or more “regular”
TimesTen tables. The summary data in a materialized view is called a result set
and the “regular” TimesTen tables queried to make up the result set are called
detail tables.
Figure 6.1
Materialized View
Application
Updates
Selects
Data Store
Materialized View
Detail Tables
124 Oracle TimesTen In-Memory Database Operations Guide
Working with materialized views
This section includes the following topics:
• Creating a materialized view
• Restrictions on materialized views and detail tables
• Performance implications of materialized views
• Destroying a materialized view
Creating a materialized view
To create a materialized view, use the SQL statement CREATE
MATERIALIZED VIEW. The syntax for all SQL statements is provided in the
Oracle TimesTen In-Memory Database API and SQL Reference Guide.
Assume the following two tables have been created:
CREATE TABLE customer(custId int not null,
custName char(100) not null,
Addr char(100),
Zip int,
Region char(10),
PRIMARY KEY (custId));
CREATE TABLE bookOrder(orderId int not null,
custId int not null,
ordNo int not null,
book char(100),
PRIMARY KEY (orderId),
FOREIGN KEY (custId) REFERENCES Customer(custId));
The following creates a materialized view, named SampleMV, that generates a
result set from selected columns in the customer and bookOrder detail tables
described above.
CREATE MATERIALIZED VIEW SampleMV AS
SELECT customer.custId, custName, ordNo, book
FROM customer, bookOrder
WHERE customer.custId=bookOrder.custId;
When creating a materialized view, you can establish primary keys and the size
of the hash table in the same manner as described for tables in “Primary keys,
foreign keys and unique indexes” on page 122.
The SELECT query in the CREATE MATERIALIZED VIEW statement
The SELECT query used to define the contents of a materialized view is similar
to the top-level SQL SELECT statement described in Chapter 13, “SQL
Statements” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide, with the following restrictions:
Working with Data in a TimesTen Data Store 125
• All columns in the GROUP BY GroupColumnList must be included in the
SelectList.
• Aggregate views must include a COUNT(*) in the SelectList so that TimesTen
can do incremental updates of a group. For example, a group should be
removed if its count becomes zero.
• SUM and COUNT are allowed, but not expressions involving them, including
AVG.
• The following clauses cannot be used in a materialized view SELECT query:
– DISTINCT
– FIRST
– HAVING
– ORDER BY
– FOR UPDATE
• Each expression in the SelectList must have a unique name. A name of a
simple column expression would be that column’s name unless a column alias
is defined. ROWID is considered an expression and needs an alias.
• OUTER JOINs are allowed, but the SelectList must project at least one nonnullable column from each of the inner tables specified in the OUTER JOIN.
Outer join syntax for a SELECT in a materialized view definition is identical
to that in a top-level SELECT. The restrictions noted in the description of
SELECT statements apply.
• Self joins are allowed. A self join is a join of a table to itself. This table
appears twice in the FROM clause and is followed by table aliases that qualify
column names in the join condition. Materialized views created with self-join
in this release of TimesTen will not work with any prior releases.
Restrictions on materialized views and detail tables
After a materialized view is created, changes made to the data in the detail tables
are immediately reflected in the materialized view. The only way to update a
materialized view is by changing the viewed data in the detail tables. A
materialized view is a read-only table that cannot be updated directly. This means
a materialized view cannot be updated by an INSERT, DELETE, or UPDATE
statement by replication, XLA, or the cache agent (it cannot be part of a cache
group).
For example, an attempt to update a row in a materialized view generates the
error:
805: Update view table directly has not been implemented
Readers familiar with other implementations of materialized views should note
the following characteristics of TimesTen views:
• Detail tables can be replicated, but materialized views cannot.
126 Oracle TimesTen In-Memory Database Operations Guide
• Neither a materialized view nor its detail tables can be part of a cache group.
• TimesTen does not automatically create indexes on materialized views or
detail tables. No referential indexes can be defined on the materialized view.
• A materialized view cannot be dropped with a DROP TABLE statement. You
must use the DROP VIEW statement.
• A materialized view cannot be altered with an ALTER TABLE statement.
You must use the DROP VIEW statement and then create a new materialized
view with a CREATE MATERIALIZED VIEW statement.
• Materialized views must be explicitly created by the application. The
TimesTen query optimizer has no facility to automatically create materialized
views.
• The TimesTen query optimizer does not rewrite queries on the detail tables to
reference materialized views. Application queries must directly reference
views, if they are to be used.
• There is no deferred maintenance option for materialized views. A
materialized view is refreshed automatically when changes are committed to
its detail tables and there is no facility for manually refreshing a view.
• There are some restrictions to the SQL used to create materialized views. See
CREATE MATERIALIZED VIEW in the Oracle TimesTen In-Memory
Database API and SQL Reference Guide for details.
Performance implications of materialized views
The performance of UPDATE, INSERT and CREATE VIEW operations may be
impacted if the updated table is referenced in a materialized view. The
performance impact depends on many factors, such as the nature of the view
(how many detail tables, whether outer join or aggregation is used), which
indexes are present on the detail table and on the view, and how many view rows
will be affected by the change.
A view is a persistent, up-to-date copy of a query result. To keep the view up to
date, TimesTen must do “view maintenance” when you change a view’s detail
table. For example, if you have a view named V that selects from tables T1, T2,
and T3, then any time you insert into T1, or update T2, or delete from T3,
TimesTen does “view maintenance.”
View maintenance needs appropriate indexes just like regular database
operations. If they're not there, view maintenance will take a very long time.
All of the updates/inserts/deletes on detail tables have execution plans, as
described in Chapter 9, “The TimesTen Query Optimizer.” For example, an
update of a row in T1 will have a first stage of the plan where it updates the view
V, followed by a second stage where it updates T1.
Working with Data in a TimesTen Data Store 127
For view maintenance to be fast, you should look at the plans for all the
operations that update (write to) the detail tables and make sure they look good.
This may be time-consuming, so here's an easy method to start off with:
1.
Look at all the WHERE clauses for the updates/deletes that frequently happen on
the detail tables. Those clauses will probably use an index key. Make a note of
each of those keys. For example, if the operations that an application does 95%
of the time are:
* update T1 set A=A+1 WHERE K1=? AND K2=?
* delete from T2 WHERE K3=?
Then the keys you're remembering are (K1,K2) and K3.
2.
Make sure that the view selects all of those key columns. In this example, the
view should select K1, K2, and K3.
3.
Create an index on the view on each of those keys. In this example, the view
should have two indexes, one on (V.K1,V.K2) and one on V.K3. The indexes
don't have to be unique, though they can be. (And the names of the view columns
can be different from the names of the table columns, though they're the same in
this example.)
With this method, when you update a detail table, your WHERE clause is used to
do the corresponding update of the view. This allows maintenance to be done in a
batch, and is very fast.
The above method may not always work, however. For example, an application
may have many different ways of updating the detail tables, and so would have to
select far too many things in the view, or create too many indexes on the view,
taking up more space or more performance than you might like. So, if the above
is too cumbersome, an alternative method is:
1.
For each table in the view's FROM clause (each detail table), check which ones
are frequently changed by UPDATE, INSERT, or CREATE VIEW statements.
For example, a view's FROM clause may have tables T1, T2, T3, T4, T5, but of
those, only T2 and T3 are frequently changed.
2.
For each of those tables, make sure the view selects their rowids. In this example,
the view should select T2.rowid and T3.rowid.
3.
Create an index on the view on each of those rowid columns. In this example, the
columns might be called T2rowid and T3rowid, and indexes would be created on
V.T2rowid and V.T3rowid.
With this method, view maintenance is done on a row-by-row basis, rather than
on a batch basis. But the rows can be matched very efficiently between a view
and its detail tables. So that speeds up the maintenance. It's generally not as fast
as the first method, but it's still pretty good.
128 Oracle TimesTen In-Memory Database Operations Guide
Destroying a materialized view
To destroy a materialized view, call the DROP VIEW SQL statement.
Example 6.3
The following statement drops the sampleMV materialized view, sampleMV.
DROP VIEW sampleMV;
Working with Data in a TimesTen Data Store 129
Understanding views
A view is a logical table that is based on one or more tables called detail tables.
The view itself contains no data. It is sometimes called a nonmaterialized view to
distinguish it from a materialized view, which does contain data that has already
been calculated from the detail tables. Views cannot be updated directly, but
changes to the data in the detail tables are immediately reflected in the view.
To choose whether to create a view or a materialized view, consider where the
cost of calculation lies. For a materialized view, the cost falls on the users who
update the detail tables because calculations must be made to update the data in
the materialized views. For a nonmaterialized view, the cost falls on a connection
that queries the view, because the calculations must be made at the time of the
query.
130 Oracle TimesTen In-Memory Database Operations Guide
Working with views
This section includes the following topics:
• Creating a view
• The SELECT query in the CREATE VIEW statement
• Restrictions on views and their detail tables
• Destroying a view
Creating a view
To create a view, use the CREATE VIEW SQL statement. The syntax for all SQL
statements is provided in the Oracle TimesTen In-Memory Database API and
SQL Reference Guide.
CREATE VIEW ViewName AS SelectQuery;
This selects columns from the detail tables to be used in the view. You can also
create indexes on the view.
For example, create a view from the table t1:
CREATE VIEW v1 AS SELECT * FROM t1;
Now create a view from an aggregate query on the table t1:
CREATE VIEW v1 (max1) AS SELECT max(x1) FROM t1;
The SELECT query in the CREATE VIEW statement
The SELECT query used to define the contents of a materialized view is similar
to the top-level SQL SELECT statement described in Chapter 13, “SQL
Statements” in the Oracle TimesTen In-Memory Database API and SQL
Reference Guide, with the following restrictions:
• A SELECT * query in a view definition is expanded at view creation time.
Any columns added after a view is created do not affect the view.
• The following cannot be used in a SELECT statement that is creating a view:
– DISTINCT
– FIRST
– ORDER BY
– UNION
– UNION ALL
– User functions: USER, CURRENT_USER and SYSTEM_USER
• Each expression in the select list must have a unique name. A name of a
simple column expression would be that column’s name unless a column alias
is defined. RowId is considered an expression and needs an alias.
• No SELECT FOR UPDATE or SELECT FOR INSERT statements can be
used on a view.
Working with Data in a TimesTen Data Store 131
• Certain TimesTen query restrictions are not checked when a non-materialized
view is created. Views that violate those restrictions may be allowed to be
created, but an error is returned when the view is referenced later in an
executed statement.
Restrictions on views and their detail tables
Views have the following restrictions:
• When a view is referenced in the FROM clause of a SELECT statement, its
name is replaced by its definition as a derived table at parsing time. If it is not
possible to merge all clauses of a view to the same clause in the original select
to form a legal query without the derived table, the content of this derived
table is materialized. For example, if both the view and the referencing select
specify aggregates, the view is materialized before its result can be joined
with other tables of the select.
• A view cannot be dropped with a DROP TABLE statement. You must use the
DROP VIEW statement.
• A view cannot be altered with an ALTER TABLE statement.
• Referencing a view can fail due to dropped or altered detail tables.
Destroying a view
The DROP VIEW statement deletes the specified view, including any hash
indexes and any T-tree indexes associated with it.
The following statement drops the CustOrder view:
DROP VIEW CustOrder;
132 Oracle TimesTen In-Memory Database Operations Guide
Understanding indexes
Indexes are auxiliary data structures that speed up table searches. They are used
automatically by the query optimizer to speed up the execution of a query. For
information about the query optimizer, see Chapter 9, “The TimesTen Query
Optimizer.”
TimesTen provides two types of indexes to enable faster access to tables: hash
indexes and T-tree (or range) indexes.
• Hash Indexes. Hash indexes are useful for finding rows with an exact match
on one or more columns. TimesTen currently supports a maximum of one
hash index per table. The hash index must be over the primary key of a table.
A hash index is created automatically when a table is created with a primary
key specified on one or more columns or with the UNIQUE HASH option
specified on one or more columns of the table.
The section “CREATE TABLE” of the Oracle TimesTen In-Memory
Database API and SQL Reference Guide discusses in detail the automatic
creation of hash indexes.
• T-tree Indexes. T-tree indexes are useful for finding rows with column values
within a certain range. They are also useful for finding rows with an exact
match on one or more columns. T-trees were designed specifically for inmemory applications. T-tree indexes may be created over one or more
columns of a table, and up to 32 T-tree indexes may be created on one table.
Hash indexes are useful only for doing equality searches, while T-trees and
equijoins can be used for equality and range (greater than/equal to, less than/
equal to, etc.) searches. So if you have a primary key on a field and want to see if
FIELD > 10, the primary key index will not expedite finding the answer, but a
separate index will.
Note: Hash indexes are faster than T-tree indexes for exact match lookups, but
they require more space than T-tree indexes. Hash indexes cannot be used for
lookups involving ranges.
You can designate an index as unique, which means that each row in the table has
a unique value for the indexed column or columns. Unique indexes can be
created over nullable columns. In conformance with the SQL standard, multiple
NULL values are permitted in a unique index.
When sorting data values, TimesTen considers NULL values to be larger than all
non-NULL values. See the Oracle TimesTen In-Memory Database API and SQL
Reference Guide for more information on NULL values.
In addition to hash and T-tree indexes, lookups by RowID can be used for fast
access to data. RowID lookups are faster than either type of index lookup. See
Working with Data in a TimesTen Data Store 133
the Oracle TimesTen In-Memory Database API and SQL Reference Guide for
more information on RowIDs.
134 Oracle TimesTen In-Memory Database Operations Guide
Working with indexes
This section includes the following topics:
• Creating an index
• Destroying an index
• Estimating index size
Creating an index
To create an index, call the SQL statement CREATE INDEX. TimesTen converts
index names to upper case characters.
Every index has an owner. The owner is the user who created the underlying
table. Indexes created by TimesTen itself, such as indexes on system tables, are
created with the user name SYS or with the user name TTREP if created during
replication.
Example 6.4
Create an index IxID over column CustID of table NameID.
CREATE INDEX IxID ON NameID (CustID);
Currently, it is not possible to create a hash index except by using the primary
key or hash clause in the table creation statement. However, TimesTen may
create temporary hash and T-tree indexes automatically during query processing
to speed up query execution.
Destroying an index
To uniquely refer to an index, an application must specify both its owner and
name. If the application does not specify an owner, TimesTen looks for the index
first under the user name of the caller, then under the user name SYS.
To destroy a TimesTen index, call the DROP INDEX SQL statement. All
indexes in a table are destroyed automatically when the table is destroyed.
Example 6.5
The following drops the index IxID.
DROP INDEX IxID;
Estimating index size
Increasing the size of a TimesTen data store can be done on first connect or with
an exclusive connection. To avoid having to increase the size of a data store, it is
important not to underestimate the eventual data store size. Use the utility ttSize
to estimate data store size.
Working with Data in a TimesTen Data Store 135
Understanding rows
Rows are used to store TimesTen data. TimesTen supports several data types for
fields in a row, including:
• One-byte, two-byte, four-byte and eight-byte integers.
• Four-byte and eight-byte floating-point numbers.
• Fixed-length and variable-length character strings, both ASCII and Unicode.
• Fixed-length and variable-length binary data.
• Fixed-length fixed-point numbers.
• Time represented as hh:mm:ss [AM|am|PM|pm].
• Date represented as yyyy-mm-dd.
• Timestamp represented as yyyy-mm-dd hh:mm:ss.
Chapter 9, “Data Types” in the Oracle TimesTen In-Memory Database API and
SQL Reference Guide contains a detailed description of these data types.
136 Oracle TimesTen In-Memory Database Operations Guide
Working with rows
This section includes the following topics:
• Inserting rows
• Deleting rows
Inserting rows
To insert a row, call INSERT or INSERT SELECT. You can also use the
ttBulkCp utility.
Example 6.6
To insert a row in the table NameID, enter
INSERT INTO NameID VALUES(23125, 'John Smith';
Note: When inserting multiple rows into a table, it is more efficient to use
prepared commands and parameters in your code. Bulk loads are fastest if done
with an exclusive connection (See “ExclAccess” in the Oracle TimesTen InMemory Database API and SQL Reference Guide) to the data store. Create
indexes after the bulk load is completed.
Deleting rows
To delete a row, call the DELETE statement.
Example 6.7
The following deletes all the rows from the table NameID for names that start with
the letter “S.”
DELETE FROM NameID WHERE CustName LIKE 'S%';
Working with Data in a TimesTen Data Store 137
138 Oracle TimesTen In-Memory Database Operations Guide
7
Transaction Management and
Recovery
TimesTen supports transactions that provide atomic, consistent, isolated and
durable (ACID) access to data.
TimesTen transactions support ANSI Serializable and ANSI Read_Committed
levels of isolation. ANSI Serializable isolation is the most stringent transaction
isolation level. ANSI Read_Committed allows greater concurrency.
Read_Committed is the default and is an appropriate isolation level for most
applications. These isolation levels can be combined with each other and with a
range of durability options.
TimesTen allows applications to choose the transaction features they need so
they do not incur the performance overhead of features they do not need. See
Chapter 1, “Data Store Attributes” in the Oracle TimesTen In-Memory Database
API and SQL Reference Guide for details on how to set isolation levels and
durability options.
The main topics in this chapter are:
• Transaction semantics
• Transaction atomicity and durability
• Controlling durability and logging
• Concurrency control
• Checkpoints
139
Transaction semantics
TimesTen maintains user-specified levels of isolation, atomicity and durability.
As a transaction modifies data in a data store, locking, versioning and logging are
used to ensure ACID properties:
• Locking. TimesTen acquires locks on data items that the transaction reads
and/or writes, depending on the transaction isolation level. See “Concurrency
control” on page 150.
• Logging. Modifications to the data store are recorded at user-specified levels
in a log. See “Transaction atomicity and durability” on page 143.
• Versioning. TimesTen makes multiple copies of data items to allow nonserializable read and write operations on those data items to proceed in
parallel.
The following table shows how TimesTen uses locks and logs:
If
Then
Transaction is terminated
successfully (committed)
• Log is posted to disk (if the DurableCommits
attribute is turned on).
• Newly modified values of data are made
available for other transactions to read and to
modify.
• Locks that were acquired on behalf of the
transaction are released and the corresponding
data becomes available to other transactions.
Transaction is rolled
back
• Log is used to undo the effects of the
transaction and to restore any modified data
items to the state they were before the
transaction began.
• Locks that were acquired on behalf of the
transaction are released and the corresponding
data becomes available to other transactions.
140 Oracle TimesTen In-Memory Database Operations Guide
If
Then
System fails (data not
committed)
• On first connect, TimesTen automatically
performs data store recovery by reading the
latest checkpoint image and applying the log to
restore the data store to its latest
transactionally consistent state. (See
“Checkpoints” on page 153).
Application fails
• Transaction is rolled back, if possible.
• If rollback is not possible, other connections to
data store may be invalidated.
• Recovery is done on next connect (See
“Recovery” on page 25.)
TimesTen supports temporary data stores, which have essentially no checkpoints.
Recovery is never done for such data stores. They will be destroyed after a data
store or application shuts down or fails.
TimesTen supports data stores with no logging. Rollback is not possible for such
data stores, and recovery uses only the latest checkpoint. This mode is suitable
only for special-purpose operations, such as bulk-loading a data store.
Transactions are started automatically on behalf of an application as needed.
Virtually all operations on the data store, even those that do not modify or access
application data, require transactional access. For example, compaction and
checkpoint operations begin a transaction if one has not already been started. An
application can commit a transaction by calling the ODBC SQLTransact (henv,
hdbc, SQL_COMMIT) function or JDBC Connection.commit method, or abort
it by calling the ODBC SQLTransact (henv, hdbc, SQL_ROLLBACK) function
or Connection.rollback method. Any subsequent data store operation will
automatically cause a new transaction to be started.
In compliance with ODBC standards, the default AUTOCOMMIT setting is ON.
Commits are costly for performance and can be intrusive if they are
implicit.TimesTen recommends that you turn AUTOCOMMIT off so that
commits are intentional. Use the ODBC SQLSetConnectOption function or
JDBC Connection.setAutoCommit(false) method in your TimesTen application
to set SQL_AUTOCOMMIT_OFF.
Transaction Management and Recovery 141
When using ODBC or JDBC batch operations to INSERT, UPDATE or
CREATE VIEW several rows in one call, when AUTOCOMMIT is on, a
commit occurs after the entire batch operation has completed. If there is an error
during the batch operation, those rows that have been successfully modified will
be committed. If an error occurs due to a problem on a particular row, the
preceding rows are committed. The pirow parameter to the ODBC
SQLParamOptions function contains the number of the row in the batch that
had the problem.
Even with durable commits and autocommit enabled, you could lose work if
there is a failure or the application exits without closing cursors. An open cursor
under AUTOCOMMIT means that you are in effect running with
AUTOCOMMIT off but without the ability to rollback. Write locks (from DDL
or DML) are held until all cursors are closed.
Note: Autocommit is the default mode for ODBC applications. Applications
must explicitly turn autocommit off to avoid it.
142 Oracle TimesTen In-Memory Database Operations Guide
Transaction atomicity and durability
The TimesTen Data Manager provides durability with a combination of
checkpointing and logging. (See “Checkpoints” on page 153 and “Log files” on
page 149.)
Because transaction support adds overhead to execution time, TimesTen allows
applications to choose from the following options:
• Guaranteed atomicity and durability. (Logging=1, DurableCommits=1)
• Guaranteed atomicity, delayed durability. (Logging=1, DurableCommits=0)
• Guaranteed atomicity, no guaranteed durability.
(Logging=2, DurableCommits=0)
• No guaranteed atomicity, no guaranteed durability.
(Logging=0, DurableCommits=0)
Overview
The following table summarizes the guarantees and limitations of the atomicity
and durability options:
Logging
Attribute
Setting
Nonblocking
checkpoints
possible?
Rowlevel
locking
possible
?
Transaction
rollback
possible?
Recovery
procedure
Transactions
vulnerable to
loss
Logging = 1
Durable
Commits = 1
Yes
Yes
Yes
Read most
recent
checkpoint
image.
Apply log.
Uncommitted
transactions at
the time of
failure
Logging = 1
Durable
Commits = 0
Yes
Yes
Yes
Read most
recent
checkpoint
image.
Apply log.
Transactions
that committed
after the last
checkpoint or
durable
commit
Transaction Management and Recovery 143
Logging
Attribute
Setting
Nonblocking
checkpoints
possible?
Rowlevel
locking
possible
?
Transaction
rollback
possible?
Recovery
procedure
Transactions
vulnerable to
loss
Logging = 2
Durable
Commits = 0
No
Yes
Yes
Read most
recent
checkpoint
image.
There is no
log to apply.
Transactions
that committed
after the last
checkpoint
Logging = 0
Durable
Commits = 0
No
No
No
Read most
recent
checkpoint
image.
There is no
log to apply.
Transactions
that committed
after the last
checkpoint
The sections that follow description these options in greater detail.
Guaranteed atomicity and durability
(Logging=1, DurableCommits=1)
By default, all TimesTen transactions are durable. The effects of the transaction
are persistent and will not be lost in the event of system failure.
Durability is implemented with a combination of checkpointing and logging.
(See “Checkpoints” on page 153 and “Log files” on page 149.) A checkpoint
operation writes the current data store image to a checkpoint file on disk, which
has the effect of making all transactions that committed before the checkpoint
durable. For transactions that committed after the last checkpoint, TimesTen uses
conventional logging techniques to make them durable. As each transaction
progresses, it records its data store modifications in an in-memory log. At
commit time, the relevant portion of the log is flushed to disk. This log flush
operation makes that transaction, and all previously-committed transactions,
durable.
In the case of a system failure, recovery uses the last checkpoint image together
with the log to reconstruct the latest transaction-consistent state of the data store.
In addition to being durable, by default all TimesTen transactions are also atomic.
Either all or none of the effects of the transaction is applied to the data store.
Atomicity is implemented by using the log to undo the effects of a transaction if
it is rolled back. Rollback can be caused explicitly by the application, using the
144 Oracle TimesTen In-Memory Database Operations Guide
ODBC SQLTransact function or JDBC Connection.rollback method, or during
data store recovery because the transaction was not committed at the time of
failure.
In order to have guaranteed atomicity and durability, applications must set the
Logging and DurableCommits attributes to 1, which is the default for each
attribute for permanent data stores.
Guaranteed atomicity, delayed durability
(Logging=1, DurableCommits=0)
It is possible to connect to a data store with logging enabled but with guaranteed
durability disabled. In this case, the atomicity of a transaction is guaranteed, but
not its durability. This mode is known as delayed durability mode.
In delayed durability mode, as in guaranteed durability mode, each transaction
enters records into the in-memory log as it makes modifications to the data store.
However, when a transaction commits in delayed durability mode, it does not
wait for the log to be posted to disk before returning control to the application.
Since the content of the in-memory log would be lost in a system failure,
transactions committed in this mode are not durable.
Non-durably committed transactions typically have better response time than
durably-committed transactions, because no I/O is required to commit the
transaction. A non-durably committed transaction can be made durable either by
checkpointing (See “Checkpoints” on page 153.) or by committing a subsequent
transaction durably. As with guaranteed durability mode, a checkpoint makes all
transactions that committed before the checkpoint durable. Committing a
transaction durably commits that transaction and all previously committed
transactions.
Applications that wish to take advantage of the performance benefits of delayed
durability mode but which can only tolerate the loss of a small number of
transactions can perform periodic durable commits in a background process —
only those transactions that committed non-durably after the last durable commit
are vulnerable to loss in the event of a system failure.
Applications request delayed durability mode by setting the Logging attribute to
1 (the default) and the DurableCommits attribute to 0. When in this mode,
applications can call the ttDurableCommit built-in procedure to force the
current transaction to commit durably when it commits.
Guaranteed atomicity, no guaranteed durability
(Logging=2, DurableCommits=0)
TimesTen's diskless logging mode can be used for applications needing even
greater performance than is offered by delayed durability mode (or which do not
Transaction Management and Recovery 145
have access to a disk), and which can tolerate even greater potential transaction
loss.
In diskless logging (no guaranteed durability) mode, the in-memory log is never
written to disk at all. It therefore cannot be used to ensure transaction durability
— its use in this mode is limited to enabling transaction atomicity through
transaction rollback. In no guaranteed durability mode, the only way to make a
transaction durable is by checkpointing the data store. (See “Checkpoints” on
page 153.)
In the event of a system failure, recovery reloads the data store from the last
checkpoint image, as in the other modes. However, since there are no on-disk
logs, the effects of any transactions that committed after the last checkpoint are
lost.
Diskless logging must be used with care as it has many limitations
• The in-memory log may grow to exhaust the size of its buffer if there are longrunning transactions
• Replication with diskless logging is restricted to temporary data stores
• Nonblocking checkpoints are not available, because recovery from
nonblocking checkpoints requires an on-disk log.
For these reasons, we recommend the use of disk logging over diskless logging
when possible.
To enable diskless logging mode, applications must set Logging=2. In addition,
they must set DurableCommits=0.
Note: Logging to disk is highly recommended when row-level locking is
enabled. (See “LockLevel.” and “Logging.” in the Oracle TimesTen In-Memory
Database API and SQL Reference Guide.) Diskless logging is provided for
systems without disks, or for systems with relatively slow disks where even an
occasional disk write has significant impact on performance. When diskless
logging is enabled, log records are stored only in the internal log buffer.
TimesTen does not write the log buffer to disk. If TimesTen runs out of space in
the internal log buffer while transactions are active, TimesTen forces transactions
that encounter a full log buffer to abort. An application that chooses to run with
diskless logging may be forced periodically to abort some of its transactions.
No guaranteed atomicity, no guaranteed durability
(Logging=0, DurableCommits=0)
For the best response time, applications can turn off logging altogether. However,
by doing so, they risk both a loss of durability and atomicity. Therefore, the nologging mode should be used with care. (See “Logging.” in the Oracle TimesTen
In-Memory Database API and SQL Reference Guide.)
146 Oracle TimesTen In-Memory Database Operations Guide
As with diskless logging mode, the only way to make a transaction durable when
logging is disabled is to checkpoint the data store. Therefore, a system failure
will result in the loss of all transactions that committed after the last checkpoint.
In addition, some operations that would fail atomically with logging enabled will
fail non-atomically with logging disabled. For example, a SQL UPDATE
statement that encounters an error after already having updated one or more rows
will not restore the original contents of the updated rows. When this situation
arises, a warning is returned indicating that the operation has failed nonatomically.
With logging disabled, transaction rollback is not possible as there is no log of
the data store modifications made by the transaction. Therefore all transactions
must commit. Attempts to roll a transaction back in no-logging mode will result
in an error. Row-level locking is also disabled when logging is disabled.
Applications must use data store-level locking.
Because of the many restrictions that exist in non-logging mode, its use should be
limited to applications that can be restarted in the event of failure (loading data
into a new data store, for example). Otherwise uncommitted data may persist,
resulting in inconsistencies.
To use the no-logging mode, applications set Logging=0, which requires the
following additional attribute settings: LockLevel=1, DurableCommits=0, and
LogPurge=0.
Transaction Management and Recovery 147
Controlling durability and logging
Applications can control whether a transaction is durable and whether log files
are created:
• Durability. By default, transactions are durable (DurableCommits=1). To turn
off guaranteed durability, turn off the DurableCommits connection attribute.
A running application can override the delayed transaction durability it set for
its connection by invoking the TimesTen built-in procedure
ttDurableCommit to ensure the durability of a specific transaction.
For a shared data store, durable connections can coexist with connections that
are not guaranteed durable.
• Logging. By default, transaction logs go to disk (Logging=1). To disable
logging completely, set the Logging connection attribute to 0. To enable
diskless logging, set the Logging connection attribute to 2. An application can
switch between logging to disk, diskless logging, and no logging on the same
data store after existing connections have been terminated.
All concurrent connections to a data store must have the same Logging
attribute setting. A request for a connection whose logging attributes are
incompatible with existing connections is rejected unless MatchLogOpts is
set.
When using row-level locking or caching Oracle tables, you must use either
logging to disk or diskless logging.
Using durable commits
The performance cost of durable commits can be mitigated if many threads are
running at the same time, due to an effect called “group commit.” Under group
commit, a single disk write commits a group of concurrent transactions durably.
Group commit does not improve the response time of any given commit
operation, as each durable commit must wait for a disk write to complete, but it
can significantly improve the throughput of a series of concurrent transactions.
When durable commits are used frequently, TimesTen can support more
connections than there are CPUs, as long as transactions are short. This is true
because each connection spends more time waiting to commit than it spends
using the CPU. This is in contrast to applications that do infrequent durable
commits, in which case each connection tends to be very CPU-intensive for the
TimesTen portion of its workload. In the latter case, using more connections than
there are processors will tend to give worse performance, due to CPU contention.
Applications that require lower response time and can tolerate some transaction
loss may elect to perform periodic durable commits. By committing only every
nth transaction durably, or performing a durable commit every n seconds
(typically in a background process), an application can achieve low response
time while maintaining a small window of vulnerability to transaction loss.
148 Oracle TimesTen In-Memory Database Operations Guide
Because a durable commit commits not only itself but all previously-committed
transactions durably — even those performed by other threads or other processes,
an application that commits every n transactions durably only risks the loss of the
last n transactions.
Similarly, an application that performs a durable commit every n seconds, risks
only the transactions that committed during the last n seconds.
To enable periodic durable commits, an application connects with Logging=1
and DurableCommits=0, so transactions commit non-durably by default. When
a durable commit is needed, the application calls the ttDurableCommit built-in
procedure before committing. As with all SQL statements, it is best to preprepare the call to ttDurableCommit if it will be used frequently. The
ttDurableCommit built-in procedure does not actually commit the transaction; it
merely causes the commit to be durable when it occurs.
Another option for avoiding data loss is to use TimesTen replication instead of
durable commits to maintain a copy of the data in two memories. Although two
memories are not as durable as disk, replication can provide higher data
availability by allowing for failover without data store recovery. This type of
trade-off is common in high-performance systems. For more details on TimesTen
replication, see the TimesTen to TimesTen Replication Guide.
Log files
If logging to disk is enabled, log files are created in the same directory as the data
store files unless the LogDir attribute is specified. Multiple log files can exist for
a single data store. The log file names have the form ds_name.logn, where
ds_name is the data store path name given in the data store’s DSN and n is the
log file number, starting at zero.
By default, TimesTen automatically removes archived log files at checkpoint
time. To retain archived log files, set the LogPurge attribute to 0. When the
LogPurge attribute is not set for the data store connection, TimesTen renames
log files no longer needed to perform recovery to ds_name.logn.arch. In this
case, the application is responsible for removing these unneeded log files. See
“LogPurge” on page 38 for details on purging log files.
When a log file exceeds the value of LogFileSize attribute, TimesTen closes that
file and begins a new log file.
Transaction Management and Recovery 149
Concurrency control
Transaction isolation allows each active transaction to operate as if there were no
other transactions active in the system. TimesTen supports two transaction
isolation levels: ANSI Serializable and ANSI Read_Committed isolation.
Transaction isolation levels
• In ANSI Serializable isolation, each transaction acquires locks on all data
items that it reads or writes. It holds these locks until it commits or rolls back.
As a result, a row that has been read by one transaction cannot be updated or
deleted by another transaction until the original transaction terminates.
Similarly, a row that has been inserted, updated or deleted by one transaction
cannot be accessed in any way by another transaction until the original
transaction terminates.
Repeatable reads are assured: a transaction that executes the same query
multiple times is guaranteed to see the same result set each time. Other
transactions cannot UPDATE or CREATE VIEW any of the returned rows,
nor can they INSERT a new row that satisfies the query predicate.
In this isolation level, readers can block writers and writers can block readers
and other writers.
• In ANSI Read_Committed isolation, each transaction acquires locks only on
the items that it writes. Items read by SELECT statements, and the SELECT
portion of INSERT SELECT statements, are not locked. This is the default
isolation level for TimesTen.
In this isolation level, readers do not block writers, nor do writers block
readers, even when they read and write the same data items. To allow readers
and writers to access the same items without blocking, writers create private
copies of the items that they update. These private copies become public when
the transaction commits, or are discarded if the transaction rolls back.
Therefore, when a transaction reads an item that has been updated by another
in-progress transaction, it sees the state of that item before it was updated. It
cannot see an uncommitted state.
Non-repeatable reads are possible in this isolation level. If a Read_Committed
transaction executes the same query multiple times, the commit of an updater
transaction may cause it to see different results.
All data access in TimesTen uses locking or copying to provide isolation, with
the exception of exclusive-mode connections (see “ExclAccess.” in the Oracle
TimesTen In-Memory Database API and SQL Reference Guide), which are
always isolated since they prevent other connections to the data store.
Applications set the transaction isolation level either using the
SQLSetConnectOption ODBC function with the SQL_TXN_ISOLATION flag,
or by setting the Isolation connection attribute.
150 Oracle TimesTen In-Memory Database Operations Guide
To ensure that materialized views are always in a consistent state, all view
maintenance operations are effectively performed under Serializable isolation,
even when the transaction is otherwise in Read_Committed isolation. This means
that the transaction will obtain read locks for any data items read during view
maintenance. However, the transaction will release these read locks at the end of
the INSERT, UPDATE or CREATE VIEW statement that triggered the view
maintenance instead of holding them until it terminates.
Locking granularities
TimesTen supports row-level locking and data store-level locking:
• With row-level locking, transactions usually obtain locks on the individual
rows that they access, although a transaction may obtain a lock on an entire
table if TimesTen determines that doing so would result in better performance.
Row-level locking is the default and is the best choice for most applications,
as it provides the finest granularity of concurrency control. Row-level locking
requires disk logging or diskless logging. It cannot be used if logging is
disabled. Applications can control the circumstances under which TimesTen
will elect to use a table lock by setting optimizer flags. (See “ttOptSetFlag.”in
the Oracle TimesTen In-Memory Database API and SQL Reference Guide.)
To use row-level locking, applications must set the LockLevel connection
attribute to 1 (the default value) or call the ttLockLevel built-in procedure
with the lockLevel parameter set to Row.
• With data store-level locking, every transaction obtains an exclusive lock on
the entire data store, thus ensuring that there is no more than one active
transaction in the data store at any given time. Data store-level locking often
provides better performance than row-level locking, due to reduced locking
overhead. However, its applicability is limited to those applications that never
need to execute multiple concurrent transactions. Data store-level locking is
similar to an exclusive connection (See “ExclAccess.”in the Oracle TimesTen
In-Memory Database API and SQL Reference Guide.) in that both modes of
operation prevent concurrent transactions from accessing the data store.
However, a shared connection with data store-level locking permits multiple
connections to a data store, but allows only one connection to begin a
transaction at a time. Exclusive-access, by contrast, prevents multiple
connections from being made to the data store. With data store-level locking,
every transaction effectively runs in ANSI Serializable isolation, since
concurrent transactions are disallowed. Data store level is required when
logging is disabled. To use data store-level locking, applications set the
LockLevel connection attribute to 0 or call the ttLockLevel built-in
procedure with the lockLevel parameter set to set to DS.
Transaction Management and Recovery 151
Coexistence of different locking levels
Different connections can coexist with different levels of locking, but the
presence of even one connection using data store-level locking leads to reduced
concurrency. For performance information, see “Choose the best method of
locking.” in the Oracle TimesTen In-Memory Database Java Developer’s and
Reference Guide. For information on tuning TimesTen C applications, see
“Choose the best method of locking.” in the Oracle TimesTen In-Memory
Database C Developer’s and Reference Guide.
152 Oracle TimesTen In-Memory Database Operations Guide
Checkpoints
A checkpoint is an operation that saves the state of a data store to disk files,
known as checkpoint files. By default, TimesTen performs “background”
checkpoints at regular intervals. Alternatively, applications can programmatically
initiate checkpoint operations. See “Setting and managing checkpoints” on page
155, for more details.
Each TimesTen data store has two checkpoint files, named dsname.ds0 and
dsname.ds1, where dsname is the data store path name specified in the data
store's DSN. A checkpoint operation identifies the checkpoint file to which the
last checkpoint was written and writes its checkpoint to the other file. Therefore,
the two files always contain the two most recent data store images.
Data store recovery uses these files to recover the most recent transactionconsistent state of the data store after a data store shutdown or system failure. It
identifies the file that contains the more recent of the two checkpoint images and
applies the log to that file's data store image, as appropriate, to recover the up-todate data store state. If any errors occur during this process, or if the more recent
checkpoint image is incomplete (for example, if a system failure occurred while
that checkpoint was begin written), then recovery restarts, using the other
checkpoint file.
TimesTen also creates a dsName.res0 and dsName.res1 file for each data store.
These files are used internally by TimesTen for the creation of logs.
A checkpoint operation has two primary purposes. First, it decreases the amount
of time required for data store recovery, because it provides a more up-to-date
data store image for recovery to begin with. Second, it makes a portion of the log
unneeded for any future data store recovery operation, typically allowing one or
more log files to be deleted. Both of these functions are very important to
TimesTen applications. The reduction in recovery time is important, as the
amount of log needed to recover a data store has a direct impact on the amount of
downtime seen by an application after a system failure. The removal of unneeded
log files is important because it frees disk space that can then be used for new log
files. If these files were never removed, they would eventually consume all
available space in the log directory's file system, causing data store operations to
fail due to log space exhaustion.
For these reasons, either TimesTen applications should checkpoint their data
stores periodically or you should set the data store first connection attributes
CkptFrequency and/or CkptLogVolume, which determine how often TimesTen
performs a “background” checkpoint.
Checkpointing may generate a large amount of I/O activity and have a long
execution time depending on the size of the data store and the number of data
store changes since the most recent checkpoint.
Transaction Management and Recovery 153
Types of checkpoints
TimesTen supports two kinds of data store checkpoints:
Transaction-consistent checkpoints
Transaction-consistent checkpoints, also known as blocking checkpoints, obtain
an exclusive lock on the data store for a portion of the checkpoint, blocking all
access to the data store during that time. The resulting checkpoint image contains
the effects of all transactions that committed before the checkpointer obtained its
lock. Because no transactions can be active while the data store lock is held, no
modifications made by in-progress transactions are included in the checkpoint
image.
Transaction-consistent checkpoints can be used with any of the three logging
modes (disk logging, diskless logging and no logging). When disk logging is in
effect, the log will be used during recovery to reapply the effects of transactions
that committed durably after the checkpoint completed. To request a transactionconsistent checkpoint, an application uses the ttCkptBlocking built-in
procedure. The actual checkpoint will be delayed until the requesting transaction
commits or rolls back. If a transaction-consistent checkpoint is requested for a
data store for which both checkpoint files are already up to date then the
checkpoint request will be ignored.
Fuzzy or non-blocking checkpoints
Fuzzy checkpoints, or non-blocking checkpoints, allow transactions to execute
against the data store while the checkpoint is in progress. Fuzzy checkpoints do
not obtain locks of any kind, and therefore have a minimal impact on other data
store activity. Because these other transactions may modify the data store while it
is being written to the checkpoint file, the resulting checkpoint image may
contain some effects of transactions that were active while the checkpoint was in
progress. Furthermore, different portions of the checkpoint image may reflect
different points in time. For example, one portion may have been written before a
given transaction committed, while another portion was written afterward. The
term “fuzzy checkpoint” derives its name from this fuzzy state of the data store
image. TimesTen background checkpoints are always non-blocking.
To recover from a fuzzy checkpoint, TimesTen uses the log both to bring the
various portions of the checkpoint into a consistent state with one another and to
reapply the effects of transactions that committed durably after the checkpoint
completed. For this reason, fuzzy checkpoints can only be used when disk
logging is in effect. To request a fuzzy checkpoint, an application uses the ttCkpt
built-in procedure. If disk logging is in effect, this procedure will issue a fuzzy
checkpoint. If diskless logging is in effect, or if logging is disabled, then a
blocking (transaction-consistent) checkpoint will be requested. As with all
blocking checkpoints, the actual checkpoint will be delayed until the requesting
transaction commits or rolls back.
154 Oracle TimesTen In-Memory Database Operations Guide
Setting and managing checkpoints
By default, TimesTen performs automatic non-blocking checkpoints in the
background if Logging=1. In this case, background checkpoints are nonblocking. (See “Fuzzy or non-blocking checkpoints” on page 154.)
Several data store attributes and built-in procedures are available to set, manage
and monitor checkpoints. These include:
• CkptFrequency attribute
• CkptLogVolume attribute
• CkptRate attribute
• ttCkpt built-in procedure
• ttCkptBlocking built-in procedure
• ttCkptConfig built-in procedure
• ttCkptHistory built-in procedure
TimesTen also automatically performs a transaction-consistent checkpoint when
the last application disconnects from the data store, unless the RAM policy is
always. For temporary data stores with Logging=1, checkpoints are still taken to
purge the log files. For non-disk logging Temporary data stores, background
checkpointing is off. See “Transaction-consistent checkpoints.”
In addition, applications can programatically perform a checkpoint using the
ttCkpt or ttCkptBlocking built in procedure. For details on how to call the
ttCkpt and other TimesTen built-in procedures from a C or Java program, see
“Calling TimesTen built-in procedures within C applications.” in the Oracle
TimesTen In-Memory Database C Developer’s and Reference Guide or “Calling
TimesTen built-in procedures.” in the Oracle TimesTen In-Memory Database
Java Developer’s and Reference Guide.
By default, TimesTen performs background checkpoints at regular intervals. If an
application attempts to perform a checkpoint while a background checkpoint is in
progress, TimesTen returns an error to the application. To turn off background
checkpointing, set CkptFrequency=0 and CkptLogVolume=0. You can also use
the built-in procedure ttCkptConfig to configure background checkpointing or
turn it off. The values set by ttCkptConfig take precedence over those set with
the data store attributes.
Using these attributes and the built-in procedure, you can configure TimesTen to
checkpoint either when the log files contain a certain amount of data or at a
specific frequency. For information on default values and usage, see the Oracle
TimesTen In-Memory Database API and SQL Reference Guide.
You need to be aware when background checkpointing is occurring. If the
application attempts to back up a data store while a background checkpoint is in
process, TimesTen waits until the checkpoint finishes and before beginning the
backup. If a background checkpoint starts while a backup is in progress, the
Transaction Management and Recovery 155
background checkpoint will not take place until the backup has completed. If a
background checkpoint starts while an application-initiated checkpoint is in
progress, then an error results.
You can use, the ttCkptHistory built-in procedure to display the history of last
eight checkpoints, the settings for checkpoint frequency and log volume and the
status of in-progress checkpoint disk writes.
Setting the checkpoint rate for background checkpoints
By default, there is no limit to the rate at which checkpoints are written to disk.
You can use the CkptRate attribute or the ttCkptConfig built-in procedure to set
the maximum rate at which background checkpoints are written to disk, if you
would like to have control over the rate. The rate is expressed in MB per second.
Checkpoints taken during recovery and final checkpoints do not honor this rate;
their rate is unlimited.
See the Oracle TimesTen In-Memory Database API and SQL Reference Guide for
details on using these features.
Setting a rate too low can cause checkpoints to take an excessive amount of time
and cause the following problems;
• Delay the purging of unneeded log files
• Delay the start of backup operations
• Increase recovery time.
When choosing a rate, you should take into consideration the amount of data
written by a typical checkpoint and the amount of time checkpoints usually take.
Both of these pieces of information are available through the ttCkptHistory
built-in procedure.
In addition, you can monitor the progress of a running checkpoint by looking at
the Percent_Complete column of the ttCkptHistory result set. If a running
checkpoint appears to be progressing too slowly, the rate can be increased by
calling the ttCkptConfig built-in procedure. If a call to ttCkptConfig changes
the rate, the new rate takes effect immediately, affecting even the running
checkpoint.
A simple method of calculating the checkpoint rate is:
1.
Call the ttCkptHistory built-in procedure.
2.
For any given checkpoint, subtract the starttime from the endtime.
3.
Divide the number of bytes written by this elapsed time in seconds to get the
number of bytes per second.
4.
Divide this number by 1024*1024 to get the number of megabytes per second.
156 Oracle TimesTen In-Memory Database Operations Guide
When setting the checkpoint rate, some other things to consider are:
• The specified checkpoint rate is only approximate. The actual rate of the
checkpoint may be below the specified rate, depending on the hardware,
system load and other factors.
• Calculating the actual checkpoint rate using the above method may produce a
result that is below the requested rate. This is because the starttime/endtime
interval includes other checkpoint activities in addition to the writing of dirty
blocks to the checkpoint file.
• The Percent_Complete field of the ttCkptHistory call may show 100 percent
before the checkpoint is actually complete. The Percent_Complete field
shows only the progress of the writing of dirty blocks and does not include
additional bookkeeping at the end of the checkpoint.
• When adjusting the checkpoint rate, you may also need to adjust the
checkpoint frequency, as a slower rate makes checkpoints take longer, which
effectively increases the minimum time between checkpoint beginnings.
Transaction Management and Recovery 157
158 Oracle TimesTen In-Memory Database Operations Guide
8
Data Store Performance Tuning
An application using the TimesTen Data Manager should obtain an order of
magnitude performance improvement in its data access over an application using
a traditional DBMS. However, poor application design and tuning can erode the
TimesTen advantage. This chapter discusses factors that can affect the
performance of a TimesTen application. These factors range from subtle, such as
data conversions, to more overt, such as preparing a command at each execution.
This chapter explains the full range of these factors, with a section on each factor
indicating:
• How the problem can be detected
• Whether the potential performance impact is large, medium, small or variable.
• Where the performance gain may be
• What the tradeoffs are
As discussed throughout this chapter, many performance problems can be
identified by examining the SYS.MONITOR table.
Topics are:
• System and data store tuning
• Client/server tuning
• SQL tuning
• Improving performance of materialized views
• Scaling to Multiple CPUs
• XLA acknowledgement modes
For information on tuning TimesTen Java applications, see Chapter 5,
“Application Tuning in the Oracle TimesTen In-Memory Database Java
Developer’s and Reference Guide. For information on tuning TimesTen C
applications, see Chapter 5, “Application Tuning in the Oracle TimesTen InMemory Database C Developer’s and Reference Guide.
159
System and data store tuning
Performance
impact:
Large
Provide enough memory
Configure your system so that the entire data store fits in main memory. The use
of virtual memory substantially decreases performance. You will know that the
data store (or working set) does not fit if a performance monitoring tool shows
excessive paging or virtual memory activity.
You may have to add physical memory or configure the system software to allow
a large amount of shared memory to be allocated to your process(es). TimesTen
includes the ttSize utility to help you estimate the size of your data store.
Performance
impact:
Variable
Size your data store correctly
When you create a data store, you are required to specify a data store size.
Specifically, you specify a size for the permanent partition of the data store and a
size for the temporary partition of the data store.
Once you have created a data store, you can increase the size of the permanent
partition of the data store and you can either increase or decrease the temporary
partition of the data store. See “Specifying the size of a data store” on page 46.
To make size estimates, use the ttSize utility or run the application until you can
make a reasonable estimate.
Another method for estimating size requirements is to use the SYS.MONITOR
table. The columns PERM_ALLOCATED_SIZE, TEMP_ALLOCATED_SIZE,
PERM_IN_USE_SIZE and TEMP_IN_USE_SIZE show (in KB units) the
currently allocated size of the data store, and the in-use size of the data store. The
system updates this information each time a connection is made or released and
each time a transaction is committed or rolled back.
You can monitor block-level fragmentation in the data store by using
ttBlockInfo.
Performance
impact:
Large
Performance
impact:
Large
Use multi-processor optimizations if appropriate
Applications running on single processor machines should set SMPOptLevel to
0. If an application running on a single processor machine sets SMPOptLevel to
greater than 0, it will experience a drop in performance due to the increased use
of synchronization primitives.
Increase LogBuffSize if needed
Increasing the value of LogBuffSize can have a substantial positive performance
impact. If LOG_BUFFER_WAITS is increasing, then increase the value of
LogBuffSize.
160 Oracle TimesTen In-Memory Database Operations Guide
The trade-off is that more transactions are buffered in memory and may be lost if
the process crashes. If DurableCommits are enabled, increasing the default
LogBuffSize value does not improve performance.
Performance
impact:
Variable
Use temporary data stores if appropriate
A TimesTen data store may be permanent or Temporary. A temporary data store
disappears when the last connection goes away or when there is a system or
application failure.
If you do not need to save the data store to disk, you can save checkpoint
overhead by creating a temporary data store.
Temporary data stores are never fully checkpointed to disk, although the log is
periodically written to disk when logging to disk is enabled. Checkpoint
operations can have significant overhead for permanent data stores, depending on
data store size and activity, but have very little impact for temporary data stores.
Checkpoints are still necessary to remove log files.
Performance
impact:
Large
Avoid connection overhead
By default, TimesTen loads an idle data store (a data store with no connections)
into memory when a first connection is made to it. When the final application
disconnects from a data store, a delay occurs when the data store is written to
disk. If applications are continually connecting and disconnecting from a data
store, the data store may be loaded and unloaded to/from memory continuously,
resulting in excessive disk I/O and poor performance. Similarly, if you are using
a very large data store you may want to pre-load the data store into memory
before any applications attempt to use it.
To avoid the latency of loading a data store into memory, you can change the
RAM policy of the data store to allow data stores to always remain in memory.
The trade-off is that since the data store is never unloaded from memory, a final
disconnect checkpoint never occurs. So, applications should checkpoint the data
store explicitly in order to reduce the disk space taken up by log files.
Alternatively, you can specify that the data store remain in memory for a
specified interval of time and accept new connections. If no new connections
occur in this interval, TimesTen unloads the data store from memory and
checkpoints it. You can also specify a setting to allow a system administrator to
load and unload the data store from memory manually.
To change the RAM policy of a data store, use the ttAdmin utility.
Perfect
impact:
large
Load the data store into RAM when duplicating
When you duplicate a data store, use the -ramLoad option of the ttAdmin utility.
This places the data store in memory, available for connections, instead of
unloading it with a blocking checkpoint. See “Avoid connection overhead”.
Data Store Performance Tuning 161
Performance
impact:
Medium
Avoid OS paging at load time
All of the TimesTen platform operating systems implement a dynamic file
system buffer pool in main memory. If this buffer pool is allowed to be large,
TimesTen and the operating system both retain a copy of the file in memory,
causing some of the TimesTen shared segment to be paged out.
This behavior may not occur for data stores that are less than half of the installed
memory size. On some systems, it is possible to limit the amount of main
memory used by the file system. On other systems, this effect is less pronounced.
On HP-UX, Solaris and Linux systems, consider using the MemoryLock
attribute to specify whether the data store should be locked in memory. If used,
the data store cannot be paged out.
On HP-UX, consider the settings for the kernel parameters dbc_min_pct and
dbc_max_pct. These parameters control the minimum and maximum percent of
real memory devoted to the file system. The default maximum is 50 percent.
TimesTen recommends reducing the maximum to 10 percent.
Performance
impact:
Medium
Performance
impact:
large
Consider special options for maintenance
During special operations such as initial loading, you can choose different
options than you would use during normal operations. In particular, consider
turning Logging off and using data store-level locking for bulk loading; an
example would be using ttBulkCp or ttMigrate. These choices can improve
loading performance by a factor of two.
Check your driver
There are two versions of the TimesTen Data Manager driver for each platform, a
debugging version and a production version. Unless you are actually debugging,
use the production version. The debugging library can be significantly slower.
See “Specify the DSN” on page 40 and “Specify the ODBC driver” on page 37
for a description of the TimesTen Data Manager drivers for the different
platforms.
On Windows, make sure that applications that use the ODBC driver manager use
a DSN that accesses the correct TimesTen driver. Make sure that direct-linked
applications are linked with the correct TimesTen driver. An application can call
the ODBC SQLGetInfo function with the SQL_DRIVER_NAME argument to
determine which driver it is using.
Performance
impact:
Large
Enable tracing only as needed
Both ODBC and JDBC provide a trace facility to help debug applications. For
performance runs, make sure that tracing is disabled except when debugging
applications.
To turn the JDBC tracing on, use:
162 Oracle TimesTen In-Memory Database Operations Guide
DriverManager.setLogStream method:
DriverManager.setLogStream(new PrintStream(System.out, true));
By default tracing is off. You must call this method before you load a JDBC
driver. Once you turn the tracing on, you cannot turn it off for the entire
execution of the application.
Performance
impact:
Variable
Investigate alternative JVMs
Performance
impact:
Large
Adjust log buffer size and CPU for a large number of
subscribers
JRockit, IBM and HP provide JVMs that may perform better than the Sun JVM.
If you are planning a replication scheme that includes a large number of
subscribers, then ensure the following:
• The setting for LogBuffSize should result in the value of LOG_FS_READS
in the SYS.MONITOR table being 0 or close to 0. This ensures that the
replication agent does not have to read any log records from disk. If the value
of LOG_FS_READS is increasing, then increase the log buffer size.
• CPU resources are adequate. The replication agent on the master data store
will spawn a thread for every subscriber data store. Each thread reads and
processes the log independently and needs adequate CPU resources to make
progress.
Data Store Performance Tuning 163
Client/server tuning
Performance
impact:
Large
Work locally when possible
Performance
impact:
Variable
Use shared memory segment as IPC when client and
server are on the same machine
Using TimesTen Client to access data stores on a remote server machine can add
network overhead to your connections. Whenever possible, write your
applications to access the TimesTen Data Manager locally, and link the
application directly with the TimesTen Data Manager.
The TimesTen Client normally communicates with TimesTen Server using TCP/
IP sockets. If both the TimesTen Client and TimesTen Server are on the same
machine, client applications show improved performance by using a shared
memory segment or a UNIX domain socket for inter-process communication
(IPC).
To use a shared memory segment as IPC, you must set the server options in the
ttendaemon.options file. For a description of the server options, see “Modifying
the TimesTen web server options” in Chapter 4 of the Oracle TimesTen InMemory Database Operations Guide.
In addition, applications that use shared memory for IPC must use a logical
server name (for the Client DSN) with ttShmHost as the Network Address. For
more information, see “Creating and configuring Client DSNs on UNIX” on
page 67.
This feature may require a significant amount of shared memory. The TimesTen
Server pre-allocates the shared memory segment irrespective of the number of
existing connections or the number of statements within all connections.
If your application is running on a UNIX machine and you are concerned about
memory usage, the applications using TimesTen Client ODBC driver may
improve the performance by using UNIX domain sockets for communication.
The performance improvement when using UNIX domain sockets is not as large
as when using ShmIPC.
Applications that take advantage of UNIX domain sockets for local connections
must use a logical server name (for the Client DSN) with ttLocalHost as the
Network Address. For more information, see “Creating and configuring Client
DSNs on UNIX” on page 67. In addition, make sure that your system kernel
parameters are configured to allow the number of connections you require. See
“Installation prerequisites” in the Oracle TimesTen In-Memory Database
Installation Guide.
164 Oracle TimesTen In-Memory Database Operations Guide
Enable/Disable TT_PREFETCH_CLOSE for SELECT
queries
Performance
impact:
Variable
With the TimesTen connection option TT_PREFETCH_CLOSE, an application
using TimesTen Client Driver can have better performance for certain SELECT
queries. This is an ODBC statement option that can be set with the
SQLSetStatementOption. In order to use the option, the application must
explicitly turn ON or OFF. The option is designed to remove network I/O for
closing a cursor and committing.
TimesTen Server already pre-fetches a full or partial result set from the data store
during the execution of SQLExecute and SQLExecDirect. TimesTen buffers this
data at the TimesTen Client. This is done to reduce network I/O between the
Client and the Server. With AUTOCOMMIT off, the Server also closes the
cursor if the end of the result set is reached.
For read-only transactions when TT_PREFETCH_CLOSE is on, the Server
commits the transaction if AUTOCOMMIT is off. If AUTOCOMMIT is on, the
Server closes the cursor and commits the transaction.
Note: The TT_PREFETCH_CLOSE option is only useful for Client
applications. If used in a TimesTen Data Manager application, TimesTen ignores
it.
Normally, an application should turn on the TT_PREFETCH_CLOSE option
when all of the following criteria are satisfied:
• No other cursor is open.
• The transaction is a read only transaction.
• The query is not a SELECT…….FOR UPDATE.
Once the application has committed such a transaction, the application should
turn off the option unless the next transaction of the application also desires to
use this feature.
Note: This option should be used cautiously. If a transaction has an INSERT,
UPDATE or DELETE statement while this option is set, the SERVER may
commit those changes although the application never issued a commit.
The following examples show how to use the TT_PREFETCH_CLOSE option
with JDBC and ODBC.
Example 8.1
To use the TT_PREFETCH_CLOSE option with JDBC:
SQLSetConnectOption (hdbc, TT_PREFETCH_CLOSE,
TT_PREFETCH_CLOSE_ON);
SQLExecDirect (hstmt, “SELECT * FROM T”, SQL_NTS);
Data Store Performance Tuning 165
while (SQLFetch (hstmt) != SQL_NO_DATA_FOUND)
{
// do the processing
}
SQLFreeStmt (hstmt, SQL_CLOSE);
SQLTransact (henv, hdbc, SQL_COMMIT);
SQLSetConnectOption (hdbc, TT_PREFETCH_CLOSE,
TT_PREFETCH_CLOSE_OFF);
Example 8.2
To use the TT_PREFETCH_CLOSE option with ODBC:
con = DriverManager.getConnection ("jdbc:timesten:client:" + DSN);
stmt = con.createStatement();
import com.timesten.sql
………..
………..
con.setTtPrefetchClose(boolean);
rs = stmt.executeQuery("select * from t");
while(rs.next())
{
// do the processing
}
import com.timesten.sql
....
try {
((TimesTenConnection)con).setTtPrefetchClose(true);
}
catch (SQLException) {
...
}
rs.close();
con.commit();
con.setTtPreFetchClose (false);
Performance
impact:
Large
Use a connection handle when calling SQLTransact
An application can make a call to SQLTransact with either SQL_NULL_HDBC
and a valid environment handle:
SQLTransact (ValidHENV, SQL_NULL_HDBC, fType)
or a valid connection handle:
166 Oracle TimesTen In-Memory Database Operations Guide
SQLTransact (SQL_NULL_HENV, ValidHDBC, fType).
When using a valid environment handle, the TimesTen driver tries to commit/
rollback transactions on all connection handles that are in a connected state. In
Client/Server mode, this causes at least n network I/O operations, where n is the
number of connection handles that are in a connected state. Normally, network I/
O operations are much more expensive than TimesTen database operations.
Hence, if the intention of the application is simply to commit/rollback on a single
connection, it should use a valid connection handle when calling SQLTransact.
Data Store Performance Tuning 167
SQL tuning
After you have determined the overall logging, locking and I/O strategies, make
sure that the individual SQL statements are executed as efficiently as possible.
Performance
impact:
Large
Tune statements and use indexes
Verify that all statements are executed efficiently. For example, use queries that
reference only the rows necessary to produce the required result set. If only col1
from table t1 is needed, use the statement:
SELECT col1 FROM t1...
instead of using:
SELECT * FROM t1...
Chapter 9, “The TimesTen Query Optimizer,” describes how to view the plan
that TimesTen uses to execute a statement. Alternatively, you can use the ttIsql
showplan command to view the plan. View the plan for each frequently executed
statement in the application. If indexes are not used to evaluate predicates,
consider creating new indexes or rewriting the statement or query so that indexes
can be used. For example, indexes can only be used to evaluate WHERE clauses
when single columns appear on one side of a comparison predicate (equalities
and inequalities), or in a BETWEEN predicate.
If this comparison predicate is evaluated often, it would therefore make sense to
rewrite
WHERE c1+10 < c2+20
to
WHERE c1 < c2+10
and create an index on c1.
The presence of indexes does slow down write operations such as UPDATE,
INSERT, DELETE and CREATE VIEW. If an application does few reads but
many writes to a table, an index on that table may hurt overall performance rather
than help it.
The FIRST keyword can be used to operate on a specific number of rows in the
SQL statements, SELECT, UPDATE and DELETE. This attribute can improve
throughput and response time. Alternatively, if an application plans to fetch at
most one row for a query, and a unique index isn’t being used to fetch the row,
the application should set SQL_MAX_ROW_COUNT to 1. See the Oracle
TimesTen In-Memory Database API and SQL Reference Guide.
Occasionally, the system may create a temporary index to speed up query
evaluation. If this happens frequently, it is better for the application itself to
create the index. The CMD_TEMP_INDEXES column in the MONITOR table
indicates how often a temporary index was created during query evaluation.
168 Oracle TimesTen In-Memory Database Operations Guide
Performance
impact:
Variable
Select hash or T-tree indexes appropriately
The TimesTen Data Manager supports both hash and T-tree indexes. Hash
indexes are created for tables that declare a PRIMARY KEY. T-tree indexes are
created with the CREATE INDEX statement.
The index structures have different strengths. Hash indexes are faster than T-tree
indexes for exact key lookups on all columns of the primary key. However, hash
indexes have the following restrictions:
• Hash indexes do not speed up queries on LESS THAN or GREATER THAN
comparisons on indexed columns.
• All columns must appear in the WHERE clause.
• Hash indexes can only be created on the columns of the PRIMARY KEY;
these columns cannot be set to NULL, cannot be changed once a record is
inserted and only allow unique values of the indexed columns to be inserted.
T-tree indexes can also speed up exact key lookups but are more flexible and can
speed up other queries as well. Select a T-tree index if your queries include LESS
THAN or GREATER THAN comparisons. T-tree indexes can also be used to
speed up “prefix” queries. A prefix query has equality conditions on all but the
last key column that is specified. The last column of a prefix query can have
either an equality condition or an inequality condition.
Consider the following table and index definitions:
CREATE TABLE T(i1 integer, i2 integer, i3 integer, ...);
CREATE INDEX IXT on T(i1, i2, i3);
The index IXT can be used to speed up the following queries:
SELECT * FROM T WHERE i1>12;
SELECT * FROM T WHERE i1=12 and i2=75;
SELECT * FROM T WHERE i1=12 and i2 BETWEEN 10 and 20;
SELECT * FROM T WHERE i1=12 and i2=75 and i3>30;
The index IXT will not be used for queries like:
SELECT * FROM T WHERE i2=12;
because the prefix property is not satisfied. There is no equality condition for i1.
The index IXT will be used, but matching will only occur on the first two columns for queries like:
SELECT * FROM T WHERE i1=12 and i2<50 and i3=630;
T-tree indexes have a dynamic structure that adjusts itself automatically to
accommodate changes in table size. A T-tree index can be either unique or nonunique and can be declared over nullable columns. It also allows the indexed
column values to be changed once a record is inserted. A T-tree index is likely to
be more compact than an equivalent hash index.
Data Store Performance Tuning 169
Size hash indexes appropriately
Performance
impact:
Variable
TimesTen uses hash indexes to enforce primary key constraints. The number of
buckets used for the hash index is determined by the PAGES parameter specified
in the UNIQUE HASH ON clause of the CREATE TABLE statement. The value
for PAGES should be the expected number of rows in the table divided by 256. A
smaller value may result in a greater number of collisions, decreasing
performance, while a larger value may provide somewhat increased performance
at the cost of extra space used by the index.
If the number of values to be indexed varies dramatically, it is best to err on the
side of a large index. If the size of a table cannot be accurately predicted,
consider using a T-tree index with CREATE INDEX. Also, consider the use of
unique indexes when the indexed columns are large CHAR or binary values or
when many columns are indexed. Unique indexes may be faster than hash
indexes in these cases.
If the performance of record inserts degrades as the size of the table gets larger, it
is very likely that you have underestimated the expected size of the table. You
can resize the hash index by using the ALTER TABLE statement to reset the
PAGES value in the UNIQUE HASH ON clause.
Performance
impact:
Variable
Performance
impact:
Variable
Use foreign key constraint appropriately
The declaration of a foreign key has no performance impact on SELECT queries,
but it slows down the INSERT and UPDATE operations on the table that the
foreign key is defined on and the UPDATE and DELETE operations on the table
referenced by the foreign key. The slow down is proportional to the number of
foreign keys that either reference or are defined on the table.
Computing exact or estimated statistics
If statistics are available on the data in the data store, the TimesTen optimizer
uses them when preparing a command to determine the optimal path to the data.
If there are no statistics, the optimizer uses generic guesses about the data
distribution. If you have examined the plans generated for your statements (see
Chapter 9, “The TimesTen Query Optimizer”) and you think they may not be
optimal, consider computing statistics before preparing your statements and reexamining the plans.
If you haven't examined the plans, we generally recommend computing statistics
since the information is likely to result in more efficient plans.
There are two built-in procedures for computing statistics: ttOptUpdateStats
and ttOptEstimateStats. ttOptUpdateStats looks at every row of the table(s) in
question and computes exact statistics. ttOptEstimateStats looks at only a
sampling of the rows of the table(s) in question and produces estimated statistics.
Estimating statistics can be considerably faster but can also result in less accurate
170 Oracle TimesTen In-Memory Database Operations Guide
statistics. In general, if time is not an issue, it's best to call ttOptUpdateStats.
But estimation is preferable if overall application performance may be affected.
As a rule of thumb, computing statistics with a sample of 10 percent is about ten
times faster than computing exact statistics and generally results in the same
execution plans. Since computing statistics is a time-consuming operation, it’s
best to compute statistics once after loading your data store (and before preparing
commands), and then periodically only if the composition of your data changes
substantially.
Performance
impact:
Variable
Avoid ALTER TABLE
The ALTER TABLE statement allows applications to add columns to a table and
to drop columns from a table. Although the ALTER TABLE statement itself runs
very quickly in most cases, the modifications it makes to the table can cause
subsequent operations on the table to run more slowly. The actual performance
degradation the application experiences varies with the number of times the table
has been altered and with the particular operation being performed on the table.
Dropping VARCHAR and VARBINARY columns is slower than dropping
columns of other data types since a table scan is required to free the space
allocated to the existing VARCHAR and VARBINARY values in the column to
be dropped.
Performance
impact:
Variable
Avoid nested queries
TimesTen supports nested queries with some limitations. However, performance
varies and is generally not optimal. See the Oracle TimesTen In-Memory
Database API and SQL Reference Guide for details on subqueries.
Data Store Performance Tuning 171
Improving performance of materialized views
Performance
impact:
Variable
Limit number of join rows
Performance
impact:
Variable
Use indexes on join columns
Larger numbers of join rows decrease performance. You can limit the number of
join rows by controlling the join condition. For example, use only equality
conditions that map one row from one table to one or at most a few rows from the
other table.
Create indexes on the columns of the detail table that are specified in the
SELECT statement that creates the join. Also consider creating an index on the
materialized view itself. This can improve the performance of keeping the
materialized view updated.
If an UPDATE or DELETE operation on a detail table is often based on a
condition on a column, try to create an index on the materialized view on this
column if possible.
For example, CustOrder is a materialized view of customer orders, based on two
tables. The tables are Customer and bookOrder. The former has two columns
(custNo and custName) and the latter has three columns (ordNo, book, and
custNo). If you often update the bookOrder table to change a particular order by
using the condition bookOrder.ordNo=const, then create an index on
CustOrder.ordNo. On the other hand, if you often update based on the condition
bookOrder.custNo=const, then create an index on CustOrder.custNo.
If you often UPDATE using both conditions and cannot afford to create both
indexes, you may want to add bookOrder.rowId in the view and create an index
on it instead. In this case, TimesTen updates the view for each detail row update
instead of updating all of the rows in the view directly and at the same time. The
scan to find the row to be updated is an index scan instead of a row scan, and no
join rows need to be generated.
If ViewUniqueMatchScan is used in the execution plan, it is a sign that the
execution may be slower or require more space than necessary. A
ViewUniqueMatchScan is used to handle an update or delete that cannot be
translated to a direct update or delete of a materialized view, and there is no
unique mapping between a join row and the associated row in the materialized
view. This can be fixed by selecting a unique key for each detail table that is
updated or deleted.
Performance
impact:
Variable
Avoid unnecessary updates
Try not to update a join column or a “group by” column because this involves
deleting the old value and inserting the new value.
172 Oracle TimesTen In-Memory Database Operations Guide
Try not to update an expression that references more than one table. This may
disallow direct update of the view because TimesTen may perform another join
operation to get the new value when one value in this expression is updated.
View maintenance based on an update or delete is more expensive when:
• The view cannot be updated directly. For example, not all columns specified
in the detail table UPDATE or DELETE statement are selected in the view, or
• There is not an indication of a one-to-one mapping from the view rows to the
join rows.
For example:
CREATE MATERIALIZED VIEW v1 AS SELECT x1 FROM t1, t2 WHERE x1=x2;
DELETE FROM t1 WHERE y1=1;
The extra cost comes from the fact that extra processing is needed to ensure that
one and only one view row is affected due to a join row.
The problem is resolved if either x1 is UNIQUE or a unique key from t1 is
included in the select list of the view. ROWID can always be used as the unique
key.
Performance
impact:
Variable
Performance
impact:
Variable
Avoid changes to the inner table of an outer join
Since outer join maintenance is more expensive when changes happen to an inner
table, try to avoid changes to the inner table of an outer join. When possible,
perform INSERT operations on an inner table before inserting into the associated
join rows into an outer table. Likewise, when possible perform DELETE
operations on the outer table before deleting from the inner table. This avoids
having to convert non-matching rows into matching rows or vice versa.
Limit number of columns in a view table
The number of columns projected in the view SelectList can impact performance.
As the number of columns in the select list grows, the time to prepare operations
on detail tables increases. In addition, the time to execute operations on the view
detail tables also increases. Do not select values or expressions that are not
needed.
The optimizer considers the use of temporary indexes when preparing operations
on detail tables of views. This can significantly slow down prepare time,
depending upon the operation and the view. If prepare time seems slow, consider
using ttOptSetFlag to turn off temporary ttree indexes and temporary hash scans.
Data Store Performance Tuning 173
Scaling to Multiple CPUs
Performance
impact:
Variable
Run the demo applications as a prototype
One way to see what sort of scaling you can expect from TimesTen is to run one
of the scalable demo applications, such as tptbm, on your system.
The tptbm application has a parameter -proc that lets you vary the number of
processes that execute TimesTen operations. In addition, it has other parameters
that let you specify the transaction mix of READs, WRITEs and INSERTs.
Run tptbm -help to see the full list of options. For example, you can specify
whether it uses a hash index or a t-tree index.
By default the demo does one operation per transaction. You can use the -ops
options to add more operations in a transaction to better model your application.
Larger transactions may scale better or worse, depending on the application
profile.
Run multi-processor versions of the demo to evaluate how your application can
be expected to perform on systems that have multiple CPUs. If the demo scales
well, but your application scales poorly, you might try simplifying your
application to see where the issue is. Some users “stub out” the TimesTen calls
and find they still have bad scaling, and they discover an issue in their
application.
You may find that some simulated application data is not being generated
properly, so all the operations are accessing the same few rows. That type of
localized access will greatly inhibit scalability if the accesses involve changes to
the data.
Performance
impact:
Variable
Limit database-intensive connections per CPU
Check the LOCK_TIMEOUTS or LOCK_GRANTS_WAIT fields in the
SYS.MONITOR table. If they have high values, this may indicate undue
contention, which can lead to poor scaling.
Because TimesTen is quite CPU-intensive, optimal scaling is achieved by having
at most one database-intensive connection per CPU. If you
have a 4-CPU system or a 2-CPU system with hyperthreading, then a
4-processor application will run well, but an 8-processor application will not
perform well. The contention between the active threads will be too high. The
only exception to this rule is when many transactions are committed durably. In
this case, the connections are not very CPU-intensive because of the increase in I/
O operations to disk, and so the machine can support many more concurrent
connections. We have seen up to 60 connections on a 4 CPU system.
174 Oracle TimesTen In-Memory Database Operations Guide
Performance
impact:
Variable
Use read operations when available
Performance
impact:
Variable
Limit prepares, re-prepares and connects
Read operations scale better than write operations. Make sure that the read/write
balance reflects the real-life workload of your application.
Prepares do not scale. Make sure that you pre-prepare commands that are
executed more than once. The CMD_PREPARES and CMD_REPREPARES
columns of the SYS.MONITOR table indicate how often commands were
prepared or automatically re-prepared (due to creation or deletion of indexes). If
either has a high value, modify your application to do connection pooling, so that
connects and disconnects are rare events.
Connects do not scale. Make sure that you pre-prepare commands that are
executed more than once. Look at the DS_CONNECTS field in the
SYS.MONITOR table. If the field has a high value, modify your application to
do connection pooling, so that connects and disconnects are rare events.
If your application uses more than 64 active connections, you may wan to set the
CkptRate attribute to the number of active connections.
Performance
impact:
Variable
Limit replication transmitters and receivers and XLA
readers
Replication and XLA operations have significant logging overhead. Replication
scales best when there are a limited number of transmitters and/or receivers.
Check your replication topology and see if you can simplify it. XLA scales best
when there are a limited number of readers. If your application has numerous
readers, see if you can reduce the number.
Monitor XLA and replication to ensure they are reading from the log buffer
rather than from the disk. With a lot of concurrent updates, replication may not
keep up. Updates are single-threaded at the subscriber. You can achieve better
XLA throughput if the frequency of acknowledgements is reduced.
Estimate the number of readers and transmitters required by checking the values
in the LOG_FS_READS and LOG_BUFFER_WAITS columns in the
SYS.MONITOR table. The system updates this information each time a
connection is made or released and each time a transaction is committed or rolled
back.
Setting LogFlushMethod=2 can improve performance of RETURN TWOSAFE
replication operations and RETURN RECEIPT with DURABLE TRANSMIT
operations.
Performance
impact:
variable
Allow indexes to be rebuilt in parallel during recovery
On multi-processor systems, set RecoveryThreads to minimum(number of
CPUs available, number of indexes) to allow indexes to be rebuilt in parallel if
Data Store Performance Tuning 175
recovery is necessary. If a rebuild is necessary, progress can be viewed in the
daemon log. Setting RecoveryThreads to a number larger than the number of
CPUs available can cause recovery to take longer than if it were single-threaded.
Performance
impact:
variable
Use private commands
On multi-processor systems, if many threads are executing the same commands,
then try setting PrivateCommands=1 to improve throughput or response time.
The use of private commands increases the amount of temporary space used.
176 Oracle TimesTen In-Memory Database Operations Guide
XLA acknowledgement modes
Performance
impact:
medium
Prefetch multiple update records
Performance
impact:
medium
Acknowledge XLA updates
Prefetching multiple update records at a time is more efficient than obtaining
each update record from XLA individually. Because updates are not prefetched
when you use AUTO_ACKNOWLEDGE mode, it can be slower than the other
modes. If possible, you should design your application to tolerate duplicate
updates so you can use DUPS_OK_ACKNOWLEDGE, or explicitly
acknowledge updates. Explicitly acknowledging updates usually yields the best
performance if the application can tolerate not acknowledging each message
individually.
To explicitly acknowledge an XLA update, you call acknowledge on the update
message. Acknowledging a message implicitly acknowledges all previous
messages. Typically, you receive and process multiple update messages between
acknowledgements. If you are using the CLIENT_ACKNOWLEDGE mode and
intend to reuse a durable subscription in the future, you should call acknowledge
to reset the bookmark to the last-read position before exiting.
Data Store Performance Tuning 177
178 Oracle TimesTen In-Memory Database Operations Guide
9
The TimesTen Query Optimizer
The TimesTen cost-based query optimizer uses information about an
application’s tables and their available indexes to choose a fast path to the data.
Application developers can examine the plan chosen by the optimizer to check
that indexes are used appropriately. If necessary, application developers can also
modify the optimizer’s behavior so that it chooses a different plan.
This chapter includes the following topics:
• When optimization occurs
• Viewing a plan
• Modifying plan generation
179
When optimization occurs
It is useful to understand when TimesTen performs query optimization, since a
single command may be optimized several times.
TimesTen invokes the optimizer whenever a SELECT, UPDATE, DELETE,
INSERT SELECT or CREATE VIEW statement is prepared through an ODBC
SQLPrepare or SQLExecDirect function or any of the JDBC execute methods.
If SQLPrepare is used, the resulting plan persists until an invalidating event
occurs, or the command is dropped by the application. A command is invalidated
under the following circumstances:
• A table it uses is dropped
• A table it uses is altered
• An index on a table it references is dropped
• An index is created on a table it references
• Statistics are recomputed
An invalid command is usually reprepared automatically just before it is reexecuted. This means that the optimizer is invoked again at this time, possibly
resulting in a new plan. Thus, a single command may be prepared several times.
Note: When using JDBC, you must manually reprepare commands when a table
has been altered.
A command may have to be prepared manually if, for example, the table that the
command referenced was dropped and a new table with the same name was
created. When you prepare a statement manually, you should commit the prepare
statement so it can be shared. If the command is recompiled because it was
invalid, and if recompilation involves DDL on one of the referenced tables, then
the prepared statement must be committed to release the command lock.
For example, in ODBC a command joining tables T1 and T2 may undergo the
following changes:
SQLPrepare
Command is prepared.
SQLExecute
Command is executed.
SQLExecute
Command is re-executed.
.
.
.
Create Index on T1
Command is invalidated.
SQLExecute
Command is reprepared, then executed.
180 Oracle TimesTen In-Memory Database Operations Guide
SQLPrepare
Command is prepared.
SQLExecute
Command is re-executed.
.
.
.
ttOptUpdateStats on T1
Command is invalidated (if the
invalidate flag is passed to the
ttOptUpdateStats procedure).
.
.
.
SQLExecute
Command is reprepared, then executed.
SQLExecute
Command is re-executed.
.
.
.
SQLFreeStmt
Command is dropped.
In JDBC, a command joining tables T1 and T2 may undergo the following
changes:
Connection.prepareStatement
Command is prepared.
PreparedStatement.execute
Command is executed.
PreparedStatement.execute
Command is re-executed.
.
.
.
Create Index on T1
Command is invalidated.
PreparedStatement.execute
Command is reprepared, then
executed.
PreparedStatement.execute
Command is re-executed.
The TimesTen Query Optimizer 181
Connection.prepareStatement
Command is prepared.
.
.
.
ttOptUpdateStats on T1
Command is invalidated (if the
invalidate flag is passed to the
ttOptUpdateStats procedure).
.
.
.
PreparedStatement.execute
Command is reprepared, then
executed.
PreparedStatement.execute
Command is re-executed.
.
.
.
PreparedStatement.close
Command is dropped.
As illustrated, optimization is generally performed at prepare time, but it may
also be performed later when indexes are dropped or created, or when statistics
are modified. Optimization does not occur if a prepare can use a command in the
cache.
If a command was prepared with the genPlan flag set, it will be recompiled with
the same flag set. Thus, the plan is generated even though the plan for another
query was found in the SYS.PLAN table.
If an application specifies hints to modify the optimizer’s behavior (see
“Modifying plan generation” on page 187), these hints persist until the command
is deleted. (For example, when the ODBC SQLPrepare function or JDBC
Connection.prepareStatement method is called again on the same handle or
when the SQLFreeStmt function or PreparedStatement.close method is
called.) This means that any intermediate reprepare operations that occur because
of invalidations will use those same hints.
182 Oracle TimesTen In-Memory Database Operations Guide
Viewing a plan
Several steps are needed to view a plan for a prepared SELECT, UPDATE,
DELETE, INSERT SELECT or CREATE VIEW statement:
• Generating the plan involves instructing TimesTen to store the command’s
plan in the system PLAN table.
• Preparing the statement means calling the ODBC SQLPrepare function or
JDBC Connection.prepareStatement method on the statement.
• Reading the SYS.PLAN table is the final step.
After the first two steps have been completed, TimesTen places the
command’s plan in the PLAN table. The stored plan is then updated
automatically whenever the command is reprepared. This re-preparation is not
likely to occur often. However, if a table in the statement is altered, or if indexes
are created or dropped, or the application chooses to invalidate commands when
statistics are updated, it may help to read the PLAN table again to see if the
command’s plan has changed.
Generating the plan
Before you can view the plan, you must call the built-in procedure ttOptSetFlag
with the GenPlan flag. This call informs TimesTen that all subsequent calls to the
ODBC SQLPrepare function or JDBC Connection.prepareStatement method
in the transaction should store the resulting plan in the current SYS.PLAN table.
Note: Make sure AUTOCOMMIT is not set. If it is, the current transaction will
complete after the processing of the command and prepares in the next
transaction will not be affected.
The SYS.PLAN table only stores one plan, so each call to the ODBC
SQLPrepare function or JDBC Connection.prepareStatement method
overwrites any plan currently stored in the table.
If a command was prepared with the genPlan flag set, it will be recompiled with
the same flag set. Thus, the plan is generated even though the plan for another
query was found in the SYS.PLAN table.
For the purposes of experimentation, you can try query and optimizer hints using
the ttIsql utility. To display optimizer plans, issue the commands:
autocommit 0;
showplan 1;
Reading the PLAN table
Once plan generation has been turned on and a command has been prepared, one
or more rows in the SYS.PLAN table store the plan for the command. The
number of rows in the table depends on the complexity of the command. Each
The TimesTen Query Optimizer 183
row has seven columns, as described in the chapter “System and Replication
Tables” in the Oracle TimesTen In-Memory Database API and SQL Reference
Guide.
Example 9.1
A Query and
its plan
Assume you prepare the following query:
SELECT COUNT(*)
FROM T1, T2, T3
WHERE T3.B/T1.B > 1
AND T2.B <> 0
AND T1.A = -T2.A
AND T2.A = T3.A
The optimizer may generate the five SYS.PLAN rows shown in the following
table. Each row is one step in the plan and reflects an operation that is performed
during query execution.
Step
Level
Operations
Tbl
Names
IXName
1
3
TblLkTtreeScan
T1
IX1
2
3
TblLkTtreeScan
T2
IX2(D)
3
2
MergeJoin
4
2
TblLkTtreeScan
5
1
MergeJoin
Pred
Other Pred
T2.B <> 0
T1.A = –T2.A
T3
IX3(D)
T2.A = T3.A
T3.B / T1.B > 1
The remainder of this section provides detailed information about each column in
the SYS.PLAN table, using Example 9.1 throughout.
184 Oracle TimesTen In-Memory Database Operations Guide
PLAN table columns
The SYS.PLAN table has seven columns. They are described in this section.
Column 1
(Step)
Indicates the order of operation. This example uses a table lock T-tree scan. The
order is:
1.
Table locking T-tree scan of IX1 on table T1.
2.
Table locking T-tree scan of IX2 on T2.
3.
Merge join of T1 and T2 and so forth.
The steps always start with 1.
Column 2
(Level)
Indicates the position of the operation in the join-tree diagram that describes the
execution. For the example above, the join tree looks like:
MergeJoin (Step 5)
MergeJoin (Step 3)
TblLkTtreeScan (Step 1)
Column 3
(Operation)
TblLkTtreeScan (Step 4)
TtreeScan (Step 2)
Level 1
Level 2
Level 3
Indicates the type of operation being executed. For a description of the values in
this field and the type of table scan each represents, see SYS.PLAN in the
chapter “System and Replication Tables” in the Oracle TimesTen In-Memory
Database API and SQL Reference Guide.
Not all operations the optimizer performs are visible to the user. Only operations
significant to performance analysis are shown in the SYS.PLAN table. TblLk is
an optimizer hint that is honored at execution time in serializable or readcommitted isolation. Table locks are used during a scan only if row locks are
disabled during preparation.
Column 4
(TblNames)
Column 5
(IXName)
Indicates the table that is being scanned. This column is used only when the
operation is a scan (one of the first five operations listed above). In all other
cases, this column is NULL.
Indicates the index that is being used. This column is used only when the
operation is an index scan using an existing index (using a hash or T-tree scan). In
all other cases, this column is NULL. Names of T-tree indexes are followed with
The TimesTen Query Optimizer 185
“(D)” if the scan is descending (from large to small rather than from small to
large).
Column 6
(Pred)
Indicates the predicate that participates in the operation, if there is one. Predicates
are used only with index scan and MergeJoin operations.
This column may be NULL (no predicate) for a T-tree scan. The optimizer may
choose a T-tree scan over a table scan because it has two useful properties in
addition to filtering:
• Rows are returned in sorted order (on index key).
• Rows may be returned faster (especially if the table is sparse).
In Example 9.1, the T-tree scans are used for their sorting capability; none of
them evaluates a predicate.
The predicate character string is limited to 1,024 characters.
Column 7
(Other
Pred)
Indicates any other predicate that is applied while the operation is being
executed. These predicates do not participate directly in the scan or join but are
evaluated on each row returned by the scan or join.
For example, at step 2 of the plan generated for the example above, a T-tree scan
is performed on table T2. When that scan is performed, the predicate T2.B <> 0
is also evaluated. Similarly, once the final merge-join has been performed, it is
then possible to evaluate the predicate T3.B / T1.B > 1.
186 Oracle TimesTen In-Memory Database Operations Guide
Modifying plan generation
This section explains why you may want to modify execution plans and then
describes how to modify them.
Why modify an execution plan?
Applications may want to modify an execution plan for two reasons:
• The plan is optimally fast but is ill-suited for the application. The optimizer
may select the fastest execution path, but this path may not be desirable from
the application’s point of view. For example, if the optimizer chooses to use
certain indexes, these choices may prevent other operations—such as certain
update or delete operations—from occurring simultaneously on the indexed
tables. In this case, an application can prevent the use of those indexes.
The plan chosen by the optimizer may also consume more memory than is
available or than the application wants to allocate. For example, this may
happen if the plan stores intermediate results or requires the creation of
temporary indexes.
• The plan is not optimally fast. The query optimizer chooses the plan that it
estimates will execute fastest based on its knowledge of the tables’ contents,
available indexes, statistics and the relative costs of various internal
operations. The optimizer often has to make estimates or generalizations when
evaluating this information, so there can be instances where it does not choose
the fastest plan. In this case, an application can adjust the optimizer’s behavior
to try to produce a better plan.
When to modify an execution plan
Applications can modify an execution plan by giving hints to the optimizer. Hints
are specified by calls to one of the TimesTen optimizer built-in procedures (see
“How to modify execution plan generation” on page 192) and are in effect for all
calls to the ODBC SQLPrepare function or JDBC PreparedStatement objects
in the transaction.
Note: Make sure AUTOCOMMIT is not set. If it is, the current transaction will
complete after processing the ttOptSetFlag procedure and prepares in the next
transaction will not be affected.
If a command is prepared with certain hints in effect, those hints continue to
apply if the command is reprepared automatically, even when this happens
outside the initial prepare’s transaction. This can happen when a table is altered,
or an index is dropped or created, or when statistics are modified, as described in
“When optimization occurs” on page 180.
The TimesTen Query Optimizer 187
If a command is prepared without hints, subsequent hints will not affect the
command if it is reprepared automatically. An application must call the ODBC
SQLPrepare function or JDBC Connection.prepareStatement method a
second time so that hints have an effect.
Example 9.2
When using ODBC, a developer tuning a join on T1 and T2 might go through the
following steps:
Put plans into the PLAN table
ttOptSetFlag
Prepare command
SQLPrepare
Examine PLAN table
SELECT * FROM
SYS.PLAN
Set various optimizer hints
ttOptSetFlag
Prepare command again
SQLPrepare
Examine PLAN table...
SELECT * FROM
SYS.PLAN
Fully optimized!
188 Oracle TimesTen In-Memory Database Operations Guide
During execution, the application may then go through the following steps (with
no user intervention):
Set various optimizer hints.
ttOptSetFlag
Prepare command.
SQLPrepare
Execute command.
SQLExecute
Execute command.
SQLExecute
Command is invalidated
(if application chooses to invalidate).
ttOptUpdateStats
on T2
Command is reprepared automatically,
using same hints, and executed.
SQLExecute
Execute command.
SQLExecute
Drop command.
SQLFreeStmt
The TimesTen Query Optimizer 189
Example 9.3
When using JDBC, a developer tuning a join on T1 and T2 might go through the
following steps:
Put plans into the PLAN table
ttOptSetFlag
Prepare command
Connection.prepareStatement
Examine PLAN table
SELECT * FROM
SYS.PLAN
Set various optimizer hints
ttOptSetFlag
Prepare command again
Connection.prepareStatement
Examine PLAN table...
SELECT * FROM
SYS.PLAN
Fully optimized!
190 Oracle TimesTen In-Memory Database Operations Guide
During execution, the application may then go through the following steps (with
no user intervention):
Set various optimizer hints.
ttOptSetFlag
Prepare command.
Connection.prepareStatement
Execute command.
Statement*.execute*
Execute command.
Statement*.execute*
Command is invalidated
(if application chooses to invalidate).
ttOptUpdateStats on T2
Command is re-prepared automatically,
using same hints, and executed.
Statement*.execute*
Execute command.
Statement*.execute*
Drop command.
PreparedStatement.close
The TimesTen Query Optimizer 191
How to modify execution plan generation
To change the query optimizer behavior, an application calls one of the following
built-in procedures using the ODBC procedure call interface:
• ttOptClearStats
• ttOptEstimateStats
• ttOptSetColIntvlStats
• ttOptSetFlag
• ttOptSetOrder
• ttOptSetTblStats
• ttOptUpdateStats
• ttOptUseIndex
The procedure ttOptSetFlag sets certain optimizer parameters. ttOptSetOrder
allows an application to specify the table join order. The procedure
ttOptUseIndex allows an application to disable the use of certain indexes. The
remaining procedures manipulate statistics the TimesTen Data Manager
maintains on the application’s data that are used by the query optimizer to
estimate costs of various operations. See the Chapter 3, “Built-In Procedures” in
the Oracle TimesTen In-Memory Database API and SQL Reference Guide.
Example 9.4 shows an ODBC example of how to use ttOptSetFlag. Example 9.5
shows a JDBC example.
Example 9.4
The ODBC example below illustrates the use of ttOptSetFlag to prevent the
optimizer from choosing a merge join.
import java.sql.*;
class Example
{
public void myMethod() {
CallableStatement cStmt;
PreparedStatement pStmt;
. . . . .
try {
. . . . . . .
// Prevent the optimizer from choosing Merge Join
cStmt = con.prepareCall("{
CALL ttOptSetFlag('MergeJoin', 0)}");
cStmt.execute();
192 Oracle TimesTen In-Memory Database Operations Guide
// Next prepared query
pStmt=con.prepareStatement(
"SELECT * FROM Tbl1, Tbl2 WHERE Tbl1.ssn=Tbl2.ssn");
. . . . . . .
catch (SQLException ex) {
ex.printStackTrace();
}
}
. . . . . . .
}
Example 9.5
The JDBC example below illustrates the use of ttOptSetFlag to prevent the
optimizer from choosing a merge join.
#include <sql.h>
SQLRETURN rc;
SQLHSTMT hstmt; fetchStmt;
....
rc = SQLExecDirect (hstmt, (SQLCHAR *)
"{CALL ttOptSetFlag (MergeJoin, 0)}",
SQL_NTS)
/* check return value */
...
rc = SQLPrepare (fetchStmt, ...)
/* check return value */
...
You can also experiment with optimizer settings using the ttIsql utility. The
commands that start with try control the optimizer hints. To view the current
optimizer hint settings, use the optprofile command.
The TimesTen Query Optimizer 193
194 Oracle TimesTen In-Memory Database Operations Guide
10
UNIX Configuration Files
This chapter provides supplemental information about the UNIX configuration
files:
• Working with the ODBC.INI file
• Working with the TTCONNECT.INI file
195
Working with the ODBC.INI file
This section includes the following topics:
• The user ODBC.INI file
• The system ODBC.INI file
• Searching for a DSN
• ODBC Data Sources
• Data Source Specification
• odbc.ini file example
The user ODBC.INI file
On UNIX, user DSNs are defined in the file $HOME/.odbc.ini or in a file named
by the ODBCINI environment variable. This file is referred to as the “user
ODBC.INI file.” Although a user DSN is private to the user who created it, it is
only the DSN (the character-string name and its attributes) that is private. The
underlying data store can be referenced by other user DSNs or by system DSNs.
TimesTen supports data sources for the TimesTen Data Manager and data sources
for the TimesTen Client in the .odbc.ini file.
For information on how to create a copy of the .odbc.ini file in your home
directory and how to override the name and location of the .odbc.ini file, see
“Data source names” on page 33.
The system ODBC.INI file
On UNIX, system DSNs are defined in the /var/TimesTen/sys.odbc.ini file.
This file is referred to as the “system ODBC.INI file.” A system DSN can be
used by any user on the machine on which the system DSN is defined.
Searching for a DSN
See “Searching for a DSN” on page 67 for the rules of precedence that TimesTen
follows when searching for a DSN.
ODBC Data Sources
Each entry in the optional ODBC Data Sources section lists a data source and a
description of the driver it uses. The data source section has the format:
[ODBC Data Sources]
data-source-name=driver-description
The data-source-name is required. It identifies the
data source to which the driver connects. You
choose this name.
The driver-description is required. It describes the
driver which connects to the data source.
196 Oracle TimesTen In-Memory Database Operations Guide
Data Source Specification
Each data source listed in the ODBC Data Sources section has its own data
source specification section. The data store specification for TimesTen Data
Manager data stores has the format:
The data-source-name is required. It is the name of the data source, as
specified in the ODBC Data Sources section of your .odbc.ini file.
[data-source-name]
Driver=driver path name
DataStore=data store path name
optional attributes
The TimesTen Data Manager driver that is linked with
the data source.
The path name of the data store to access. Required.
See “Data store attributes”
information on attributes.
on page 19 for
For example, a data source called RunData may have the following data source
specification entry:
[RunData]
Driver=install_dir/lib/libtten.sl
DataStore=/users/robin/SalesDs
#create data store if it’s not found
AutoCreate=1
#do not wait if cannot connect to data store
WaitForConnect=0
#remove old log files at connect and checkpoint
LogPurge=1
The data store specification for TimesTen Client configurations has the format:
The data-source-name is required. It is the name of the data source, as
specified in the ODBC Data Sources section of your .odbc.ini file.
[data-source-name]
TTC_Server=server-name
TTC_Server_DSN=server-DSN
TTC_Timeout=value
The server-name is required. It is the DNS name, host name,
IP-address or shorthand name for the TimesTen Server.
The server-DSN is required. It is the name of the data source
to access on the TimesTen Server.
Note: Most TimesTen Data Manager attributes are ignored for TimesTen Client
data stores.
For example, the data source called RunDataCS that connects to the data source,
named RunData, on the ttserver TimesTen Server may have the data source
specification entry:
UNIX Configuration Files 197
[RunDataCS]
TTC_Server=ttserver
TTC_Server_DSN=RunData
TTC_Timeout=30
For example, the data source called ShmRunDataCS that uses a shared memory
segment to connect to the data source named RunData on the ShmHost60
TimesTen Server may have the data source specification entry:
[ShmRunDataCS]
TTC_Server=ShmHost60
TTC_Server_DSN=RunData
TTC_Timeout=30
odbc.ini file example
The following example shows a UNIX .odbc.ini file:
[ODBC Data Sources]
RunData_giraffe=TimesTen 6.0 Driver
RunDataCS_giraffe=TimesTen Client 6.0
[RunDataCS_giraffe]
TTC_Server=tt_server_logical
TTC_Server_DSN=RunData
TTC_Timeout=30
[RunData_giraffe]
Driver=install_dir/lib/libtten.sl
DataStore=/users/robin/RunData
PermSize=8
Exclusive=0
Logging=1
ThreadSafe=1
198 Oracle TimesTen In-Memory Database Operations Guide
Working with the TTCONNECT.INI file
TimesTen uses theTTCONNECT.INI file to define the names and attributes for
servers and the mappings between logical server names and their network
addresses. This information is stored on machine where the TimesTen Client is
installed. By default, the TTCONNECT.INI file is
/var/TimesTen/sys.ttconnect.ini.
To override the name and location of this file at runtime, set the
SYSTTCONNECTINI environment variable to the name and location of the
TTCONNECT.INI file before launching the TimesTen application.
Defining a server name on UNIX
You can define short-hand names for TimesTen Servers on UNIX in the
TTCONNECT.INI file. The format of a TimesTen Server specification in the
TTCONNECT.INI file is:
The short-hand name of the TimesTen
Server you wish to define.
[ServerName]
Description=description
Network_Address=network-address
TCP_Port=TCP/IP-port-number
The description of the TimesTen Server.
The DNS name, host name or IP address of the
machine on which the TimesTen Server is running.
The TCP/IP port number where the TimesTen Server
is running. Default for TimesTen release 6.0 is 16002
for 32-bit platforms and 16003 for 64-bit platforms.
For example, the server specification for a remote TimesTen Server might appear
as:
[ttserver]
Description=TimesTen Client/Server
Network_Address=server.company.com
TCP_Port=16002
For a local TimesTen Client/Server application that is using UNIX domain
sockets, the network address must be defined as ttLocalHost. The server
specification might appear as:
[LocalHost60]
Description=Shm TimesTen Client/Server
Network_Address=localhost
TCP_Port=16002
For a TimesTen Client/Server application that is using a shared memory segment
for inter-process communication, the network address must be defined as
ttShmHost. The server specification might appear as:
[ShmHost60]
Description=Shm TimesTen Client/Server
Network_Address=shmhost.company.com
UNIX Configuration Files 199
TCP_Port=16002
200 Oracle TimesTen In-Memory Database Operations Guide
Index
.odbc.ini 196
A
acknowledging updates 177
adding columns 120
adding rows 120
adding rows to a table 50
ALTER 171
ALTER TABLE
adding and removing columns 120
and performance 171
application failure
use of logs and locks 141
ASCII 16
asynchronous checkpoints See fuzzy checkpoints
attributes
and data source name 43
PermWarnThreshold 47
setting for UNIX 41
specifying 38
TempWarnThreshold 47
Auto Create 11, 13
AUTO_ACKNOWLEDGE mode 177
autocommit ttIsql command 98
automatic
checkpointing 155
index creation 121
B
background reading 3
backing up a data store 50
batch mode
ttIsql 90
C
cachegroups ttIsql command 100
changing shared memory segment size 86
checkpoints
automatic 119, 155
fuzzy 154
influences on duration 153
static 154
Client 199
Client connection attributes
described 58
Client DSN
creating 67
creating on UNIX 69
creating on Windows 60
Data Source Setup dialog 61
name 61
Client performance
TT_PREFETCH_CLOSE option 165
Client/Server
changing shared memory segment size 86
configuring 56
managing shared memory segment size 85
problems 73
Client/Server communication
shared memory 85
TCP/IP 85
client/server communication
overview 55
TCP/IP 55
UNIX socket 55
CLIENT_ACKNOWLEDGE mode 177
close ttIsql command 108
code font 4
coexistence of different locking levels 152
column values
default 121
columns
in-line 120
nullability 120
command history
ttIsql 96
commit ttIsql command 98
commitdurable ttIsql command 98
components of data store 118
concepts
exclusive and shared connections 36
concurrency
and logging 148
types of isolation 150
concurrent connections
maximum for Server 74
configuring
Client/Server 56
Index
Symbols
201
Connection.commit method 141
Connection.prepareStatement method 180, 183
and execution plan generation 188
Connection.rollback method 141
Connection.setAutoCommit method 141
connections
exclusive and shared 36
maximum number on Windows XP 75
performance overhead 161
problems, Server 73
testing on Windows 65
controlling logging 148
controlling Server log messages 87
controlling the TimesTen Server daemon 84
controlling web server options 88
copying a data store 50
CREATE INDEX statement 135
CREATE TABLE statement 14
creating a Client DSN
on UNIX 69
on Windows 60
creating a logical server name on UNIX 67
creating a Server
name 59
creating a Server DSN 58
creating indexes
example 135
explicit creation 121
how to do 135
creating tables
example 123, 125
Custom setup, Windows 31
D
daemon
control operations 82
informational messages on Windows 81
overview 77
starting and stopping on UNIX 79
starting and stopping on Windows 78
daemon startup script 79
data
permanent 46
temporary 46
Data Manager Service 78
data source
specification 197
UNIX configuration file 199
ttconnect.ini, format of 199
202
UNIX configuration files 198
Data Source Name. See DSN
data source names, See DSN
data store
accessing on a local machine 55
accessing on a remote machine 55
and data sources 10
backing up 50
backup 24
changing size of 46
components 118
connecting 13
copying 50
definition 29
destroying 25
getting information with ttIsql 100
migrating 50
path and name 11
path names, environment variables in 41
permanent 119
prefix name 41
restoring 26, 50
setting attributes for UNIX 41
sizing 160
TCP/IP client/server access 55
temporary 42, 119, 161
diskless operations 82
UID connection attribute 118
UNIX socket client/server access 55
user names 118
users and owners 118
working with 19
data store-level locking 151
default column values 121
DELETE statement 23, 24
deleting
rows 137
Windows server name 63
describe command 14, 16
describe ttIsql command 100, 108
destroying
indexes 135
tables, example 123, 129
detail table 124
diskless operations 49, 82
driver
JDBC 37
driver manager
JDBC 32
Oracle TimesTen In-Memory Database Operations Guide
linking with 30
ODBC 30
DRIVER parameter 40
DriverManager.getConnection 58
DriverManager.getConnection method
methods 58
DSN 10
.odbc.ini file 196
Client 34
connection attributes, Data Manager 35
Data Manager 34
defining 10
description of types 35
example, Windows
examples 42
finding in order of precedence 67
maximum length 33
naming rules 33
setting attributes 43
system 33
user 33
dssize ttIsql command 100
DUPS_OK_ACKNOWLEDGE mode 177
durability
overview 143
Durable Commits 12
E
editline for ttIsql 94
environment variables
in data store path names 41
TTISQL 112
estimating
data store size 160
index size 135
table size 123
examples
creating indexes 135
creating tables 123, 125
destroying tables 123, 129
PLAN rows 184
exclusive and shared connections 36
exec ttIsql command 108
execandfetch ttIsql command 108
execution plan
generating 180, 188
modifying 187, 192
viewing 183
execution plan generation
and Connection.prepareStatement 188
F
failures
Server 74
fetchall ttIsql command 108
fetchone ttIsql command 108
files
.ttconnect.ini 199
odbc.ini 196, 198
ttconnect.ini 199
ttendaemon.options 80, 82, 85
UNIX configuration 195
foreign key constraint
and performance 170
fragmentation
block-level 160
free ttIsql command 108
fuzzy checkpoints, definition 154
G
Groff, James R. 4
GROUP BY clause 21
H
Hamilton, Cattell, Fisher 3
hash indexes
definition 133
sizing 170
vs. T-tree indexes 169
when used 133
Horstmann, Cornell 3
I
index size
estimating 135
ttSize utility 135
indexes
and performance 168
automatic creation 121
creating 121, 135
destroying 135
overview 133
owner 135
referencing 135
See also T-tree indexes
See also hash indexes
unique 133
Index 203
informational messages
modifying 81
in-line columns 120
INSERT statement 19
inserting rows 137
installation
default directory 4
interactive mode
ttIsql 90
invalidating commands 180
isolation modes
described 150
SERIALIZABLE 150
isolation ttIsql command 98
italic font 4
IXNAME column in PLAN table 185
J
Java
reference reading 3
JDBC
driver 32
driver manager 32
reference reading 3
JDBC tracing 162
join
columns, view performance 172
rows, view performance 172
L
LEVEL column in PLAN table 185
linking applications
Client/Server 53
direct 30
UNIX 30
Windows 30
with driver manager 30
loading a data store to memory 48
locale 115
locking
See also locks
See also ttLockLevel
locks
coexistence of different levels 152
overview table 140
Log Files 11
log files
names 149
204
logging
attribute for concurrent connections 148
how to control 148
overview table 140
temporary data store 119
logical server
Network Address 55, 59, 67
logical server name
creating on UNIX 67
M
maintenance options
performance impact 162
managing shared memory segment size 85
materialized views, see ’views’
maximum
concurrent Server connections 74
maximum name length 121
Melton, Jim 3
memory
and performance 160
loading a data store into 48
partitions 46
permanent 46
policy for loading a data store 48
temporary 46
messages
informational 57
modifying on UNIX 82
server log 57
metadata, TimesTen 122
methods
Connection.commit 141
Connection.prepareStatement 183
Connection.rollback 141
Connection.setAutoCommit 141
migrating data stores 50
modes
diskless 82
modifying execution plan
overview 187
procedure overview 192
modifying informational messages 81
modifying Server daemon options 84
modifying UNIX informational messages 82
modifying web server options 88
monitor ttIsql command 100
multi-processor optimizations 160
Oracle TimesTen In-Memory Database Operations Guide
N
names
log files 149
maximum 121
naming a Client DSN 61
nested subqueries
and performance 171
Network Address for logical server
ttLocalHost 55
ttShmHost 55
UNIX 67
Windows 59
non-materialized view
creating 131
nonmaterialized view
description 130
non-materialized views 131
dropping or destroying 132
restrictions 132
SELECT query 131
not inline columns 120
NULL values, sorting 133
nullable columns
definition 120
primary key not nullable 122
O
ODBC 10
tracing and performance 162
UNIX driver 40
ODBC functions
and the JDBC driver 32
odbc.ini 196
entry example 198
format of 198
online help 92
OPERATION column in PLAN table 185
optimizer
application hints 182
example scenario 180, 181
generating plan 183
invalid statistics 180
modifying execution plan 187
PLAN row example 184
reading plan 183
viewing plans 183
optprofile ttIsql command 103
ORDER BY clause 21
OS paging 162
OTHERPRED column in PLAN table 186
outer join
materialized view performance 173
out-of-memory warnings 47
owners
of indexes 135
P
performance
and altered tables 171
and autocommit 141
and foreign key constraints 170
and thread safety 161
application tuning
connection overhead 161
maintenance options 162
ODBC tracing 162
automatic index creation 121
Client 164
data store tuning
and memory 160
driver usage 162
specifying size 160
temporary vs. permanent data store 161
join columns in materialized views 172
join rows in materialized views 172
materialized views 173
SELECT statement 165
SQL tuning
indexes 168
TT_PREFETCH_CLOSE option 165
tuning 159
working locally 164
permanent data partition 46
permanent data store 119
automatic checkpointing 119
PermWarnThreshold attribute 47
PLAN rows 184
plan See execution plan 185
PLAN table
columns 185
IXNAME column 185
LEVEL column 185
OPERATION column 185
OTHERPRED column 186
PRED column 186
STEP column 185
TBLNAME column 185
Index 205
PRED column in PLAN table 186
limit on length 186
prefetch multiple update records 177
prepare ttIsql command 108
PreparedStatement objects 187
preparing statements 183
primary keys 122
nullability 122
See Also unique indexes
problems
Client/Server 73
Q
query optimizer
See optimizer
query optimizer plans 180
viewing with ttIsql 103
R
RAM policy
defined 48
referencing indexes 135
remote data store
accessing on UNIX 67, 69, 70, 71
accessing on Windows 64
removing
columns 120
rows 120
replication
and TimesTen daemon 77
diskless 49
temporary data partition 47
TTREP system tables 121
restoring a data store 50
restrictions on table names 121
rollback
logs and locks 140
rollback ttIsql command 98
row-level locking 151
rows
deleting 137
in-line and out-of-line portions 120
inserting 137
understanding 136
S
Sanders, Roger E 3
SELECT statement 17, 20, 21
206
SELECT statement performance 165
SERIALIZABLE isolation mode 150
Server
connection problems 73
controlling the daemon 84
creating a DSN 58
described 57
failures 74
modifying daemon 84
name 61, 63
Server List dialog 59
Server Name Setup dialog 59
shorthand name 199
starting and stopping 57
Server log messages 87
server name
creating on Windows 59
serverShmIpc 85
serverShmSize 86
Service, See daemon
setjoinorder ttIsql command 103
setting data store attributes
UNIX 41
setting the timeout interval on Windows 62
setuseindex ttIsql command 103
shared and exclusive connections 36
shared data store
durable and nondurable connections 148
shared memory
Client/Server IPC 85
Client/Server, changing size 86
Client/Server, managing size 85
shared memory IPC-enabled server 85
shorthand names for servers 199
showplan command 103, 110
Signore, Robert 3
Simon, Alan R 3
Siple, Mathew 3
size
data store 46
sizing
data stores 160
hash indexes 170
sorting NULL values 133
specifying data store size 160
SQL 14
reference reading 3
tuning and performance 168
SQLPrepare 180, 183
Oracle TimesTen In-Memory Database Operations Guide
and execution plan generation 188
sqlquerytimeout ttIsql command 98
SQLTransact
undoing effects 141
starting and stopping the Server 57
starting and stopping the TimesTen Data Manager
78
starting the daemon
on UNIX 79
on Windows 78
starting the Data Manager Service 78
static checkpoints, definition 154
statistics
computing 170
recomputation 180
ttOptEstimateStats 170
ttOptUpdateStats 170
Stegman, Michael O. 3
STEP column in PLAN table 185
stopping the daemon
on UNIX 79
on Windows 78
stopping the Data Manager Service 78
subdaemons
minimum required 82
setting allowable number 82
specifying allowable range 82
synchronous checkpoints See static checkpoints
SYS owner of tables 121
syslog 82
System DSN 37, 63, 65
system failure
resulting logs and locks 141
system tables
indexes on 135
overview 122
T
table size
estimating 123
ttSize utility 123
Tables
creating 14
populating 16
tables
adding rows 50
creating, example 123, 125
deleting rows 137
destroying, example 123, 129
format 120
in-line vs. not inline columns 120
inserting rows 137
modifying format 120
name length 121
names 121
names, restrictions 121
nullable columns 120
owners 121
SYS owner 121
understanding rows 136
unique indexes 122
TBLNAME column in PLAN table 185
TCP/IP client/server communication 55
Temporary attribute
performance 161
temporary data partition
and replication 47
temporary data store
logging 119
TempWarnThreshold attribute 47
testing connections on Windows 65
thread programming
and TimesTen 36
ThreadSafe attribute
performance 161
timeout interval
setting on Windows 62
TimesTen
installing 4
ODBC driver 30
thread programming 36
TimesTen Server daemon 84
timestend 77
timing ODBC function calls 107
transaction commit
logs and locks 140
transaction management
isolation levels 139
locking 140
logging 140
semantics 140
transaction rollback
logs and locks 140
troubleshooting
Client/Server 73
Server connections 73
Server failures 74
tryhash ttIsql command 103
Index 207
trymergejoin ttIsql command 103
trynestedloopjoin ttIsql command 103
tryrowid ttIsql command 103
tryserial ttIsql command 103
trytbllocks ttIsql command 103
trytmphash ttIsql command 103
trytmptable ttIsql command 103
trytmpttree ttIsql command 103
tryttree ttIsql command 103
TT_PREFETCH_CLOSE 165
ttBackup 24
ttBulkCp 16
ttconnect.ini file 199
ttDaemonAdmin utility 86
ttDestroy 25
ttendaemon.options file 80, 81, 82, 85
ttIsql 13, 92
built-in command usage 98, 100, 101, 106,
107, 108
command history 96
deleting rows 137
displaying data store information 100
editline feature 94
modes, interactive and batch 90
online help 92
timing ODBC function calls 107
using 89
viewing optimizer plan 103
working with parameterized SQL statements
108
working with prepared SQL statements 108
working with transactions 98
TTISQL environment variable 112
ttLocalHost
logical server address 55
ttOptEstimateStats
statistics computing 170
T-tree indexes
vs. hash indexes 169
TTREP system tables 121
ttRestore 24, 26
ttShmHost 199
logical server address 55
ttStatus 25
ttWarnOnLowMemory procedure 47
typographical conventions 4
U
Unicode
208
locale-based output 115
reference reading 4
Unicode Consortium 4
working with in ttIsql 115
unique indexes 122, 133
See also primary key
UNIX
setting attributes 41
UNIX configuration file
odbc.ini 198
UNIX configuration files
.odbc.ini, format of 198
odbc.ini 195
ttconnect.ini 195
ttconnect.ini, format of 199
UNIX socket client/server communication 55
unsetjoinorder ttIsql command 103
unsetuseindex ttIsql command 103
UPDATE statement 22
updates
materialized view performance 172
using shared memory for Client/Server IPC 85
utilities
ttDaemonAdmin 86
V
VALUES clause 19
view
creating 131
description 130
viewing query optimizer plans 183
views
creating 125
dropping 129
dropping or destroying 132
non-materialized 131
performance 127
restrictions 132
restrictions on detail tables 126
restrictions on view tables 126
SELECT queries in 125
SELECT query for non-materialized 131
understanding 124
W
web server options
modifying 88
Weinberg, Paul N. 4
Oracle TimesTen In-Memory Database Operations Guide
WHERE clause 20, 21, 24
working with
parameterized SQL statements 108
prepared SQL statements 108
X
XLA bookmark, deleting 114
XLA updates
acknowledging 177
xladeletebookmark ttIsql command 114
Index 209
210
Oracle TimesTen In-Memory Database Operations Guide
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