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SQL Optimizer for DB2 LUW 4.3.1 - User Guide

SQL Optimizer for IBM® DB2® LUW
About SQL Optimizer for IBM DB2 LUW Getting Started Options SQL Scanner SQL Optimizer SQL Formatter SQL Inspector Database Explorer SQL Repository Index Impact Analyzer Index Usage Analyzer User-Defined Temp Table Editor Functions SQL Functions SQL Information and Functions Activity Log
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New Analysis Wizard: Analyzer Page

In the Analyzer page, you can select to create an new Analyzer or to use an existing Analyzer with the SQL statements that are already in the SQL Repository for that Analyzer.

Select a new or existing Analyzer

Create a new Analyzer and select SQL to analyze

Specify to create an new Analyzer and to then select the SQL statements from the SQL Repository that you want to use in this new Analyzer.

Continue an existing Analyzer using the Analyzer's selected SQL

Specify to use an Analyzer that you have previously created with the SQL statements that are already stored with that Analyzer.

Analyzer Information




If you are creating a new Analyzer, enter a name.

If you are using an existing Analyzer, select the from the Select Analyzer box.


If you are creating a new Analyzer, enter the description for the analysis.

Last modified

Displays the last modified date and time.

Save location

Displays the folder in the tree where the Analyzer is saved. In the bottom pane, select the folder where you want to save the Analyzer. To create a new folder, click image\B_AddFolder.gif.


New Analysis Wizard: Select SQL Page

In the New Analysis wizard, the Select SQL page is used to select the SQL statements whose access plans you want to analyze in order to review the impact on their performance that the creation of new indexes would have.

Select SQL to check for performance changes

Select SQL from:

The SQL statements used in an analysis can be taken from the SQL Repository or the SQL Scanner. If you select SQL statements from the SQL Scanner, these statements are added to the SQL Repository.

Select the SQL statements for the analysis. If you select SQL statements from the SQL Scanner, the bottom portion of this section displays the SQL Repository folder so that you can select the folder where they will be stored.

SQL access plans to be analyzed

In order to analyze the impact the proposed indexes might have on the performance of the SQL statements, the Index Impact Analyzer compares the query before the indexes are created to the plans after the indexes are created. The access plans from before the analysis can be obtained two ways:

Using existing access plan saved with the SQL

This option uses the access plan that was saved with the SQL statement when it was saved in the SQL Repository or SQL Scanner.

Obtaining a new access plan under the current connection

This option retrieves the access plan with the current logon and the current database settings. This current access plan is compared to the access plan that is retrieved after the new indexes are created.


New Analysis Wizard: Index Page

In the New Analysis wizard, the Index page is used to specify the index(es) that are used for this analysis.

Access plans will be grouped under a Scenario

An individual Index Impact Analyzer consists of a group of stored SQL statements with the access plans called the " Baseline." The actual Impact Analysis is displayed in a "Scenario." A Scenario shows the comparison information for the stored SQL statements identifying the impact on the access plan that the creation of new index will have.




Enter a name for the Scenario.


Enter a description.

Add Index

Click image\B_AddIndex.gif.



Index Name

Enter a name for the index.


Select a name for the index.


Select a table for the index.

Table columns

Double-click one or more columns.

Index type: Unique, Clustered, Allow Reverse Scans

Select the type of index.


Remove Index

Click image\B_RemoveIndex.gif.

After you have created the first Scenario, you can add more Scenarios.


Add Index Window

The Add Index window is used to create the DDL for creating of the indexes for the Index Impact Analysis.



Index name

Enter a name for the index. By default, the prefix of the index name is taken from the Index Expert settings in the Options window and then a random number is generated for the rest of the index name.

Note: It is best not to change the prefix for the index. The indexes are generated as virtual indexes. If the Impact Analysis process terminates abnormally and a virtual index is left on the database, it can be easily identified as a virtual index which was created by SQL Optimizer by the prefix.


Select the database where the index is to be created from the database list.


Select the owner of the index from the drop-down list.


Select the table where the index is to be created from the drop-down list.

Table columns

List of all the columns from the selected table.

Index columns

Move the columns to be indexed from the Table columns list by highlighting the column and clicking image\B_AddDatabaseObjects.gif.


Specify to create a unique index.


Select to create either a clustered or a nonclustered index.


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