About Index Impact Analyzer
The Index Impact Analyzer analyzes the performance impact of new indexes on SQL statements before the indexes are permanently created on your database. New indexes may improve the performance of one SQL but downgrade the performance of several others. The Index Impact Analyzer evaluates the performance effect that given indexes might have on SQL statements, thereby removing the uncertainty associated with index creation.
The Index Impact Analyzer analyzes the performance impact of index creation on SQL statements retrieved from the SQL Repository or the SQL Scanner. To analyze the impact that creating new indexes might have on SQL performance, the proposed indexes are created as virtual indexes on the database. Then new access plans are retrieved showing the impact the new indexes would on the access plans of individual SQL statements. The virtual indexes are dropped after the retrieval of the access plans.
After the analysis is complete, the Index Impact Analyzer provides metrics of the overall performance changes and allows you to identify which SQL statements have changes to access plan with the proposed indexes.
Index Impact Analyzer Window
Quest SQL Optimizer for IBM® DB2® LUW maximizes SQL performance by automating the manual, time-intensive and uncertain process of ensuring that SQL statements are performing as fast as possible. SQL Optimizer analyzes, rewrites, and evaluates SQL statements within multiple database objects, files, or SQL statements captured by the DB2 Event Monitor. With SQL Optimizer, you can analyze and optimize all your problem SQL from multiple sources. SQL Optimizer also provides you a complete index optimization and plan change analysis solution, from index recommendations to simulated index impact analysis, through comparison of multiple SQL access plans.
SQL Optimizer provides you with the following main modules.
SQL Optimizer (including SQL Rewrite and Generate Indexes functions)
Index Impact Analyzer Window
The Index Impact Analyzer window displays the information about the SQL statements that are saved in the Index Impact Analyzer. The display in the right section of the window depends on what is selected in the left pane.
Left pane—Analyzer List
Always displays a tree diagram of the Analyzers and the folders they are stored in.
Right Pane
The right pane displays a variety of different information depending upon what is selected from the tree diagram in the left pane.
You can display information for the following:
Right Pane for Analyzers
In the Index Impact Analyzer window, when an Analyzer is selected in the left pane.
Properties Button
The Properties displays the following information:
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General information about the analysis
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Connection information used to retrieve the access plans and the SQL statements used in the analysis
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Connection information used to retrieve the Baseline access plans
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Indexes used for each Scenario
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SQL Information for each SQL statement used in the analysis