SQL Optimizer for DB2 LUW 4.3.1 - User Guide

Scanned SQL Viewer Functions

Below is a list of available functions within the Scanned SQL Viewer window.

SQL Optimizer

Quest SQL Optimizer for IBM® DB2® LUWmaximizes 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)

SQL Formatter

Database Explorer

SQL Scanner

SQL Inspector

SQL Repository

Index Impact Analyzer

Index Usage Analyzer

SQL Optimizer Concepts

Quest SQL Optimizer for IBM® DB2® LUWmaximizes 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)

SQL Formatter

Database Explorer

SQL Scanner

SQL Inspector

SQL Repository

Index Impact Analyzer

Index Usage Analyzer

About the SQL Rewrite Function

The SQL Rewrite function analyzes the input SQL statement and uses an Artificial Intelligence Engine to produce a group of semantically equivalent versions of the statement, known as SQL alternatives. You can then test run these alternatives in the SQL Optimizer window to determine the best-performing version of the SQL.

Tip: After you run SQL Rewrite, run the Generate Indexes function to add alternatives that incorporate virtual indexes. You can then test run the SQL alternatives along with index-set alternatives to measure performance. See Generate Index-Set Alternatives for more information.

The SQL Rewrite process includes these phases:

Show Plan

Retrieves the access plan and the DB2 optimized text that the DB2 LUW optimizer has chosen for the specific SQL alternative. SQL Rewrite classifies the SQL statement according to characteristics that cause performance problems. 

Rewrite

Rewrites the original SQL statement to produce a list of semantically equivalent versions, or SQL alternatives.

Run Time/Batch Run

Allows the users to test run the original and the SQL alternatives to select which SQL version gives the best performance. For each alternative, Batch Run provides the run time for retrieving all records and for retrieving only the first record. You can use this information to identify which alternative is most suitable for your application.

Execute

Executes alternatives against the original SQL and displays the returned data for comparison in the SQL Optimizer window.

Related Topics

SQL Optimizer Tutorial

SQL Optimizer Window

SQL Optimizer Functions