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SQL Optimizer for SAP ASE 3.9.1 - User Guide

Introduction Tutorials Preferences Editor Functions SQL Information and Functions Performance Monitor SQL Inspector SQL Collector for Monitor Server SQL Scanner Index Advisor SQL Optimizer
SQL Optimizer Overview Optimization Engine Common Coding Errors in SQL Statements What Function Should l Use to Retrieve the Run Time? Unsatisfactory Performance Results SQL Optimizer Functions SQL Editor Optimized SQL Activity Log
SQL Worksheet SQL Formatter Database Explorer Code Finder Object Extractor SQL Repository Index Impact Analyzer Index Usage Analyzer Configuration Analyzer Migration Analyzer Abstract Plan Manager User-Defined Temp Tables SQL History Legal Information

Copy SQL with Temporary Tables to SQL Optimizer

When you copy a SQL statement from the SQL Scanner to the SQL Optimizer module, the Send to SQL Optimizerfunction automates this process for you. It copies the SQL statement, opens the SQL Optimizer window and inserts the SQL statement in the SQL Editor pane. When the SQL statement you are copying also includes a temporary table, the Send to SQL Optimizer function also copies the SQL statements for creating and populating the temporary table to the User-Defined Temp Table module.

Two items need to be considered when the SQL statements are automatically copied in the User-Defined Temp Table module. Is there SQL text already in the module? And does the temporary table already exist with the same or different data?

If SQL text is already entered into the User-Defined Temp Table module, you are prompted to save the current SQL to an ASCII file before it is overlaid with the new text. Saving the text enables you to use it again.

If a table with the same name already exists and you would like to recreate it with either a new definition or different data, then you must drop the table before executing the new SQL text. You can drop temporary table from the Temp Table List tab in the User-Defined Temp Table module.

 

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Create Alternative SQL Which Uses Temporary Tables

One of the techniques for improving the performance of a SQL statement is to create a temporary table. When the SQL Optimizer rewrites the original SQL statement, some of the alternatives may involve this technique.

Here is an illustration of the original SQL and one of the SQL alternatives.

Original SQL

SELECT *

FROM A  

WHERE A.KEY IN (SELECT B.KEY  

FROM B)                   

SQL1 Alternative

SELECT DISTINCT COL1 = B.KEY INTO #TEMP1 FROM B

SELECT *

FROM A, #TEMP1  

WHERE A.KEY = #TEMP1.COL1 

DROP TABLE #TEMP1

Note: Under the Optimization tab in the Preferences, the section on Temp Table Generation enables you to specify whether to allow the generation of temporary tables during the optimization process.

 

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Preference Settings for Handling Temporary Tables

Under the Preferences window, the SQL Scanner and Optimization tabs contain several settings that control the use of temp tables in the SQL Scanner and SQL Optimizer modules.

SQL Scanner Tab

Optimization Tab

 

Related Topics

SQL History

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