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SQL Optimizer for SAP ASE 3.8 - 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

Create Alternative SQL Which Uses Temporary Tables

User-Defined Temp Tables > 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.

 

Related Topics

Preference Settings for Handling Temporary Tables

User-Defined Temp Tables > 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

SQL History Overview

SQL History > SQL History Overview

Throughout the program, SQL statements are saved in the SQL History so that you can use them again. They are stored in a file so that they are always available to work with again.

 

Related Topics

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