Registration

Dear SAP Community Member,
In order to fully benefit from what the SAP Community has to offer, please register at:
http://scn.sap.com
Thank you,
The SAP Community team.
Skip to end of metadata
Go to start of metadata

SAP® MaxDB - SQL Optimizer

 

This section gives detailed information about the SAP MaxDB SQL Optimizer.

Moderators: Christiane Hienger

WIKI Space Editor: Thiago Lüttig.

SQL statements describe the content criteria, which the data that has to be accessed has to meet. But it does not describe how this data is to be accessed.

Each relational operation can, in principle, be converted into different access operations. But these can lead to different runtimes, for example, depending on the amount of data. Hence the scope of functions and the performance of the optimizer are of utmost importance.

SQL Optimizer

Terminology

This section introduces you to the performance analysis terms of the SQL optimizer.

Introduction to SQL Optimizer

This page deals with information about the purpose and aim of the SQL optimizer and gives an introduction to the topics Qualification, Search Area, Join.... This is where subjects such as cost or rule-based SQL optimizer and the special evaluation feature of SAP MaxDB are explained.

SAP MaxDB Optimizer Strategies

This section explains SAP MaxDB optimization strategies.

Execution Plans (EXPLAIN)

The execution plan shows which strategy the Optimizer has chosen for accessing the data requested by means of the SQL statement. Hence, it is well-suited to analyzing long-running SQL statements.

SQL Optimizer Hints

The SQL optimizer usually determines the access path on the basis of the costs (cost-based SQL optimizer). To deactivate this mechanism, you can explicitly specify hints for an SQL statement, which force a certain access path. In this section you get detailed information about SAP MaxDB hints.