SQL Optimizer 

Purpose

The SQL Optimizer analyzes SQL queries on the database from users or applications. When the SQL query is specified with particular search conditions, the SQL Optimizer can optimize the access to the data, meaning that it uses a cost determination and the existing statistics of the SQL Optimizer to select the best search strategy for accessing the data records.

Integration

The SQL Optimizer is part of the database kernel.

See also:

Concepts of the Database System, Performance

In SAP systems, you can use the DBA Planning Calendar to display information about the SQL Optimizer and schedule actions and statistic updates.

See also:

Database Administration in CCMS: MaxDB, SQL Optimizer in CCMS

Features

The SQL Optimizer is called by the database system implicitly (see How the SQL Optimizer Operates).

You can use the EXPLAIN SQL statement to find out which search strategy was selected by the SQL Optimizer for an SQL statement (see Troubleshooting).

Examples

The examples used to explain the SQL Optimizer are based on the demo database DEMODB and its complete demo data in the schema HOTEL.

See also:

Concepts for the Database System, Demo Database, Objects in the HOTEL Schema