Manage Optimizer Statistics on Autonomous Database

Describes Autonomous Database commands to run when you need to gather optimizer statistics or enable optimizer hints.

Managing Optimizer Statistics

Autonomous Database gathers optimizer statistics automatically so that you do not need to perform this task manually and this helps to ensure your statistics are current. Automatic statistics gathering is enabled in Autonomous Database and runs in a standard maintenance window.

Note:

The automatic statistics gathering maintenance window is different than the maintenance window on the Oracle Cloud Infrastructure console. The Oracle Cloud Infrastructure maintenance window shows system patching information.

For more information on automatic statistics gathering maintenance window times and automatic optimizer statistics collection, see Database Administrator’s Guide.

For more information on optimizer statistics see SQL Tuning Guide.

Managing Optimizer Hints

Autonomous Database honors optimizer hints and PARALLEL hints in SQL statements by default. You can disable optimizer hints by setting the parameter OPTIMIZER_IGNORE_HINTS to TRUE at the session or system level using ALTER SESSION or ALTER SYSTEM. For example, the following command disables hints in your session:

ALTER SESSION
   SET OPTIMIZER_IGNORE_HINTS=TRUE;

You can also disable PARALLEL hints in your SQL statements by setting OPTIMIZER_IGNORE_PARALLEL_HINTS to TRUE at the session or system level using ALTER SESSION or ALTER SYSTEM.

ALTER SESSION 
   SET OPTIMIZER_IGNORE_PARALLEL_HINTS=TRUE;