About Automated Maintenance Tasks

Automated maintenance tasks are tasks that are started automatically at regular intervals to perform maintenance operations on the database. An example is a task that gathers statistics on schema objects for the query optimizer. Automated maintenance tasks run in maintenance windows, which are predefined time intervals that are intended to occur during a period of low system load. You can customize maintenance windows based on the resource usage patterns of your database, or disable certain default windows from running. You can also create your own maintenance windows.

Oracle Database has three predefined automated maintenance tasks:

  • Automatic Optimizer Statistics Collection—Collects optimizer statistics for all schema objects in the database for which there are no statistics or only stale statistics. The statistics gathered by this task are used by the SQL query optimizer to improve the performance of SQL execution.

    See Also:

    Oracle Database Performance Tuning Guide for more information on automatic statistics collection
  • Automatic Segment Advisor—Identifies segments that have space available for reclamation, and makes recommendations on how to defragment those segments.

    You can also run the Segment Advisor manually to obtain more up-to-the-minute recommendations or to obtain recommendations on segments that the Automatic Segment Advisor did not examine for possible space reclamation.

    See Also:

    "Using the Segment Advisor" for more information.
  • Automatic SQL Tuning Advisor—Examines the performance of high-load SQL statements, and makes recommendations on how to tune those statements. You can configure this advisor to automatically implement SQL profile recommendations.

    See Also:

    Oracle Database Performance Tuning Guide for more information on SQL Tuning Advisor

By default, all three automated maintenance tasks are configured to run in all maintenance windows.