Automatic Optimizer Statistics Collection on Partitioned Table
Last updated on OCTOBER 30, 2017
Applies to:Oracle Database - Enterprise Edition - Version 184.108.40.206 to 220.127.116.11 [Release 11.2]
Information in this document applies to any platform.
This article explains what type of statistics are collected on partitioned tables and when by Automatic Optimizer Statistics Collection job, that by default is running in the maintenance window.
As it is documented in the Oracle® Database Performance Tuning Guide 11g Release:
Automatic optimizer statistics collection calls the DBMS_STATS.GATHER_DATABASE_STATS_JOB_PROC procedure. This internal procedure operates similarly to the DBMS_STATS.GATHER_DATABASE_STATS procedure using the GATHER AUTO option. The main difference is that GATHER_DATABASE_STATS_JOB_PROC prioritizes database objects that require statistics, so that objects that most need updated statistics are processed first, before the maintenance window closes.
To demonstrate the behaviour we use the DBMS_STATS.GATHER_DATABASE_STATS procedure using the GATHER AUTO option in the example below.
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