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Statistics Collection Enhancements in Oracle Database 12c Release 1 (12.1)

Oracle database 12c includes a number of new features related to statistics collection. Many of these features have been covered separately, so this article serves to bring all the features together.

Related articles.

Enhancements to Incremental Statistics

Oracle 11g enhanced the collection of incremental statistics, such that partition level statistics could be used to accurately calculate global statistics, described here. In 11g, a partition exchange marks the statistics as stale on the new segment, even if they were up to date before the operation. This means the statistics on the partition must be gathered again before they are considered valid and used to update the global statistics.

Oracle 12c now supports the use of statistics for a segment used in a partition exchange. Provided the original segment has valid statistics, they will be used to amend the global statistics, removing the need to regather the statistics on the new partition once the exchange is complete.

Enhancements to System Statistics

The DBMS_STATS.GATHER_SYSTEM_STATS procedure includes a new GATHERING_MODE of EXADATA. This includes additional tests specific for Exadata systems. According to the documentation, "the multi-block read count and IO throughput statistics are set along with the CPU speed." This was present in 11gR2, but it was not documented, so it is now documented as a new feature in the database documentation.

For more information see:

Hope this helps. Regards Tim...

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