This section describes how to configure persistent and
non-persistent optimizer statistics for
tables. Persistent optimizer statistics were introduced in MySQL
5.6.2 and were made the default in MySQL 5.6.6
Persistent optimizer statistics are persisted across server restarts, allowing for greater plan stability and more consistent query performance. Persistent optimizer statistics also provide control and flexibility with these additional benefits:
You can use the
configuration option to control whether statistics are updated
automatically after substantial changes to a table.
You can query optimizer statistics data in the
You can view the
last_update column of the
mysql.innodb_index_stats tables to see when
statistics were last updated.
You can manually modify the
mysql.innodb_index_stats tables to force a
specific query optimization plan or to test alternative plans
without modifying the database.
Non-persistent optimizer statistics are cleared on each server restart and after some other operations, and recomputed on the next table access. As a result, different estimates could be produced when recomputing statistics, leading to different choices in execution plans and variations in query performance.
This section also provides information about estimating
ANALYZE TABLE complexity, which may
be useful when attempting to achieve a balance between accurate