On, Off

On

The database server collects statistics during normal query execution and uses the gathered statistics to self-tune the column statistics. When you set this option to Off, the statistics governor does not receive feedback about the health of statistics or fix any statistics for the specified connection. However, it does continue to monitor the usage of statistics and create or drop statistics based on their usage.

When this option is set by a user with DBA authority, its setting affects all connections to the database; otherwise, only the current users connections are affected.

Under normal circumstances, it should not be necessary to turn this option off.

The update_statistics option does not affect changes to statistics as a result of updates to data (LOAD/INSERT/UPDATE/DELETE). To control whether statistics are updated based on these statements, use the collect_statistics_on_dml_updates database option.

The difference between the collect_statistics_on_dml_updates option and the update_statistics option is that the update_statistics option compares the actual number of rows that satisfy a predicate with the number of rows that are estimated to satisfy the predicate, and then updates the estimates. The collect_statistics_on_dml_updates option modifies the column statistics based on the values of the specific rows that are inserted, updated, or deleted.

• collect_statistics_on_dml_updates option
• How the statistics governor maintains statistics
• Updating column statistics to improve optimizer performance
• update_statistics connection property