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SQL Anywhere 10.0.1 » SQL Anywhere Server - Database Administration » Database Options » Introduction to database options » Alphabetical list of options

updatable_statement_isolation option [database] Next Page

update_statistics option [database]


Controls the gathering of statistics during query execution.

Allowed values

On, Off

Default

On

Remarks

The server collects statistics during normal query execution and uses the gathered statistics to self-tune the column statistics. You can set the update_statistics option Off to disable the gathering of statistics during query execution.

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 accordingly. 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.

See also