Deletion of Damaging Statistics

Use

This section describes how BRCONNECT deletes damaging statistics for the cost-based optimizer of the Oracle database.

Pool and cluster tables (for Oracle 9i only) and tables that have the ACTIVE flag set to N or R in the DBSTATC control table should not normally have statistics, since such statistics can negatively affect database performance.

Activities

In the standard update statistics run, using brconnect -f stats -t all, BRCONNECT checks whether such damaging statistics exist and deletes them if so.

You can delete such damaging statistics immediately:

brconnect -u / -c -f stats –t harmful -d

To delete statistics for other tables as well (only for test purposes), you can use the option -f allsel:

brconnect -u / -c -f stats -t sdbah,sdbad -d -f allsel

Starting with Oracle 10g, all tables generally have optimizer statistics.