December 2002
Intermediate to advanced
928 pages
85h 29m
English
The cost-based optimizer can select different execution plans based on different statistics. If you feel that the cost-based optimizer is working appropriately and you don’t want new statistics to change execution plans, you can store the statistics for the database with the DBMS_STATS.EXPORT_SCHEMA_STATS procedure to save them before you update the statistics.
If the new set of statistics does not deliver the desired performance or better, you can use the DBMS_STATS.IMPORT_SCHEMA_STATS procedure to reimport the saved statistics.
You can also store multiple versions of statistics in a statistics table you specify.