The database system determines a series of statistical information when it is running, such as the number of table entries, the sizes of the tables and indices and the value distribution of indices and columns. These statistics are saved in the database catalog.
The SQL Optimizer requires these statistics to determine the best strategy for processing complex SQL statements. You therefore have to update these statistics at regular intervals.
We recommend that you update the statistics once a week. Always update the statistics whenever the size relationships or values in the database instance change considerably.
To update the statistics, use the Database Manager or XPU database tools.
· Database Manager GUI, Update Statistics Information
· Database manager CLI, Updating the Optimizer Statistics
· XPU, Updating the Optimizer Statistics