Auto Update Statistics: Configuration

Use this page to specify the values of the Auto Update Statistics (AUS) configuration parameters.

The AUS maintenance system uses these parameters as criteria for identifying the user tables whose statistics must be recalculated.

AUS_AGE

The maximum number of days between statistics rebuilds. Statistics or distributions are updated for a table after this amount of time regardless of how much data changed. The default is 30.

AUS_AUTO_RULES

An indicator of whether to follow the default minimum guidelines to rebuild the statistics. When the parameter is on, the higher of the default minimum guidelines or the user-created distribution options are used. When the parameter is off, the user-created distribution options are used.

AUS_CHANGE

The percentage of change in a table that triggers rebuilding the statistics. The default is 10 (10 percent). The range of values is 0-100.

AUS_PDQ

The parallel database query (PDQ) priority at which the update statistics statements run. The default value is 10.

AUS_SMALL_TABLES

The number of rows below which statistics are always rebuilt. For example, if the value is 300, then tables with 299 rows or fewer always have their statistics rebuilt. The default value is 100.

Run update statistics with this number of threads

The number of threads to use to run the update statistics tasks. The OpenAdmin Tool (OAT) for Informix® submits this number of AUS tasks to the Task Scheduler. You can improve the efficiency of AUS by running the tasks in parallel. The maximum number of threads is 10.

AUS_DATABASE_HIGH

Sets the priority of updating statistics for the database to high. Higher priority databases have their statistics updated first. The default priority is medium.

AUS_DATABASE_LOW

Sets the priority of updating statistics for the database to low.