Determining unnecessary MQTs

 

You can easily determine which MQTs are being used for query optimization. However, you can now easily find all MQTs and retrieve statistics on MQT usage as a result of iSeries™ Navigator and i5/OS™ functionality.

To assist you in tuning your performance, this function now produces statistics on MQT usage in a query. To access this through the iSeries Navigator, navigate to: Database > Schemas > Tables. Right-click your table and select Show Materialized Query Tables.

You can also view the statistics through an application programming interface (API).

In addition to all existing attributes of an MQT, two new fields have been added to the iSeries Navigator.

These new fields are:

Last Query Use

States the timestamp when the MQT was last used by the optimizer to replace user specified tables in a query.

Query Use Count

Lists the number of instances the MQT was used by the optimizer to replace user specified tables in a query.

The fields start and stop counting based on your situation, or the actions you are currently performing on your system. A save and restore procedure does not reset the statistics counter if the MQT is restored over an existing MQT. If an MQT is restored that does not exist on the server, the statistics are reset.

 

Parent topic:

Materialized query table optimization

 

Related information

Retrieve member description (QUSRMBRD) command