How Db2 Query Monitor clears or overrides a baseline performance window

At the beginning of a performance window, Db2 Query Monitor checks the system tables to determine when the latest reorganization was completed for the objects of interest.

• If the reorganization was completed after the baseline performance window start time, Db2 Query Monitor deletes the baseline performance window and creates a new one with data from current performance window. This overriding of the existing baseline performance window with a new one is done to ensure the use of the latest statistics.
• If Db2 Query Monitor does not find information about the objects in the system tables, it deletes the baseline for the objects.

The CQM_REORG_METRICS parameter is applied when Db2 Query Monitor receives information about the objects and the time period to be monitored (the performance window) from Db2 Automation Tool. The metrics that Db2 Query Monitor collects are stored in the reorganization history (knowledge/site/qm/reorg/history). Changes made to CQM_REORG_METRICS are not applied to previously collected metrics.

The metrics are later used to evaluate the baseline and performance windows for a reorganization profile, with the values that were in place when the profile was received from Db2 Automation Tool.

When a job profile is built, Db2 Automation Tool sends information about the objects and the time period to be monitored (the performance window) to Db2 Query Monitor.