Interval processing and reorganization recommendation

Db2 Query Monitor interval performance history files might be deleted based on the values specified for the RETAIN parameter in CQMPARMS. The RETAIN parameter specifies the number of prior intervals that are to be retained on DASD after interval processing is complete.

For information about the RETAIN parameter, see Query Monitor Subsystem parameters.

For reorganization recommendation, the CAE Server keeps the performance history files for any intervals that are needed for reorganization analysis. When the intervals are no longer needed for reorganization analysis, the performance history files are released. If the interval time period is different from the performance window time period, then the CAE Server initiates interval processing at the start or end time of the performance window.

If the start or end of a performance window is aligned with the start or end of Db2 Query Monitor intervals, then the intervals are not split. For example, if Db2 Query Monitor is configured to snap intervals each hour, and the performance window starts and ends at the beginning of the hour (1:00, 2:00, 3:00, 4:00, ...), Db2 Query Monitor intervals are not split. If the performance window starts in the middle of a Db2 Query Monitor interval, for example, 12:30 till 13:30, then the intervals are split to accommodate this. In this situation, the Db2 Query Monitor intervals are split into the following intervals:

• 11:00 - 12:00
• 12:00 - 12:30
• 12:30 - 13:00 (part of performance window)
• 13:00 - 13:30 (part of performance window)
• 13:30 - 14:00
• 14:00 - 15:00