How intervals are calculated
The start time of the first interval that is processed by REDUCE is influenced by BOUNDARY, INTERVAL, and FROM.
OMEGAMON for Db2 Performance Expert attempts to reduce all data that falls between the FROM and TO times. The first interval starts at a time aligned with BOUNDARY, at or before the FROM time. If an interval cannot be aligned with the FROM time, the first properly aligned interval starting before the FROM time is used. An interval that starts before the FROM time only contains data between the FROM time and the start of the next interval. Input data before the FROM time is not processed.
Although there is no restriction on the INTERVAL and BOUNDARY combination, your specification should comply with the following rules:
- For intervals of less than 60 (excluding 0), there should be a
whole number of intervals in an hour. Choose one of the following
values:
- 1, 2, 3, 4, 5, 6, 10, 12, 15, 20, or 30
- For intervals of 60 or greater, there should be a whole number
of intervals in a day. Choose one of the following values:
- For intervals of one day (1440) or greater, INTERVAL should be a multiple of 1440
- Select your interval and boundary so that the first interval starts at the FROM time
If you do not require interval processing, do not change the default INTERVAL (0) for performance reasons.
Always use the largest interval that meets your reporting requirements. For example, if daily reports provide sufficient granularity, use INTERVAL (1440).