15.5.6 Checking execution status

You can check whether the free space reusage facility is effective from the items in the table below. This checking can be made with the database condition analysis utility, the statistics analysis utility, or the UAP statistical report facility. If this fails, the KFPH22031-W message is output to the message log for each table (for the partitioning RDAREA in the case of a partitioned table). The items and their explanation follow:

ItemExplanationMeasure
Number of page search mode switchoversThis is the number of times the search mode switches from the new page allocate mode to the free page reusage mode, or vice versa. Frequent switchover during allocation of reused and unused segments means that there is more added space than available space due to deletions and that the segment size (number of pages) is too small.Consider changing the segment size or the timing of deletion execution.
Number of failed page searches by the free space reusage facilityThe number of used segments reaches the number of specified segments, but even upon switchover to the free page reuse mode, there are no free pages available. In such a case, the number of search failures increases. Because a search is conducted even though there is no free space, pointless search processing is performed.
If the number of failed page searches by the free space reusage facility and the number of page search mode switchovers both increase, then free page reusage is being executed when there is absolutely no free space.
Re-evaluate the specified number of segments and the segment size, or consider stopping the free space reusage facility.
Number of used segmentsIf there is no free space in the segments used by a table, unused segments will be allocated, causing the number of the table's used segments to increase. If the increase exactly matches the number of failed free space reusage page searches, search processing to find free space will continue even though there is none.[Figure]
Legend:
[Figure]: Not applicable.