IBM Books

Post Threshold Sorts


Snapshot Information Level
Database Manager

API Structure(s)
sqlm_db2

Monitor Group
Sort

Resettable

Yes

 

API Element Name
Element Type

post_threshold_sorts
counter

 

Description:  The number of sorts that have requested heaps after the sort heap threshold has been reached.

Usage:  Under normal conditions, the database manager will allocate sort heap using the value specified by the sortheap configuration parameter. If the amount of memory allocated to sort heaps exceeds the sort heap threshold (sheapthres configuration parameter), the database manager will allocate sort heap using a value less than that specified by the sortheap configuration parameter.

Each active sort on the system allocates memory, which may result in sorting taking up too much of the system memory available. Sorts that start after the sort heap threshold has been reached may not receive an optimum amount of memory to execute, but, as a result, the entire system may benefit. By modifying the sort heap threshold and sort heap size configuration parameters, the performance of sort operations and/or the overall system can be improved. If this element's value is high, you can:

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