DB2 Version 9.7 for Linux, UNIX, and Windows

post_shrthreshold_hash_joins - Post threshold hash joins monitor element

The total number of hash joins that were throttled back by the sort memory throttling algorithm. A throttled hash join is a hash join that was granted less memory than requested by the sort memory manager.

Table 1. Snapshot Monitoring Information
Snapshot Level	Logical Data Grouping	Monitor Switch
Database	dbase	-

For snapshot monitoring, this counter can be reset.

Table 2. Event Monitoring Information
Event Type	Logical Data Grouping	Monitor Switch
Database	event_db	-

A hash join is throttled back when the memory allocation from the shared sort heap is close to the limit set by database configuration parameter sheapthres_shr. This throttling will significantly reduce the number of overflows over sheapthres_shr limit in a system that is not properly configured. The data reported in this element only reflects hash joins using memory allocated from the shared sort heap.