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Description:
This wait type is when a thread is waiting for a timer to expire between operations to remove old query information from the query data store.
(Books Online description: N/A)
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Added in SQL Server version:
2014
Removed in SQL Server version:
N/A
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 1022 in 2014 RTM. After 2014 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.
Other information:
I have not seen this wait type be a noticeable contention point.
This wait type is one that I usually filter out as a benign wait when doing wait statistics analysis.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting between old query data cleanup operations
Abbreviated call stacks (list number matches known occurrences list):
- SOS_Task::PostWait+9e
SOS_Semaphore::Wait+1a2
CQDSManager::CleanupStaleData+4b3
SOS_Task::Param::Execute+21e
SOS_Scheduler::RunTask+a8