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QDS_CLEANUP_STALE_QUERIES_TASK_MAIN_LOOP_SLEEP

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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):

  1. Waiting between old query data cleanup operations

Abbreviated call stacks (list number matches known occurrences list):

  1. SOS_Task::PostWait+9e
    SOS_Semaphore::Wait+1a2
    CQDSManager::CleanupStaleData+4b3
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+a8