QDS_ASYNC_QUEUE

(Republishing, or using this info in a commercial product/website, is prohibited without permission. All other uses are permitted. If in doubt, please ask.)

(Back to main page…)

Description:

This wait type is when a thread is waiting for access to the queue of query store information that is asynchronously persisted to disk.

(Books Online description: N/A)

Questions/comments on this wait type? Click here to send Paul an email, especially if you have any information to add to this topic.

Added in SQL Server version:

2016

Removed in SQL Server version:

N/A

Extended Events wait_type value:

The map_key value in sys.dm_xe_map_values is 1102 in 2016 RTM. After 2016 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 for access to the queue (in this case, the background task that persists query store information to disk)

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

  1. SOS_Task::PostWait+6f
    SOS_Semaphore::Wait+16c
    CQDSAsyncPersistManager::FnAsyncPersistTask+12a
    SOS_Task::Param::Execute+231
    SOS_Scheduler::RunTask+aa