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Description:
This wait type is when a thread is performing operations while a query is pulling data from an XEvent session live data viewer (possibly in SSMS). Note that this is a preemptive wait, so the thread continues executing on the processor until the operation is complete.
(Books Online description: N/A)
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Added in SQL Server version:
2012
Removed in SQL Server version:
N/A
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 734 in 2012 and 752 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.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for a session events to collect data while watching in a live data viewer
Abbreviated call stacks (list number matches known occurrences list):
- SOS_Task::PostWait+9e
SOS_Semaphore::Wait+1a2
XE_LiveTargetTVF::InternalGetRow+ef
CQScanTVFStreamNew::GetRow+d5
CQueryScan::GetRow+81
CXStmtQuery::ErsqExecuteQuery+54a
CXStmtSelect::XretExecute+2e7
CMsqlExecContext::ExecuteStmts<1,1>+427
CMsqlExecContext::FExecute+a43
CSQLSource::Execute+86c
ExecuteSql+863
CSpecProc::ExecuteSpecial+2a2
CSpecProc::Execute+2c5
process_request+a57
process_commands+4a3
SOS_Task::Param::Execute+21e
SOS_Scheduler::RunTask+ab