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Description:
This wait type is when a thread is waiting for a read from a trace file to complete.
(Books Online description: N/A)
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Added in SQL Server version:
2008 R2
Removed in SQL Server version:
N/A
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 601 in 2008 R2, 683 in 2012, and 701 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, but I suppose these waits may become longer if there is I/O subsystem contention.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for a read from a trace file to complete
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):
- SOS_Task::PostWait+90
EventInternal<SuspendQueueSLock>::Wait+1f9
CTraceReadBuf::WaitForIoCompletion+bc
CTraceFileReader::GetNextBlock+10e
CRowsetTraceTable::OpenNextFile+128
CRowsetTraceTable::GetRowImpl+2b0
CRowsetTraceTable::GetRow+23
CQScanTVFStreamNew::GetRow+d5
CQScanFilterNew::GetRowHelper+20
CQueryScan::GetRow+81
CXStmtQuery::ErsqExecuteQuery+54a
CXStmtSelect::XretExecute+2f7
CMsqlExecContext::ExecuteStmts<1,1>+400
CMsqlExecContext::FExecute+a33
CSQLSource::Execute+866
process_request+73c
process_commands+51c
SOS_Task::Param::Execute+21e
SOS_Scheduler::RunTask+a8