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METADATA_CLONE_ACCESS_TICKET

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Description:

Unclear, but from the call stack, I think this latch class is when a thread is waiting for access to a copy of an object’s metadata.

(Books Online description: none)

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Added in SQL Server version:

2008

Removed in SQL Server version:

N/A

Extended Events latch_class value:

The map_key value in sys.dm_xe_map_values is 145 in 2008 and 2008 R2, and 142 in 2012 and 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 latch be a noticeable contention point.

See the LATCH_EX wait type for more information about latches in general and how to troubleshoot them.

Known occurrences in SQL Server (list number matches call stack list):

  1. Generating or using a specified identity value

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

  1. XeSqlPkg::latch_suspend_end::Publish+138
    LatchBase::Suspend+16b8
    LatchBase::AcquireInternal+415
    CMEDSeqGen::AddGeneratedValue+1e0
    CMEDProxyIdentity::AddGeneratedValue+2f
    SetidentI2I4+13a
    sqlTsEs.dll!CEsExec::GeneralEval+1a9
    CQScanUpdateNew::GetRow+43d
    CQScanXProducerNew::GetRowHelper+53
    CQScanXProducerNew::GetRow+15
    FnProducerOpen+57
    FnProducerThread+8c3
    SubprocEntrypoint+a7f
    SOS_Task::Param::Execute+21e
    SOS_Scheduler::RunTask+a8