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Description:
This latch class is when a thread is waiting for access to a cache of results from query permissions checks. This cache prevents having to actually perform the permissions check each time a query is executed.
(Books Online description: N/A)
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Added in SQL Server version:
pre-2005/2005
Removed in SQL Server version:
N/A
Extended Events latch_class value:
The map_key value in sys.dm_xe_map_values is 138 in 2008 and 2008 R2, and 135 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):
- Checking the permissions for a query before it is executed
And other similar call stacks.
Abbreviated call stacks (list number matches known occurrences list):
- XeSqlPkg::latch_suspend_end::Publish+e2
LatchBase::Suspend+1002
LatchBase::AcquireInternal+1ff
ISECManager::FCheckQueryPermissions+23a
CEnvCollection::XretSchemaChanged+c5
CXStmtCondWithQuery::XretExecute+147
CMsqlExecContext::ExecuteStmts<1,1>+375
CMsqlExecContext::FExecute+97e
CSQLSource::Execute+7b5