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(Books Online description: “Used to synchronize the access to a cache of extents that contains pages that are not allocated. Contention on latches of this class can occur when multiple connections try to allocate data pages in the same allocation unit at the same time. This contention can be reduced by partitioning the object of which this allocation unit is a part.”)

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Added in SQL Server version:


Removed in SQL Server version:


Extended Events latch_class value:

Maps to the AEC map_value in sys.dm_xe_map_values.

The map_key value in sys.dm_xe_map_values is 5 in 2008 and 2008 R2.

Other information:


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

  1. TBD

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

  1. TBD