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(Books Online description: “Occurs during synchronization of query optimizer diagnostic output production. This wait type only occurs if diagnostic settings have been enabled under direction of Microsoft Product Support.”)
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Added in SQL Server version:
Removed in SQL Server version:
Extended Events wait_type value:
The map_key value in sys.dm_xe_map_values is 281 in 2008 and 2008 R2, 288 in 2012, and 295 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.
Known occurrences in SQL Server (list number matches call stack list):
Abbreviated call stacks (list number matches known occurrences list):