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This wait type appears to be when a thread for certain batch-mode query operations is waiting for other such threads to finish initializing.
(Books Online description: N/A)
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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 696 in 2012 and 714 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.
I have not seen this thread be a noticeable contention point.
Known occurrences in SQL Server (list number matches call stack list):
- Waiting for other parallel threads to finish initializing while running a hash join involving a columnstore index
And many other similar callstacks.
Abbreviated call stacks (list number matches known occurrences list):