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This wait type is when a thread is waiting for access to the data structure that controls parallel redo on an availability group replica.
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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 1130 in 2016 RTM. After 2016 RTM, you must check the DMV to get the latest value as some map_key values have changed in later builds.
On some servers running builds before SQL Server 2016 SP1 CU2, this wait type is the symptom of a crippling bottleneck during redo of transaction log records on an AG replica. If you are experiencing this, you can turn on trace flag 3459 using DBCC TRACEON (3459, -1), or adding it as a startup trace flag using the Configuration Manager, to disable parallel redo on that instance.
Known occurrences in SQL Server (list number matches call stack list):
Abbreviated call stacks (list number matches known occurrences list):