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The simplest explanation of this wait type is that there are parallel plans running. This wait type was added in Azure SQL Database and Azure SQL Managed Instance and is now in SQL Server 2022. This, along with CXSYNC_PORT, were split out from CXPACKET in a bid to make investigating parallel plan performance issues easier.
I do not have any experience with this wait yet.
Do not just reduce the server MAXDOP to try to reduce or remove these! See CXPACKET for more information.
(Books Online description: “Occurs with parallel query plans when waiting to reach an Exchange Iterator synchronization point among all consumer threads.”)
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Added in SQL Server version:
Azure SQL Database, Azure SQL Managed Instance, SQL Server 2022.
Removed in SQL Server version:
Extended Events wait_type value:
Known occurrences in SQL Server (list number matches call stack list):
Abbreviated call stacks (list number matches known occurrences list):