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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_CONSUMER, 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 open, close, and synchronize Exchange Iterator ports between producer and consumer threads. For example, if a query plan has a long sort operation, CXSYNC_PORT waits may be higher because the sort must complete before the Exchange Iterator port can be synchronized.”)
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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):