When you run a merge statement in Microsoft SQL Server, a deadlock condition may occur between the merge operation and a background thread on the Clustered Columnstore Index (CCI) table. However, SQL Server does not detect the deadlock.
No error report is logged if trace flag 1222 is enabled.
No event is logged if you use the XEvent log to capture deadlocks and then try to trigger the event.
This issue is fixed in Cumulative Update 11 for SQL Server 2014 Service Pack 2.
Each new cumulative update for SQL Server contains all the hotfixes and security fixes that were in the previous build. Check out the latest cumulative updates for SQL Server 2014.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
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