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.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.