Consider the following scenario:
- You execute a query in Microsoft SQL Server 2016 and 2017.
- The resulting query plan contains a batch mode branch and a row mode branch involved in a JOIN.
- In the row mode branch there are parallel and serial operators.
In this scenario, a deadlock condition might occur.
Note: This issue does not occur if you set the max degree of parallelism (MAXDOP) to 1 for the query.
This issue is fixed in the following cumulative updates for SQL Server:
Note The query optimizer hotfix trace flag (TF) 4199 must be enabled for this issue to be resolved.
For more information about query optimizer hotfixes and trace flags, see:
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.