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.
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.