Symptoms
Assume that you run Data Analysis Expressions (DAX) queries in Microsoft SQL Server 2017. When you execute a DAX query that contains SWITCH and nested IF statements, if the SWITCH branch is the last in the branch list, the query may take more than an hour to finish. However, if the SWITCH branch is the first in the branch list, the query only takes several seconds to finish.
Resolution
This fix is included in the following update for SQL Server:
About SQL Server builds
Each new build for SQL Server contains all the hotfixes and security fixes that were in the previous build. We recommend that you install the latest build for your version of SQL Server:
Status
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.
References
Learn about the standard terminology that Microsoft uses to describe software updates.
