Assume that you have Clustered Columnstore Index (CCI) on a table in SQL Server 2017 or 2019. When you run versioned scans (such as Snapshot Isolation (SI) or Read Committed Snapshot Isolation (RCSI)), and if a "tuple mover" merge or "alter index reorganize" process is also running on the same table, you receive wrong results.


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


This problem is fixed in the following cumulative updates for SQL Server:

Each new cumulative update 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:


Learn about the terminology that Microsoft uses to describe software updates.

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