KB4460116 - FIX: Overestimations when using default Cardinality Estimator to query table with many null values

Symptoms

Assume that you have Microsoft SQL Server 2014, 2016 and 2017 installed. You have a table column that contains many null values, and you execute a query on that table by using the default Cardinality Estimator (CE). In this scenario, you may experience an overestimation in a filter that compares the table column to a value that's unknown at compile time.

Resolution

This issue is fixed in the following updates for SQL Server:

          Cumulative Update 13 for SQL Server 2017

          Cumulative Udpate 4 for SQL Server 2016 SP2

          Cumulative Update 12 for SQL Server 2016 SP1

          Cumulative Update 1 for SQL Server 2014 SP3

Cumulative Update 14 for SQL Server 2014 Service Pack 2

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: 

Latest cumulative update for SQL Server 2017

Latest cumulative update for SQL Server 2016

The latest cumulative updates for SQL Server 2014

Status

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

References

Cardinality Estimation (SQL Server)

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