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

Applies to: SQL Server 2014 DeveloperSQL Server 2014 EnterpriseSQL Server 2014 Enterprise Core

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.

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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