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BiasQueriesAsOutlier

Set query optimization to biased toward outliers.

Synopsis

[SQL]    BiasQueriesAsOutlier=n

n is either 1 or 0. The default value is 0.

Description

When BiasQueriesAsOutlier is enabled (n = 1), InterSystems SQL optimizes for queries that primarily return outlier values. For further details on outlier selectivity, refer to Tune Table in the “Optimizing Tables” chapter in InterSystems SQL Optimization Guide.

BiasQueriesAsOutlier cannot be set to 1 if the parameter RTPC is also set to 1. When RTPC is set, InterSystems SQL determines whether to use outlier optimization on a per-query basis.

Changing This Parameter

On the SQL page of the Management Portal (System Administration > Configuration > SQL and Object Settings > SQL), for the Optimize queries based on parameter values setting, choose Assume query parameter values often match field outliers.

You can also change BiasQueriesAsOutlier with the Config.SQL class (as described in the class reference) or by editing the CPF in a text editor (as described in the Editing the Active CPF section of the “Introduction to the Configuration Parameter File” chapter in this book).