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RTPC

Enable Runtime Plan Choice (RTPC) query optimization.

Synopsis

[SQL]    RTPC=n

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

Description

When RTPC is enabled (n = 1), InterSystems SQL queries can perform optimization based on outlier information. For further details on outlier selectivity, refer to Tune Table in the “Optimizing Tables” chapter in InterSystems SQL Optimization Guide.

RTPC cannot be set to 1 if the BiasQueriesAsOutlier parameter is also set to 1. When BiasQueriesAsOutlier is set, InterSystems SQL is optimized for queries that often refer to the outlier.

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 Optimize for actual query parameter values at runtime.

To set the desired value for RTPC from the Terminal, use the SetRTPC() method of the %SYSTEM.SQL class. See the class reference for details.

You can also change RTPC 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).