MAXSEGRATIO= Parameter File Option

Controls segment candidate pre-evaluation for WHERE clause predicates with a hybrid index.

Valid in: spdsserv.parm parameter file
Default: 75
Syntax
Required Argument
Details

Syntax

MAXSEGRATIO=n;

Required Argument

n

specifies a number indicating the percentage of possible segments from the total number of segments that can be candidate segments before pre-evaluation is not performed. If you omit this value, the default value is 75%.

Details

The WHERE clause planner pre-evaluates the segment candidates for the predicate. Only the segment candidates are searched to resolve the WHERE clause. Some queries can benefit from not performing pre-evaluation, based on the ratio of the number of segments that contain candidates to the total number of segments in the file. If the percentage of possible segments exceeds MAXSEGRATIO=, pre-evaluation is not performed, and all of the segments are searched to resolve the WHERE clause.
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Last updated: February 3, 2017