org.apache.calcite.rel.metadata

Interface BuiltInMetadata.Selectivity

All Superinterfaces:

Metadata

Enclosing class:

BuiltInMetadata

public static interface BuiltInMetadata.Selectivity
extends Metadata

Metadata about the selectivity of a predicate.

Method Summary

Methods

Modifier and Type	Method and Description
Double	getSelectivity(RexNode predicate) Estimates the percentage of an expression's output rows which satisfy a given predicate.

Methods inherited from interface org.apache.calcite.rel.metadata.Metadata

rel

Method Detail

getSelectivity

Double getSelectivity(RexNode predicate)

Estimates the percentage of an expression's output rows which satisfy a given predicate. Returns null to indicate that no reliable estimate can be produced.

Parameters:

predicate - predicate whose selectivity is to be estimated against rel's output

Returns:

estimated selectivity (between 0.0 and 1.0), or null if no reliable estimate can be determined