org.apache.calcite.rel.metadata

Interface BuiltInMetadata.NonCumulativeCost

All Superinterfaces:

Metadata

Enclosing class:

BuiltInMetadata

public static interface BuiltInMetadata.NonCumulativeCost
extends Metadata

Metadata about the cost of evaluating a relational expression, not including its inputs.

Method Summary

Methods

Modifier and Type	Method and Description
RelOptCost	getNonCumulativeCost() Estimates the cost of executing a relational expression, not counting the cost of its inputs.

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

rel

Method Detail

getNonCumulativeCost

RelOptCost getNonCumulativeCost()

Estimates the cost of executing a relational expression, not counting the cost of its inputs. (However, the non-cumulative cost is still usually dependent on the row counts of the inputs.) The default implementation for this query asks the rel itself via RelNode.computeSelfCost(org.apache.calcite.plan.RelOptPlanner), but metadata providers can override this with their own cost models.

Returns:

estimated cost, or null if no reliable estimate can be determined