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.

Nested Class Summary

Nested Classes

Modifier and Type	Interface and Description
static interface	BuiltInMetadata.NonCumulativeCost.Handler Handler API.

Field Summary

Fields

Modifier and Type	Field and Description
static MetadataDef<BuiltInMetadata.NonCumulativeCost>	DEF

Method Summary

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

Field Detail

DEF

static final MetadataDef<BuiltInMetadata.NonCumulativeCost> DEF

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, org.apache.calcite.rel.metadata.RelMetadataQuery), but metadata providers can override this with their own cost models.

Returns:

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