Package org.apache.calcite.rel.metadata
Interface BuiltInMetadata.NonCumulativeCost
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- 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.
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Nested Class Summary
Nested Classes Modifier and Type Interface Description static interface
BuiltInMetadata.NonCumulativeCost.Handler
Handler API.
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Field Summary
Fields Modifier and Type Field Description static MetadataDef<BuiltInMetadata.NonCumulativeCost>
DEF
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Method Summary
All Methods Instance Methods Abstract Methods Modifier and Type Method Description RelOptCost
getNonCumulativeCost()
Estimates the cost of executing a relational expression, not counting the cost of its inputs.
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Field Detail
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DEF
static final MetadataDef<BuiltInMetadata.NonCumulativeCost> DEF
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Method Detail
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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 viaRelNode.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
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