org.apache.calcite.rel.rules

Class AggregateValuesRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.plan.RelRule<AggregateValuesRule.Config>

org.apache.calcite.rel.rules.AggregateValuesRule

All Implemented Interfaces:

SubstitutionRule, TransformationRule

@Value.Enclosing
public class AggregateValuesRule
extends RelRule<AggregateValuesRule.Config>
implements SubstitutionRule

Rule that applies Aggregate to a Values (currently just an empty Values).

This is still useful because PruneEmptyRules.AGGREGATE_INSTANCE doesn't handle Aggregate, which is in turn because Aggregate of empty relations need some special handling: a single row will be generated, where each column's value depends on the specific aggregate calls (e.g. COUNT is 0, SUM is NULL).

Sample query where this matters:

SELECT COUNT(*) FROM s.foo WHERE 1 = 0

This rule only applies to "grand totals", that is, GROUP BY (). Any non-empty GROUP BY clause will return one row per group key value, and each group will consist of at least one row.

See Also:

CoreRules.AGGREGATE_VALUES

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static interface	AggregateValuesRule.Config Rule configuration.

Nested classes/interfaces inherited from class org.apache.calcite.plan.RelRule

RelRule.Done, RelRule.MatchHandler<R extends RelOptRule>, RelRule.OperandBuilder, RelRule.OperandDetailBuilder<R extends RelNode>, RelRule.OperandTransform

Nested classes/interfaces inherited from class org.apache.calcite.plan.RelOptRule

RelOptRule.ConverterRelOptRuleOperand

Field Summary

Fields inherited from class org.apache.calcite.plan.RelRule

config

Fields inherited from class org.apache.calcite.plan.RelOptRule

description, operands, relBuilderFactory

Constructor Summary

Constructors

Modifier	Constructor and Description
protected	AggregateValuesRule(AggregateValuesRule.Config config) Creates an AggregateValuesRule.
	AggregateValuesRule(RelBuilderFactory relBuilderFactory) Deprecated.

Method Summary

Modifier and Type	Method and Description
void	onMatch(RelOptRuleCall call) Receives notification about a rule match.

Methods inherited from class org.apache.calcite.plan.RelOptRule

any, convert, convert, convertList, convertOperand, convertOperand, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, operandJ, operandJ, some, toString, unordered

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface org.apache.calcite.rel.rules.SubstitutionRule

autoPruneOld

Constructor Detail

AggregateValuesRule

protected AggregateValuesRule(AggregateValuesRule.Config config)

Creates an AggregateValuesRule.

AggregateValuesRule

@Deprecated
public AggregateValuesRule(RelBuilderFactory relBuilderFactory)

Deprecated.

Method Detail

onMatch

public void onMatch(RelOptRuleCall call)

Description copied from class: RelOptRule

Receives notification about a rule match. At the time that this method is called, call.rels holds the set of relational expressions which match the operands to the rule; call.rels[0] is the root expression.

Typically a rule would check that the nodes are valid matches, creates a new expression, then calls back RelOptRuleCall.transformTo(org.apache.calcite.rel.RelNode, java.util.Map<org.apache.calcite.rel.RelNode, org.apache.calcite.rel.RelNode>, org.apache.calcite.plan.RelHintsPropagator) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)