Package org.apache.calcite.rel.rules

Class AggregateReduceFunctionsOnGroupKeysRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

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

org.apache.calcite.rel.rules.AggregateReduceFunctionsOnGroupKeysRule

All Implemented Interfaces:

TransformationRule

@Enclosing
public class AggregateReduceFunctionsOnGroupKeysRule
extends RelRule<AggregateReduceFunctionsOnGroupKeysRule.Config>
implements TransformationRule

Planner rule that eliminates aggregate functions of GROUP BY keys.

For example, SELECT sal, max(sal) FROM emp GROUP BY sal can be simplified to SELECT sal, sal FROM emp GROUP BY sal.

Currently supports the following aggregate functions when their arguments exist in the aggregate's group set or are deterministic expressions involving only group set columns and constants:

• MAX
• MIN
• AVG
• ANY_VALUE

Note: This optimization preserves NULL semantics correctly. For aggregate functions like MAX, MIN, and ANY_VALUE, NULL values in the source columns or expressions are handled the same way before and after the transformation: nulls are ignored by the aggregation, and if all grouped values are NULL, the result is NULL.

See Also:

• CoreRules.AGGREGATE_REDUCE_FUNCTIONS_ON_GROUP_KEYS

Nested Class Summary

Nested Classes

Modifier and Type	Class	Description
static interface	AggregateReduceFunctionsOnGroupKeysRule.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	Description
protected	AggregateReduceFunctionsOnGroupKeysRule(AggregateReduceFunctionsOnGroupKeysRule.Config config)	Creates an AggregateReduceFunctionsOnGroupKeysRule.

Method Summary

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

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

any, convert, convert, 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

Constructor Details

AggregateReduceFunctionsOnGroupKeysRule

protected AggregateReduceFunctionsOnGroupKeysRule(AggregateReduceFunctionsOnGroupKeysRule.Config config)

Creates an AggregateReduceFunctionsOnGroupKeysRule.

Method Details

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)