org.apache.calcite.rel.rules

Class AggregateProjectPullUpConstantsRule

java.lang.Object

org.apache.calcite.plan.RelOptRule

org.apache.calcite.rel.rules.AggregateProjectPullUpConstantsRule

public class AggregateProjectPullUpConstantsRule
extends RelOptRule

Planner rule that removes constant expressions from the group list of an LogicalAggregate.

Effect of the rule

Since the transformed relational expression has to match the original relational expression, the constants are placed in a projection above the reduced aggregate. If those constants are not used, another rule will remove them from the project.

LogicalAggregate needs its group columns to be on the prefix of its input relational expression. Therefore, if a constant is not on the trailing edge of the group list, removing it will leave a hole. In this case, the rule adds a project before the aggregate to reorder the columns, and permutes them back afterwards.

Field Summary

Fields

Modifier and Type	Field and Description
static AggregateProjectPullUpConstantsRule	INSTANCE The singleton.

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

description, operands

Method Summary

Methods

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, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, none, operand, operand, operand, operand, operand, some, toString, unordered

Methods inherited from class java.lang.Object

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

Field Detail

INSTANCE

public static final AggregateProjectPullUpConstantsRule INSTANCE

The singleton.

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>) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)