org.eigenbase.rel.rules
Class PushProjectPastJoinRule

java.lang.Object
  org.eigenbase.relopt.RelOptRule
      org.eigenbase.rel.rules.PushProjectPastJoinRule

public class PushProjectPastJoinRule
extends RelOptRule

PushProjectPastJoinRule implements the rule for pushing a projection past a join by splitting the projection into a projection on top of each child of the join.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/PushProjectPastJoinRule.java#17 $

Author:

Zelaine Fong

Field Summary

static PushProjectPastJoinRule	instance
private PushProjector.ExprCondition	preserveExprCondition Condition for expressions that should be preserved in the projection.

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private	PushProjectPastJoinRule() Creates a PushProjectPastJoinRule.
	PushProjectPastJoinRule(PushProjector.ExprCondition preserveExprCondition) Creates a PushProjectPastJoinRule with an explicit condition.

Method Summary

void	onMatch(RelOptRuleCall call) Receives notification about a rule match.

Methods inherited from class org.eigenbase.relopt.RelOptRule

convert, equals, equals, getOperand, getOperands, getOutConvention, getOutTrait, hashCode, matches, mergeTraitsAndConvert, mergeTraitsAndConvert, toString

Methods inherited from class java.lang.Object

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

Field Detail

instance

public static final PushProjectPastJoinRule instance

preserveExprCondition

private final PushProjector.ExprCondition preserveExprCondition

Condition for expressions that should be preserved in the projection.

Constructor Detail

PushProjectPastJoinRule

private PushProjectPastJoinRule()

Creates a PushProjectPastJoinRule.

PushProjectPastJoinRule

public PushProjectPastJoinRule(PushProjector.ExprCondition preserveExprCondition)

Creates a PushProjectPastJoinRule with an explicit condition.

Parameters:

preserveExprCondition - Condition for expressions that should be preserved in the projection

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.eigenbase.rel.RelNode) to register the expression.

Specified by:

onMatch in class RelOptRule

Parameters:

call - Rule call

See Also:

RelOptRule.matches(RelOptRuleCall)