org.eigenbase.rel.rules
Class AddRedundantSemiJoinRule

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

public class AddRedundantSemiJoinRule
extends RelOptRule

Rule to add a semijoin into a joinrel. Transformation is as follows:

JoinRel(X, Y) -> JoinRel(SemiJoinRel(X, Y), Y)

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/AddRedundantSemiJoinRule.java#10 $

Author:

Zelaine Fong

Field Summary

static AddRedundantSemiJoinRule

instance

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

AddRedundantSemiJoinRule() Creates an AddRedundantSemiJoinRule.

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 AddRedundantSemiJoinRule instance

Constructor Detail

AddRedundantSemiJoinRule

private AddRedundantSemiJoinRule()

Creates an AddRedundantSemiJoinRule.

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)