org.eigenbase.rel.rules
Class RemoveSemiJoinRule

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

public class RemoveSemiJoinRule
extends RelOptRule

RemoveSemiJoinRule implements the rule that removes semijoins from a join tree if it turns out it's not possible to convert a SemiJoinRel to an indexed scan on a join factor. Namely, if the join factor does not reduce to a single table that can be scanned using an index. This rule should only be applied after attempts have been made to convert SemiJoinRels.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/RemoveSemiJoinRule.java#9 $

Author:

Zelaine Fong

Field Summary

static RemoveSemiJoinRule

instance

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

RemoveSemiJoinRule() Creates a RemoveSemiJoinRule.

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 RemoveSemiJoinRule instance

Constructor Detail

RemoveSemiJoinRule

private RemoveSemiJoinRule()

Creates a RemoveSemiJoinRule.

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)