org.eigenbase.rel.rules
Class ProjectToCalcRule

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

public class ProjectToCalcRule
extends RelOptRule

Rule to convert a ProjectRel to a CalcRel

The rule does not fire if the child is a ProjectRel, FilterRel or CalcRel. If it did, then the same CalcRel would be formed via several transformation paths, which is a waste of effort.

Since:

Mar 7, 2004

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/rules/ProjectToCalcRule.java#1 $

Author:

jhyde

See Also:

FilterToCalcRule

Field Summary

static ProjectToCalcRule

instance

Fields inherited from class org.eigenbase.relopt.RelOptRule

ANY, description, operands

Constructor Summary

private

ProjectToCalcRule()

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 ProjectToCalcRule instance

Constructor Detail

ProjectToCalcRule

private ProjectToCalcRule()

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)