org.eigenbase.relopt.volcano
Class VolcanoRuleMatch

java.lang.Object
  org.eigenbase.relopt.RelOptRuleCall
      org.eigenbase.relopt.volcano.VolcanoRuleCall
          org.eigenbase.relopt.volcano.VolcanoRuleMatch

 class VolcanoRuleMatch
extends VolcanoRuleCall

A match of a rule to a particular set of target relational expressions, frozen in time.

Since:

Jun 14, 2003

Version:

$Id: //open/dev/farrago/src/org/eigenbase/relopt/volcano/VolcanoRuleMatch.java#2 $

Author:

jhyde

Field Summary

private double	cachedImportance
private String	digest
private RelSet	targetSet
private RelSubset	targetSubset
private VolcanoPlanner	volcanoPlanner

Fields inherited from class org.eigenbase.relopt.RelOptRuleCall

rels, tracer

Constructor Summary

VolcanoRuleMatch(VolcanoPlanner volcanoPlanner, RelOptRuleOperand operand0, RelNode[] rels)
Creates a VolcanoRuleMatch.

Method Summary

(package private) void	clearCachedImportance() Clears the cached importance value of this rule match.
private String	computeDigest() Computes a string describing this rule match.
(package private) double	computeImportance() Computes the importance of this rule match.
(package private) double	getImportance() Returns the importance of this rule.
private RelSubset	guessSubset() Returns a guess as to which subset (that is equivalence class of relational expressions combined with a set of physical traits) the result of this rule will belong to.
void	recomputeDigest() Recomputes the digest of this VolcanoRuleMatch.
String	toString()

Methods inherited from class org.eigenbase.relopt.volcano.VolcanoRuleCall

match, onMatch, transformTo

Methods inherited from class org.eigenbase.relopt.RelOptRuleCall

getChildRels, getOperand0, getParents, getPlanner, getRels, getRule

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, wait, wait, wait

Field Detail

targetSet

private final RelSet targetSet

targetSubset

private RelSubset targetSubset

digest

private String digest

volcanoPlanner

private final VolcanoPlanner volcanoPlanner

cachedImportance

private double cachedImportance

Constructor Detail

VolcanoRuleMatch

VolcanoRuleMatch(VolcanoPlanner volcanoPlanner,
                 RelOptRuleOperand operand0,
                 RelNode[] rels)

Creates a VolcanoRuleMatch.

Parameters:

operand0 - Primary operand

rels - List of targets; copied by the constructor, so the client can modify it later

"Precondition:"

rels[i] != null

Method Detail

toString

public String toString()

Overrides:

toString in class Object

clearCachedImportance

void clearCachedImportance()

Clears the cached importance value of this rule match. The importance will be re-calculated next time getImportance() is called.

getImportance

double getImportance()

Returns the importance of this rule.

Calls computeImportance() the first time, thereafter uses a cached value until clearCachedImportance() is called.

Returns:

importance of this rule; a value between 0 and 1

computeImportance

double computeImportance()

Computes the importance of this rule match.

Returns:

importance of this rule match

computeDigest

private String computeDigest()

Computes a string describing this rule match. Two rule matches are equivalent if and only if their digests are the same.

Returns:

description of this rule match

recomputeDigest

public void recomputeDigest()

Recomputes the digest of this VolcanoRuleMatch. It is necessary when sets have merged since the match was created.

guessSubset

private RelSubset guessSubset()

Returns a guess as to which subset (that is equivalence class of relational expressions combined with a set of physical traits) the result of this rule will belong to.

Returns:

expected subset, or null if we cannot guess