org.eigenbase.relopt.volcano
Class RelSet

java.lang.Object
  org.eigenbase.relopt.volcano.RelSet

 class RelSet
extends Object

A RelSet is an equivalence-set of expressions; that is, a set of expressions which have identical semantics. We are generally interested in using the expression which has the lowest cost.

All of the expressions in an RelSet have the same calling convention.

Since:

16 December, 2001

Version:

$Id: //open/dev/farrago/src/org/eigenbase/relopt/volcano/RelSet.java#3 $

Author:

jhyde

Field Summary

(package private) List<AbstractConverter>	abstractConverters List of AbstractConverter objects which have not yet been satisfied.
(package private) RelSet	equivalentSet Set to the superseding set when this is found to be equivalent to another set.
(package private) int	id
(package private) boolean	inMetadataQuery Reentrancy flag.
(package private) RelNode	rel
(package private) List<RelNode>	rels
(package private) List<RelSubset>	subsets
private static Logger	tracer
(package private) Set<String>	variablesPropagated Names of variables which are set by relational expressions in this set and available for use by parent and child expressions.
(package private) Set<String>	variablesUsed Names of variables which are used by relational expressions in this set.

Constructor Summary

RelSet()

Method Summary

RelSubset	add(RelNode rel) Adds a relational expression to a set, with its results available under a particular calling convention.
(package private) void	addInternal(RelNode rel) Adds an expression rel to this set, without creating a RelSubset.
(package private) RelSubset	getOrCreateSubset(RelOptCluster cluster, RelTraitSet traits)
List<RelNode>	getParentRels() Returns all of the RelNodes which reference RelNodes in this set.
List<RelNode>	getRelsFromAllSubsets()
RelSubset	getSubset(RelTraitSet traits)
(package private) void	mergeWith(VolcanoPlanner planner, RelSet otherSet) Merges otherSet into this RelSet.
(package private) void	obliterateRelNode(RelNode rel)
private void	postEquivalenceEvent(VolcanoPlanner planner, RelNode rel)

Methods inherited from class java.lang.Object

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

Field Detail

tracer

private static final Logger tracer

rels

final List<RelNode> rels

subsets

final List<RelSubset> subsets

abstractConverters

List<AbstractConverter> abstractConverters

List of AbstractConverter objects which have not yet been satisfied.

equivalentSet

RelSet equivalentSet

Set to the superseding set when this is found to be equivalent to another set.

rel

RelNode rel

variablesPropagated

Set<String> variablesPropagated

Names of variables which are set by relational expressions in this set and available for use by parent and child expressions.

variablesUsed

Set<String> variablesUsed

Names of variables which are used by relational expressions in this set.

id

int id

inMetadataQuery

boolean inMetadataQuery

Reentrancy flag.

Constructor Detail

RelSet

RelSet()

Method Detail

getParentRels

public List<RelNode> getParentRels()

Returns all of the RelNodes which reference RelNodes in this set.

getRelsFromAllSubsets

public List<RelNode> getRelsFromAllSubsets()

Returns:

all of the RelNodes contained by any subset of this set (does not include the subset objects themselves)

getSubset

public RelSubset getSubset(RelTraitSet traits)

obliterateRelNode

void obliterateRelNode(RelNode rel)

add

public RelSubset add(RelNode rel)

Adds a relational expression to a set, with its results available under a particular calling convention. An expression may be in the set several times with different calling conventions (and hence different costs).

getOrCreateSubset

RelSubset getOrCreateSubset(RelOptCluster cluster,
                            RelTraitSet traits)

postEquivalenceEvent

private void postEquivalenceEvent(VolcanoPlanner planner,
                                  RelNode rel)

addInternal

void addInternal(RelNode rel)

Adds an expression rel to this set, without creating a RelSubset. (Called only from RelSubset.add(org.eigenbase.rel.RelNode).

Parameters:

rel - Relational expression

mergeWith

void mergeWith(VolcanoPlanner planner,
               RelSet otherSet)

Merges otherSet into this RelSet.

One generally calls this method after discovering that two relational expressions are equivalent, and hence the RelSets they belong to are equivalent also.

After this method completes, otherSet is obsolete, its equivalentSet member points to this RelSet, and this RelSet is still alive.

Parameters:

planner - Planner

otherSet - RelSet which is equivalent to this one