Package org.apache.calcite.plan.volcano

Class RelSet

java.lang.Object

org.apache.calcite.plan.volcano.RelSet

class RelSet
extends java.lang.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.

Field Summary

Fields

Modifier and Type	Field	Description
(package private) java.util.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.
private static org.slf4j.Logger	LOGGER
(package private) java.util.List<RelNode>	parents	Relational expressions that have a subset in this set as a child.
(package private) RelNode	rel
(package private) java.util.List<RelNode>	rels
(package private) java.util.List<RelSubset>	subsets
(package private) java.util.Set<CorrelationId>	variablesPropagated	Variables that are set by relational expressions in this set and available for use by parent and child expressions.
(package private) java.util.Set<CorrelationId>	variablesUsed	Variables that are used by relational expressions in this set.

Constructor Summary

Constructors

Constructor	Description
RelSet(int id, java.util.Set<CorrelationId> variablesPropagated, java.util.Set<CorrelationId> variablesUsed)

Method Summary

Modifier and Type	Method	Description
RelSubset	add(RelNode rel)	Adds a relational expression to a set, with its results available under a particular calling convention.
private void	addAbstractConverters(VolcanoPlanner planner, RelOptCluster cluster, RelSubset subset, boolean subsetToOthers)
(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)
java.util.List<RelNode>	getParentRels()	Returns all of the RelNodes which reference RelNodes in this set.
java.util.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)	Removes all references to a specific RelNode in both the subsets and their parent relationships.
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

LOGGER

private static final org.slf4j.Logger LOGGER

rels

final java.util.List<RelNode> rels

parents

final java.util.List<RelNode> parents

Relational expressions that have a subset in this set as a child. This is a multi-set. If multiple relational expressions in this set have the same parent, there will be multiple entries.

subsets

final java.util.List<RelSubset> subsets

abstractConverters

final java.util.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

final java.util.Set<CorrelationId> variablesPropagated

Variables that are set by relational expressions in this set and available for use by parent and child expressions.

variablesUsed

final java.util.Set<CorrelationId> variablesUsed

Variables that are used by relational expressions in this set.

id

final int id

inMetadataQuery

boolean inMetadataQuery

Reentrancy flag.

Constructor Detail

RelSet

RelSet(int id,
       java.util.Set<CorrelationId> variablesPropagated,
       java.util.Set<CorrelationId> variablesUsed)

Method Detail

getParentRels

public java.util.List<RelNode> getParentRels()

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

getRelsFromAllSubsets

public java.util.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)

Removes all references to a specific RelNode in both the subsets and their parent relationships.

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).

addAbstractConverters

private void addAbstractConverters(VolcanoPlanner planner,
                                   RelOptCluster cluster,
                                   RelSubset subset,
                                   boolean subsetToOthers)

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.apache.calcite.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