org.eigenbase.sql2rel
Class RelDecorrelator

java.lang.Object
  org.eigenbase.sql2rel.RelDecorrelator

All Implemented Interfaces:

ReflectiveVisitor

public class RelDecorrelator
extends Object
implements ReflectiveVisitor

RelDecorrelator replaces all correlated expressions(corExp) in a relational expression (RelNode) tree with non-correlated expressions that are produced from joining the RelNode that produces the corExp with the RelNode that references it.

Version:

$Id: //open/dev/farrago/src/org/eigenbase/sql2rel/RelDecorrelator.java#22 $

Author:

Rushan Chen

Nested Class Summary

private class	RelDecorrelator.AdjustProjectForCountAggregateRule
private class	RelDecorrelator.DecorrelateRelVisitor
private class	RelDecorrelator.DecorrelateRexShuttle
private class	RelDecorrelator.RemoveCorrelationForScalarAggregateRule
private class	RelDecorrelator.RemoveCorrelationForScalarProjectRule
private class	RelDecorrelator.RemoveCorrelationRexShuttle
private class	RelDecorrelator.RemoveSingleAggregateRule Rule to remove single_value rel.

Field Summary

private RelNode	currentRel
private RelDecorrelator.DecorrelateRelVisitor	decorrelateVisitor
private HashSet<CorrelatorRel>	generatedCorRels
private SortedMap<CorrelatorRel.Correlation,CorrelatorRel>	mapCorVarToCorRel
private Map<RexFieldAccess,CorrelatorRel.Correlation>	mapFieldAccessToCorVar
private Map<RelNode,SortedMap<CorrelatorRel.Correlation,Integer>>	mapNewRelToMapCorVarToOutputPos
private Map<RelNode,Map<Integer,Integer>>	mapNewRelToMapOldToNewOutputPos
private Map<RelNode,RelNode>	mapOldToNewRel
private Map<RelNode,SortedSet<CorrelatorRel.Correlation>>	mapRefRelToCorVar
private RexBuilder	rexBuilder
private static Logger	sqlToRelTracer

Constructor Summary

RelDecorrelator(RexBuilder rexBuilder, Map<RelNode,SortedSet<CorrelatorRel.Correlation>> mapRefRelToCorVar, SortedMap<CorrelatorRel.Correlation,CorrelatorRel> mapCorVarToCorRel, Map<RexFieldAccess,CorrelatorRel.Correlation> mapFieldAccessToCorVar)

Method Summary

private RelNode	aggregateCorrelatorOutput(CorrelatorRel corRel, ProjectRel projRel, Set<Integer> isCount) Pulls projRel above the joinRel from its RHS input.
private boolean	checkCorVars(CorrelatorRel corRel, ProjectRel projRel, FilterRel filterRel, List<RexFieldAccess> correlatedJoinKeys) Checks whether the correlations in projRel and filterRel are related to the correlated variables provided by corRel.
private RelNode	createProjectWithAdditionalExprs(RelNode childRel, RexNode[] additionalExprs, String[] additionalExprNames) Project all childRel output fields plus the additional expressions.
private RelNode	createValueGenerator(SortedSet<CorrelatorRel.Correlation> correlations, int valueGenFieldOffset, SortedMap<CorrelatorRel.Correlation,Integer> mapCorVarToOutputPos) Create RelNode tree that produces a list of correlated variables.
RelNode	decorrelate(RelNode root)
protected RexNode	decorrelateExpr(RexNode exp)
private void	decorrelateInputWithValueGenerator(RelNode rel)
void	decorrelateRel(AggregateRel rel) Rewrite AggregateRel.
void	decorrelateRel(CorrelatorRel rel) Rewrite CorrelatorRel into a left outer join.
void	decorrelateRel(FilterRel rel) Rewrite FilterRel.
void	decorrelateRel(JoinRel rel) Rewrite JoinRel.
void	decorrelateRel(ProjectRel rel) Rewrite ProjectRel.
void	decorrelateRel(SortRel rel) Rewrite SortRel.
void	decorrelateRelGeneric(RelNode rel)
private RexInputRef	getNewForOldInputRef(RexInputRef oldInputRef)
private RelNode	projectJoinOutputWithNullability(JoinRel joinRel, ProjectRel projRel, int nullIndicatorPos) Pull projRel above the joinRel from its RHS input.
protected RexNode	removeCorrelationExpr(RexNode exp, boolean projectPulledAboveLeftCorrelator)
protected RexNode	removeCorrelationExpr(RexNode exp, boolean projectPulledAboveLeftCorrelator, RexInputRef nullIndicator)
protected RexNode	removeCorrelationExpr(RexNode exp, boolean projectPulledAboveLeftCorrelator, Set<Integer> isCount)
RelNode	removeCorrelationViaRule(RelNode root)
private void	removeCorVarFromTree(CorrelatorRel corRel) Remove correlated variables from the tree at root corRel

Methods inherited from class java.lang.Object

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

Field Detail

sqlToRelTracer

private static final Logger sqlToRelTracer

mapRefRelToCorVar

private final Map<RelNode,SortedSet<CorrelatorRel.Correlation>> mapRefRelToCorVar

mapCorVarToCorRel

private final SortedMap<CorrelatorRel.Correlation,CorrelatorRel> mapCorVarToCorRel

mapFieldAccessToCorVar

private final Map<RexFieldAccess,CorrelatorRel.Correlation> mapFieldAccessToCorVar

decorrelateVisitor

private final RelDecorrelator.DecorrelateRelVisitor decorrelateVisitor

rexBuilder

private final RexBuilder rexBuilder

currentRel

private RelNode currentRel

mapOldToNewRel

private final Map<RelNode,RelNode> mapOldToNewRel

mapNewRelToMapCorVarToOutputPos

private final Map<RelNode,SortedMap<CorrelatorRel.Correlation,Integer>> mapNewRelToMapCorVarToOutputPos

mapNewRelToMapOldToNewOutputPos

private final Map<RelNode,Map<Integer,Integer>> mapNewRelToMapOldToNewOutputPos

generatedCorRels

private final HashSet<CorrelatorRel> generatedCorRels

Constructor Detail

RelDecorrelator

public RelDecorrelator(RexBuilder rexBuilder,
                       Map<RelNode,SortedSet<CorrelatorRel.Correlation>> mapRefRelToCorVar,
                       SortedMap<CorrelatorRel.Correlation,CorrelatorRel> mapCorVarToCorRel,
                       Map<RexFieldAccess,CorrelatorRel.Correlation> mapFieldAccessToCorVar)

Method Detail

decorrelate

public RelNode decorrelate(RelNode root)

removeCorrelationViaRule

public RelNode removeCorrelationViaRule(RelNode root)

decorrelateExpr

protected RexNode decorrelateExpr(RexNode exp)

removeCorrelationExpr

protected RexNode removeCorrelationExpr(RexNode exp,
                                        boolean projectPulledAboveLeftCorrelator)

removeCorrelationExpr

protected RexNode removeCorrelationExpr(RexNode exp,
                                        boolean projectPulledAboveLeftCorrelator,
                                        RexInputRef nullIndicator)

removeCorrelationExpr

protected RexNode removeCorrelationExpr(RexNode exp,
                                        boolean projectPulledAboveLeftCorrelator,
                                        Set<Integer> isCount)

decorrelateRelGeneric

public void decorrelateRelGeneric(RelNode rel)

decorrelateRel

public void decorrelateRel(SortRel rel)

Rewrite SortRel.

Parameters:

rel - SortRel to be rewritten

decorrelateRel

public void decorrelateRel(AggregateRel rel)

Rewrite AggregateRel.

Parameters:

rel - the project rel to rewrite

decorrelateRel

public void decorrelateRel(ProjectRel rel)

Rewrite ProjectRel.

Parameters:

rel - the project rel to rewrite

createValueGenerator

private RelNode createValueGenerator(SortedSet<CorrelatorRel.Correlation> correlations,
                                     int valueGenFieldOffset,
                                     SortedMap<CorrelatorRel.Correlation,Integer> mapCorVarToOutputPos)

Create RelNode tree that produces a list of correlated variables.

Parameters:

correlations - correlated variables to generate

valueGenFieldOffset - offset in the output that generated columns will start

mapCorVarToOutputPos - output positions for the correlated variables generated

Returns:

RelNode the root of the resultant RelNode tree

decorrelateInputWithValueGenerator

private void decorrelateInputWithValueGenerator(RelNode rel)

decorrelateRel

public void decorrelateRel(FilterRel rel)

Rewrite FilterRel.

Parameters:

rel - the filter rel to rewrite

decorrelateRel

public void decorrelateRel(CorrelatorRel rel)

Rewrite CorrelatorRel into a left outer join.

Parameters:

rel - CorrelatorRel

decorrelateRel

public void decorrelateRel(JoinRel rel)

Rewrite JoinRel.

Parameters:

rel - JoinRel

getNewForOldInputRef

private RexInputRef getNewForOldInputRef(RexInputRef oldInputRef)

projectJoinOutputWithNullability

private RelNode projectJoinOutputWithNullability(JoinRel joinRel,
                                                 ProjectRel projRel,
                                                 int nullIndicatorPos)

Pull projRel above the joinRel from its RHS input. Enforce nullability for join output.

Parameters:

joinRel -

projRel - the orginal projRel as the RHS input of the join.

nullIndicatorPos -

Returns:

the subtree with the new ProjectRel at the root

aggregateCorrelatorOutput

private RelNode aggregateCorrelatorOutput(CorrelatorRel corRel,
                                          ProjectRel projRel,
                                          Set<Integer> isCount)

Pulls projRel above the joinRel from its RHS input. Enforces nullability for join output.

Parameters:

corRel - Correlator

projRel - the orginal ProjectRel as the RHS input of the join

isCount - Positions which are calls to the COUNT aggregation function

Returns:

the subtree with the new ProjectRel at the root

checkCorVars

private boolean checkCorVars(CorrelatorRel corRel,
                             ProjectRel projRel,
                             FilterRel filterRel,
                             List<RexFieldAccess> correlatedJoinKeys)

Checks whether the correlations in projRel and filterRel are related to the correlated variables provided by corRel.

Parameters:

corRel - Correlator

projRel - the orginal ProjectRel as the RHS input of the join

filterRel - Filter

correlatedJoinKeys - Correlated join keys

Returns:

true if filter and proj only references corVar provided by corRel

removeCorVarFromTree

private void removeCorVarFromTree(CorrelatorRel corRel)

Remove correlated variables from the tree at root corRel

Parameters:

corRel -

createProjectWithAdditionalExprs

private RelNode createProjectWithAdditionalExprs(RelNode childRel,
                                                 RexNode[] additionalExprs,
                                                 String[] additionalExprNames)

Project all childRel output fields plus the additional expressions.

Parameters:

childRel -

additionalExprs -

additionalExprNames -

Returns:

the new ProjectRel