org.apache.calcite.sql2rel

Class RelDecorrelator

java.lang.Object

org.apache.calcite.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.

TODO:

• replace CorelMap constructor parameter with a RelNode
• make currentRel immutable (would require a fresh RelDecorrelator for each node being decorrelated)
• make fields of CorelMap immutable
• make sub-class rules static, and have them create their own de-correlator

Method Summary

Methods

Modifier and Type	Method and Description
protected RexNode	decorrelateExpr(RexNode exp)
static RelNode	decorrelateQuery(RelNode rootRel) Decorrelates a query.
void	decorrelateRel(LogicalAggregate rel) Rewrites a LogicalAggregate.
void	decorrelateRel(LogicalCorrelate rel) Rewrite Correlator into a left outer join.
void	decorrelateRel(LogicalFilter rel) Rewrite LogicalFilter.
void	decorrelateRel(LogicalJoin rel) Rewrite LogicalJoin.
void	decorrelateRel(LogicalProject rel) Rewrite LogicalProject.
void	decorrelateRel(Sort rel) Rewrite Sort.
void	decorrelateRelGeneric(RelNode rel)
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)

Methods inherited from class java.lang.Object

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

Method Detail

decorrelateQuery

public static RelNode decorrelateQuery(RelNode rootRel)

Decorrelates a query.

This is the main entry point to RelDecorrelator.

Parameters:

rootRel - Root node of the query

Returns:

Equivalent query with all LogicalCorrelate instances removed

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(Sort rel)

Rewrite Sort.

Parameters:

rel - Sort to be rewritten

decorrelateRel

public void decorrelateRel(LogicalAggregate rel)

Rewrites a LogicalAggregate.

Parameters:

rel - Aggregate to rewrite

decorrelateRel

public void decorrelateRel(LogicalProject rel)

Rewrite LogicalProject.

Parameters:

rel - the project rel to rewrite

decorrelateRel

public void decorrelateRel(LogicalFilter rel)

Rewrite LogicalFilter.

Parameters:

rel - the filter rel to rewrite

decorrelateRel

public void decorrelateRel(LogicalCorrelate rel)

Rewrite Correlator into a left outer join.

Parameters:

rel - Correlator

decorrelateRel

public void decorrelateRel(LogicalJoin rel)

Rewrite LogicalJoin.

Parameters:

rel - LogicalJoin