org.eigenbase.rel
Class CorrelatorRel

java.lang.Object
  org.eigenbase.rel.AbstractRelNode
      org.eigenbase.rel.JoinRelBase
          org.eigenbase.rel.CorrelatorRel

All Implemented Interfaces:

Cloneable, RelNode

public final class CorrelatorRel
extends JoinRelBase

A CorrelatorRel behaves like a kind of JoinRel, but works by setting variables in its environment and restarting its right-hand input.

A CorrelatorRel is used to represent a correlated query. One implementation strategy is to de-correlate the expression.

Since:

23 September, 2001

Version:

$Id: //open/dev/farrago/src/org/eigenbase/rel/CorrelatorRel.java#19 $

Author:

jhyde

Nested Class Summary

static class

CorrelatorRel.Correlation Describes the neccessary parameters for an implementation in order to identify and set dynamic variables

Field Summary

protected List<CorrelatorRel.Correlation>

correlations

Fields inherited from class org.eigenbase.rel.JoinRelBase

condition, joinType, left, right, variablesStopped

Fields inherited from class org.eigenbase.rel.AbstractRelNode

digest, id, nextId, rowType, traits

Fields inherited from interface org.eigenbase.rel.RelNode

emptyArray

Constructor Summary

CorrelatorRel(RelOptCluster cluster, RelNode left, RelNode right, List<CorrelatorRel.Correlation> correlations, JoinRelType joinType)
Creates a CorrelatorRel with no join condition.

CorrelatorRel(RelOptCluster cluster, RelNode left, RelNode right, RexNode joinCond, List<CorrelatorRel.Correlation> correlations, JoinRelType joinType)
Creates a CorrelatorRel.

Method Summary

CorrelatorRel	clone() Clones this RelNode.
protected RelDataType	deriveRowType()
void	explain(RelOptPlanWriter pw)
List<CorrelatorRel.Correlation>	getCorrelations() Returns the correlating expressions.

Methods inherited from class org.eigenbase.rel.JoinRelBase

_isValid, childrenAccept, computeSelfCost, createJoinType, deriveJoinRowType, estimateJoinedRows, getChildExps, getCondition, getInputs, getJoinType, getLeft, getRight, getRows, getSystemFieldList, getVariablesStopped, registerStoppedVariable, replaceInput, setVariablesStopped

Methods inherited from class org.eigenbase.rel.AbstractRelNode

cloneTraits, collectVariablesSet, collectVariablesUsed, computeDigest, getCluster, getCollationList, getConvention, getCorrelVariable, getDescription, getDigest, getExpectedInputRowType, getId, getInput, getOrCreateCorrelVariable, getQuery, getRelTypeName, getRowType, getTable, getTraits, inheritTraitsFrom, isAccessTo, isDistinct, isValid, onRegister, recomputeDigest, register, registerCorrelVariable, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Field Detail

correlations

protected final List<CorrelatorRel.Correlation> correlations

Constructor Detail

CorrelatorRel

public CorrelatorRel(RelOptCluster cluster,
                     RelNode left,
                     RelNode right,
                     RexNode joinCond,
                     List<CorrelatorRel.Correlation> correlations,
                     JoinRelType joinType)

Creates a CorrelatorRel.

Parameters:

cluster - cluster this relational expression belongs to

left - left input relational expression

right - right input relational expression

joinCond - join condition

correlations - set of expressions to set as variables each time a row arrives from the left input

joinType - join type

CorrelatorRel

public CorrelatorRel(RelOptCluster cluster,
                     RelNode left,
                     RelNode right,
                     List<CorrelatorRel.Correlation> correlations,
                     JoinRelType joinType)

Creates a CorrelatorRel with no join condition.

Parameters:

cluster - cluster this relational expression belongs to

left - left input relational expression

right - right input relational expression

correlations - set of expressions to set as variables each time a row arrives from the left input

joinType - join type

Method Detail

clone

public CorrelatorRel clone()

Description copied from interface: RelNode

Clones this RelNode.

Traits of the RelNode must be explicitly cloned, using AbstractRelNode.inheritTraitsFrom(AbstractRelNode), as the RelNode may have traits of which it has no knowledge. Example implementation:

     public MyRelNode clone()
     {
         MyRelNode clone = new MyRelNode(...);
         clone.inheritTraitsFrom(this);
         return clone;
     }
 

N.B.: This method must be overridden whenever an existing, concrete RelNode is extended. Otherwise, calling clone() will produce a differently typed RelNode, resulting in invalid or incorrect query plans.

Specified by:

clone in interface RelNode

Specified by:

clone in class AbstractRelNode

Returns:

a clone of this RelNode

deriveRowType

protected RelDataType deriveRowType()

Overrides:

deriveRowType in class JoinRelBase

explain

public void explain(RelOptPlanWriter pw)

Specified by:

explain in interface RelNode

Overrides:

explain in class JoinRelBase

getCorrelations

public List<CorrelatorRel.Correlation> getCorrelations()

Returns the correlating expressions.

Returns:

correlating expressions