net.sf.saffron.rel
Class CorrelatorRel

java.lang.Object
  |
  +--net.sf.saffron.rel.SaffronRel
        |
        +--net.sf.saffron.rel.JoinRel
              |
              +--net.sf.saffron.rel.CorrelatorRel

public class CorrelatorRel

extends JoinRel

A CorrelatorRel behaves like a kind of JoinRel, but works by setting variables in its environment and restarting its right-hand input. It is used to represent a correlated query; one implementation option is to de-correlate the expression.

Since:

23 September, 2001

Version:

$Id: //open/saffron/src/net/sf/saffron/rel/CorrelatorRel.java#3 $

Author:

jhyde

Nested Class Summary

Nested classes inherited from class net.sf.saffron.rel.JoinRel

JoinRel.JoinType

Field Summary

(package private) Expression[]

correlations

Fields inherited from class net.sf.saffron.rel.JoinRel

condition, joinType, left, right, variablesStopped

Fields inherited from class net.sf.saffron.rel.SaffronRel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

(package private)

CorrelatorRel(VolcanoCluster cluster, SaffronRel left, SaffronRel right, int joinType, Expression[] correlations) Creates a Correlator.

Method Summary

Object

clone()

Methods inherited from class net.sf.saffron.rel.JoinRel

childrenAccept, deriveRowType, explain, getChildExps, getCondition, getInputs, getJoinType, getLeft, getRight, getVariablesStopped, registerStoppedVariable, replaceInput, setVariablesStopped, switchJoinType

Methods inherited from class net.sf.saffron.rel.SaffronRel

computeDigest, computeSelfCost, getCluster, getConvention, getCorrelVariable, getId, getInput, getOrCreateCorrelVariable, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getTable, implement, implementFieldAccess, isAccessTo, isDistinct, 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

Expression[] correlations

Constructor Detail

CorrelatorRel

CorrelatorRel(VolcanoCluster cluster,
              SaffronRel left,
              SaffronRel right,
              int joinType,
              Expression[] correlations)

Creates a Correlator.

Parameters:

cluster - VolcanoCluster this relational expression belongs to

left - left input relational expression

right - right input relational expression

joinType - join type (see JoinRel.joinType)

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

Method Detail

clone

public Object clone()

Overrides:

clone in class JoinRel