net.sf.saffron.rel
Class DistinctRel

java.lang.Object
  |
  +--net.sf.saffron.rel.SaffronRel
        |
        +--net.sf.saffron.rel.SingleRel
              |
              +--net.sf.saffron.rel.DistinctRel

Direct Known Subclasses:

JavaDistinctRel, JavaExistsRel

public class DistinctRel

extends SingleRel

DistinctRel is a SaffronRel which eliminates duplicates from its input.

Since:

30 September, 2001

Version:

$Id: //open/saffron/src/net/sf/saffron/rel/DistinctRel.java#5 $

Author:

jhyde

Field Summary

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

child

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

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

DistinctRel(VolcanoCluster cluster, SaffronRel child)

Method Summary

Object	clone()
PlanCost	computeSelfCost(SaffronPlanner planner) Returns the cost of this plan (not including children).
boolean	isDistinct() Returns whether the same value will not come out twice.

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

childrenAccept, deriveRowType, explain, getInputs, getRows, replaceInput

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

computeDigest, getChildExps, getCluster, getConvention, getCorrelVariable, getId, getInput, getOrCreateCorrelVariable, getQualifier, getQuery, getRelTypeName, getRowType, getTable, getVariablesStopped, implement, implementFieldAccess, isAccessTo, onRegister, recomputeDigest, register, registerCorrelVariable, setCorrelVariable, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

DistinctRel

public DistinctRel(VolcanoCluster cluster,
                   SaffronRel child)

Method Detail

isDistinct

public boolean isDistinct()

Description copied from class: SaffronRel

Returns whether the same value will not come out twice. Default value is false, derived classes should override.

Overrides:

isDistinct in class SaffronRel

clone

public Object clone()

Specified by:

clone in class SaffronRel

computeSelfCost

public PlanCost computeSelfCost(SaffronPlanner planner)

Description copied from class: SaffronRel

Returns the cost of this plan (not including children). The base implementation throws an error; derived classes should override.

Overrides:

computeSelfCost in class SaffronRel