saffron.rel
Class Distinct

java.lang.Object
  |
  +--saffron.rel.Rel
        |
        +--saffron.rel.SingleRel
              |
              +--saffron.rel.Distinct

Direct Known Subclasses:

JavaDistinct, JavaExists

public class Distinct

extends SingleRel

Distinct is a Rel which eliminates duplicates from its input.

Since:

30 September, 2001

Version:

$Id: //open/saffron/src/main/saffron/rel/Distinct.java#5 $

Author:

jhyde

Nested Class Summary

private static class

Distinct.ConvertDistinctToJavaRule

Nested classes inherited from class saffron.rel.Rel

Field Summary

Fields inherited from class saffron.rel.SingleRel

child

Fields inherited from class saffron.rel.Rel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

Distinct(Cluster cluster, Rel child)

Method Summary

Object	clone()
Cost	computeSelfCost(Planner planner) Returns the cost of this plan (not including children).
boolean	isDistinct() Returns whether the same value will not come out twice.
static void	register(Planner planner) See Rel.register(saffron.Planner).

Methods inherited from class saffron.rel.SingleRel

childrenAccept, deriveRowType, explain, getInputs, replaceInput

Methods inherited from class saffron.rel.Rel

computeDigest, getChildExps, getCluster, getConvention, getCorelVariable, getEnvironment, getId, getInput, getOrCreateCorelVariable, getParentEnv, getQualifier, getQuery, getRelTypeName, getRows, getRowType, getTable, getType, getVariablesStopped, implement, implementExp, implementExps, implementFieldAccess, implementSelf, isAccessTo, onRegister, recomputeDigest, registerCorelVariable, setCorelVariable, toString

Methods inherited from class java.lang.Object

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

Constructor Detail

Distinct

public Distinct(Cluster cluster,
                Rel child)

Method Detail

clone

public Object clone()

Specified by:

clone in class Rel

isDistinct

public boolean isDistinct()

Description copied from class: Rel

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

Overrides:

isDistinct in class Rel

computeSelfCost

public Cost computeSelfCost(Planner planner)

Description copied from class: Rel

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

Overrides:

computeSelfCost in class Rel

register

public static void register(Planner planner)

See Rel.register(saffron.Planner).