saffron.rel
Class Union

java.lang.Object
  |
  +--saffron.rel.Rel
        |
        +--saffron.rel.Union

Direct Known Subclasses:

Intersect, IterConcatenate, JavaUnionAll, Minus

public class Union

extends Rel

Union returns the union of the rows of its inputs, optionally eliminating duplicates.

Since:

23 September, 2001

Version:

$Id: //open/saffron/src/main/saffron/rel/Union.java#6 $

Author:

jhyde

Nested Class Summary

private static class	Union.ConvertToIteratorRule Rule to converts a Union to iterator calling convention.
private static class	Union.ConvertToJavaRule Rule to converts a Union to Java calling convention.

Nested classes inherited from class saffron.rel.Rel

Field Summary

protected boolean	all
protected Rel[]	inputs

Fields inherited from class saffron.rel.Rel

cluster, digest, emptyArray, id, nextId, rowType

Constructor Summary

Union(Cluster cluster, Rel[] inputs, boolean all)

Method Summary

Object	clone()
protected Type	deriveRowType()
void	explain(PlanWriter pw)
Rel[]	getInputs() Returns an array of this Rel's inputs.
double	getRows() Returns an estimate of the number of rows this relational expression will return.
boolean	isDistinct() Returns whether the same value will not come out twice.
static void	register(Planner planner) See Rel.register(saffron.Planner).
void	replaceInput(int ordinalInParent, Rel p) Replaces the ordinalInParentth input.

Methods inherited from class saffron.rel.Rel

childrenAccept, computeDigest, computeSelfCost, getChildExps, getCluster, getConvention, getCorelVariable, getEnvironment, getId, getInput, getOrCreateCorelVariable, getParentEnv, getQualifier, getQuery, getRelTypeName, 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

Field Detail

inputs

protected Rel[] inputs

all

protected boolean all

Constructor Detail

Union

public Union(Cluster cluster,
             Rel[] inputs,
             boolean all)

Method Detail

clone

public Object clone()

Specified by:

clone in class Rel

getInputs

public Rel[] getInputs()

Description copied from class: Rel

Returns an array of this Rel's inputs. If there are no inputs, returns an empty array, not null.

Overrides:

getInputs in class Rel

explain

public void explain(PlanWriter pw)

Overrides:

explain in class Rel

replaceInput

public void replaceInput(int ordinalInParent,
                         Rel p)

Description copied from class: Rel

Replaces the ordinalInParent^th input. You must override this method if you override Rel.getInputs().

Overrides:

replaceInput in class Rel

deriveRowType

protected Type deriveRowType()

Specified by:

deriveRowType in class Rel

getRows

public double getRows()

Description copied from class: Rel

Returns an estimate of the number of rows this relational expression will return.

Overrides:

getRows 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

register

public static void register(Planner planner)

See Rel.register(saffron.Planner).