org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators
Class PODemux

java.lang.Object
  org.apache.pig.impl.plan.Operator<PhyPlanVisitor>
      org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator
          org.apache.pig.backend.hadoop.executionengine.physicalLayer.relationalOperators.PODemux

All Implemented Interfaces:

Serializable, Cloneable, Comparable<Operator>, Illustrable

public class PODemux
extends PhysicalOperator

The MapReduce Demultiplexer operator.

This operator is used when merging multiple Map-Reduce splittees into a Map-only splitter during multi-query optimization. The reduce physical plans of the splittees become the inner plans of this operator.

Due to the recursive nature of multi-query optimization, this operator may be contained in another demux operator.

The predecessor of this operator must be a POMultiQueryPackage operator which passes the index (indicating which inner reduce plan to run) along with other data to this operator.

See Also:

Serialized Form

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator

PhysicalOperator.OriginalLocation

Field Summary

Fields inherited from class org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator

alias, illustrator, input, inputAttached, inputs, lineageTracer, outputs, parentPlan, pigLogger, requestedParallelism, res, resultType

Fields inherited from class org.apache.pig.impl.plan.Operator

mKey

Constructor Summary

PODemux(OperatorKey k)
Constructs an operator with the specified key.

PODemux(OperatorKey k, int rp)
Constructs an operator with the specified key and degree of parallelism.

PODemux(OperatorKey k, int rp, List<PhysicalOperator> inp)
Constructs an operator with the specified key, degree of parallelism and inputs.

PODemux(OperatorKey k, List<PhysicalOperator> inp)
Constructs an operator with the specified key and inputs.

Method Summary

void	addPlan(PhysicalPlan inPlan) Appends the specified plan at the end of the list.
Result	getNextTuple()
List<PhysicalPlan>	getPlans() Returns the list of inner plans.
Tuple	illustratorMarkup(Object in, Object out, int eqClassIndex) input tuple mark up to be illustrate-able
boolean	isInCombiner() Returns a flag indicating if this operator is in a combiner.
String	name()
void	setInCombiner(boolean inCombiner) Sets a flag indicating if this operator is in a combiner.
boolean	supportsMultipleInputs() Indicates whether this operator supports multiple inputs.
boolean	supportsMultipleOutputs() Indicates whether this operator supports multiple outputs.
void	visit(PhyPlanVisitor v) Visit this node with the provided visitor.

Methods inherited from class org.apache.pig.backend.hadoop.executionengine.physicalLayer.PhysicalOperator

addOriginalLocation, addOriginalLocation, attachInput, clone, cloneHelper, detachInput, getAlias, getAliasString, getIllustrator, getInputs, getLogger, getNext, getNextBigDecimal, getNextBigInteger, getNextBoolean, getNextDataBag, getNextDataByteArray, getNextDateTime, getNextDouble, getNextFloat, getNextInteger, getNextLong, getNextMap, getNextString, getOriginalLocations, getPigLogger, getReporter, getRequestedParallelism, getResultType, isAccumStarted, isAccumulative, isBlocking, isInputAttached, processInput, reset, setAccumEnd, setAccumStart, setAccumulative, setIllustrator, setInputs, setParentPlan, setPigLogger, setReporter, setRequestedParallelism, setResultType

Methods inherited from class org.apache.pig.impl.plan.Operator

compareTo, equals, getOperatorKey, getProjectionMap, hashCode, regenerateProjectionMap, rewire, toString, unsetProjectionMap

Methods inherited from class java.lang.Object

finalize, getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

PODemux

public PODemux(OperatorKey k)

Constructs an operator with the specified key.

Parameters:

k - the operator key

PODemux

public PODemux(OperatorKey k,
               int rp)

Constructs an operator with the specified key and degree of parallelism.

Parameters:

k - the operator key

rp - the degree of parallelism requested

PODemux

public PODemux(OperatorKey k,
               List<PhysicalOperator> inp)

Constructs an operator with the specified key and inputs.

Parameters:

k - the operator key

inp - the inputs that this operator will read data from

PODemux

public PODemux(OperatorKey k,
               int rp,
               List<PhysicalOperator> inp)

Constructs an operator with the specified key, degree of parallelism and inputs.

Parameters:

k - the operator key

rp - the degree of parallelism requested

inp - the inputs that this operator will read data from

Method Detail

visit

public void visit(PhyPlanVisitor v)
           throws VisitorException

Description copied from class: Operator

Visit this node with the provided visitor. This should only be called by the visitor class itself, never directly.

Specified by:

visit in class PhysicalOperator

Parameters:

v - Visitor to visit with.

Throws:

VisitorException - if the visitor has a problem.

name

public String name()

Specified by:

name in class Operator<PhyPlanVisitor>

supportsMultipleInputs

public boolean supportsMultipleInputs()

Description copied from class: Operator

Indicates whether this operator supports multiple inputs.

Specified by:

supportsMultipleInputs in class Operator<PhyPlanVisitor>

Returns:

true if it does, otherwise false.

supportsMultipleOutputs

public boolean supportsMultipleOutputs()

Description copied from class: Operator

Indicates whether this operator supports multiple outputs.

Specified by:

supportsMultipleOutputs in class Operator<PhyPlanVisitor>

Returns:

true if it does, otherwise false.

getPlans

public List<PhysicalPlan> getPlans()

Returns the list of inner plans.

Returns:

the list of the nested plans

addPlan

public void addPlan(PhysicalPlan inPlan)

Appends the specified plan at the end of the list.

Parameters:

inPlan - plan to be appended to the inner plan list

getNextTuple

public Result getNextTuple()
                    throws ExecException

Overrides:

getNextTuple in class PhysicalOperator

Throws:

ExecException

setInCombiner

public void setInCombiner(boolean inCombiner)

Sets a flag indicating if this operator is in a combiner.

Parameters:

inCombiner - true if this operator is in a combiner; false if this operator is in a reducer

isInCombiner

public boolean isInCombiner()

Returns a flag indicating if this operator is in a combiner.

Returns:

true if this operator is in a combiner; otherwise this operator is in a reducer

illustratorMarkup

public Tuple illustratorMarkup(Object in,
                               Object out,
                               int eqClassIndex)

Description copied from interface: Illustrable

input tuple mark up to be illustrate-able

Parameters:

in - input tuple

out - output tuple before wrapped in ExampleTuple

eqClassIndex - index into equivalence classes in illustrator

Returns:

tuple