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

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.POSplit

All Implemented Interfaces:

Serializable, Cloneable, Comparable<Operator>, Illustrable

public class POSplit
extends PhysicalOperator

The MapReduce Split operator.

The assumption here is that the logical to physical translation will create this dummy operator with just the filename using which the input branch will be stored and used for loading Also the translation should make sure that appropriate filter operators are configured as outputs of this operator using the conditions specified in the LOSplit. So LOSplit will be converted into: | | | Filter1 Filter2 ... Filter3 | | ... | | | ... | ---- POSplit -... ---- This is different than the existing implementation where the POSplit writes to sidefiles after filtering and then loads the appropriate file.

The approach followed here is as good as the old approach if not better in many cases because of the availability of attachinInputs. An optimization that can ensue is if there are multiple loads that load the same file, they can be merged into one and then the operators that take input from the load can be stored. This can be used when the mapPlan executes to read the file only once and attach the resulting tuple as inputs to all the operators that take input from this load. In some cases where the conditions are exclusive and some outputs are ignored, this approach can be worse. But this leads to easier management of the Split and also allows to reuse this data stored from the split job whenever necessary.

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

POSplit(OperatorKey k)
Constructs an operator with the specified key

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

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

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

Method Summary

void	addPlan(PhysicalPlan inPlan) Appends the specified plan to the end of the nested input plan list
Result	getNextTuple()
List<PhysicalPlan>	getPlans() Returns the list of nested plans.
FileSpec	getSplitStore() Returns the name of the file associated with this operator
Tuple	illustratorMarkup(Object in, Object out, int eqClassIndex) input tuple mark up to be illustrate-able
String	name()
void	removePlan(PhysicalPlan plan) Removes plan from the nested input plan list
void	setSplitStore(FileSpec splitStore) Sets the name of the file associated with this operator
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

POSplit

public POSplit(OperatorKey k)

Constructs an operator with the specified key

Parameters:

k - the operator key

POSplit

public POSplit(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

POSplit

public POSplit(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

POSplit

public POSplit(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.

getSplitStore

public FileSpec getSplitStore()

Returns the name of the file associated with this operator

Returns:

the FileSpec associated with this operator

setSplitStore

public void setSplitStore(FileSpec splitStore)

Sets the name of the file associated with this operator

Parameters:

splitStore - the FileSpec used to store the data

getPlans

public List<PhysicalPlan> getPlans()

Returns the list of nested plans.

Returns:

the list of the nested plans

See Also:

PlanPrinter

addPlan

public void addPlan(PhysicalPlan inPlan)

Appends the specified plan to the end of the nested input plan list

Parameters:

inPlan - plan to be appended to the list

removePlan

public void removePlan(PhysicalPlan plan)

Removes plan from the nested input plan list

Parameters:

plan - plan to be removed

getNextTuple

public Result getNextTuple()
                    throws ExecException

Overrides:

getNextTuple in class PhysicalOperator

Throws:

ExecException

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