datafu.pig.bags
Class EmptyBagToNullFields

java.lang.Object
  org.apache.pig.EvalFunc<T>
      datafu.pig.util.ContextualEvalFunc<org.apache.pig.data.DataBag>
          datafu.pig.bags.EmptyBagToNullFields

public class EmptyBagToNullFields
extends ContextualEvalFunc<org.apache.pig.data.DataBag>

For an empty bag, inserts a tuple having null values for all fields; otherwise, the input bag is returned unchanged.

This can be useful when performing FLATTEN on a bag from a COGROUP, as FLATTEN on an empty bag produces no data.

Field Summary

Fields inherited from class org.apache.pig.EvalFunc

log, pigLogger, reporter, returnType

Constructor Summary

EmptyBagToNullFields()

Method Summary

org.apache.pig.data.DataBag	exec(org.apache.pig.data.Tuple tuple)
org.apache.pig.impl.logicalLayer.schema.Schema	outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Methods inherited from class datafu.pig.util.ContextualEvalFunc

getContextProperties, getInstanceName, getInstanceProperties, setUDFContextSignature

Methods inherited from class org.apache.pig.EvalFunc

finish, getArgToFuncMapping, getCacheFiles, getInputSchema, getLogger, getPigLogger, getReporter, getReturnType, getSchemaName, isAsynchronous, progress, setInputSchema, setPigLogger, setReporter, warn

Methods inherited from class java.lang.Object

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

Constructor Detail

EmptyBagToNullFields

public EmptyBagToNullFields()

Method Detail

exec

public org.apache.pig.data.DataBag exec(org.apache.pig.data.Tuple tuple)
                                 throws java.io.IOException

Specified by:

exec in class org.apache.pig.EvalFunc<org.apache.pig.data.DataBag>

Throws:

java.io.IOException

outputSchema

public org.apache.pig.impl.logicalLayer.schema.Schema outputSchema(org.apache.pig.impl.logicalLayer.schema.Schema input)

Overrides:

outputSchema in class org.apache.pig.EvalFunc<org.apache.pig.data.DataBag>