org.apache.hadoop.contrib.utils.join
Class TaggedMapOutput

java.lang.Object
  extended by org.apache.hadoop.contrib.utils.join.TaggedMapOutput
All Implemented Interfaces:
Writable

public abstract class TaggedMapOutput
extends Object
implements Writable

This abstract class serves as the base class for the values that flow from the mappers to the reducers in a data join job. Typically, in such a job, the mappers will compute the source tag of an input record based on its attributes or based on the file name of the input file. This tag will be used by the reducers to re-group the values of a given key according to their source tags.


Field Summary
protected  Text tag
           
 
Constructor Summary
TaggedMapOutput()
           
 
Method Summary
 TaggedMapOutput clone(JobConf job)
           
abstract  Writable getData()
           
 Text getTag()
           
 void setTag(Text tag)
           
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 
Methods inherited from interface org.apache.hadoop.io.Writable
readFields, write
 

Field Detail

tag

protected Text tag
Constructor Detail

TaggedMapOutput

public TaggedMapOutput()
Method Detail

getTag

public Text getTag()

setTag

public void setTag(Text tag)

getData

public abstract Writable getData()

clone

public TaggedMapOutput clone(JobConf job)


Copyright © 2009 The Apache Software Foundation