org.apache.hadoop.mapred.lib
Class IdentityReducer

java.lang.Object
  org.apache.hadoop.mapred.MapReduceBase
      org.apache.hadoop.mapred.lib.IdentityReducer

All Implemented Interfaces:

Closeable, JobConfigurable, Reducer

public class IdentityReducer
extends MapReduceBase
implements Reducer

Performs no reduction, writing all input values directly to the output.

Constructor Summary

IdentityReducer()

Method Summary

void	reduce(WritableComparable key, Iterator values, OutputCollector output, Reporter reporter) Writes all keys and values directly to output.

Methods inherited from class org.apache.hadoop.mapred.MapReduceBase

close, configure

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.mapred.JobConfigurable

configure

Methods inherited from interface org.apache.hadoop.io.Closeable

close

Constructor Detail

IdentityReducer

public IdentityReducer()

Method Detail

reduce

public void reduce(WritableComparable key,
                   Iterator values,
                   OutputCollector output,
                   Reporter reporter)
            throws IOException

Writes all keys and values directly to output.

Specified by:

reduce in interface Reducer

Parameters:

key - the key

values - the values to combine

output - to collect combined values

Throws:

IOException