org.apache.hadoop.mapreduce.lib.aggregate
Class ValueAggregatorCombiner<K1 extends org.apache.hadoop.io.WritableComparable<?>,V1 extends org.apache.hadoop.io.Writable>

java.lang.Object
  org.apache.hadoop.mapreduce.Reducer<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>
      org.apache.hadoop.mapreduce.lib.aggregate.ValueAggregatorCombiner<K1,V1>

@InterfaceAudience.Public
@InterfaceStability.Stable
public class ValueAggregatorCombiner<K1 extends org.apache.hadoop.io.WritableComparable<?>,V1 extends org.apache.hadoop.io.Writable>
extends Reducer<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

This class implements the generic combiner of Aggregate.

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Reducer

Reducer.Context

Constructor Summary

ValueAggregatorCombiner()

Method Summary

void	reduce(org.apache.hadoop.io.Text key, Iterable<org.apache.hadoop.io.Text> values, Reducer.Context context) Combines values for a given key.

Methods inherited from class org.apache.hadoop.mapreduce.Reducer

cleanup, run, setup

Methods inherited from class java.lang.Object

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

Constructor Detail

ValueAggregatorCombiner

public ValueAggregatorCombiner()

Method Detail

reduce

public void reduce(org.apache.hadoop.io.Text key,
                   Iterable<org.apache.hadoop.io.Text> values,
                   Reducer.Context context)
            throws IOException,
                   InterruptedException

Combines values for a given key.

Overrides:

reduce in class Reducer<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Parameters:

key - the key is expected to be a Text object, whose prefix indicates the type of aggregation to aggregate the values.

values - the values to combine

context - to collect combined values

Throws:

IOException

InterruptedException