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

java.lang.Object
  extended by org.apache.hadoop.mapreduce.Mapper<K1,V1,Text,Text>
      extended by org.apache.hadoop.mapreduce.lib.aggregate.ValueAggregatorMapper<K1,V1>

@InterfaceAudience.Public
@InterfaceStability.Stable
public class ValueAggregatorMapper<K1 extends WritableComparable<?>,V1 extends Writable>
extends Mapper<K1,V1,Text,Text>

This class implements the generic mapper of Aggregate.


Constructor Summary
ValueAggregatorMapper()
           
 
Method Summary
 void map(K1 key, V1 value, org.apache.hadoop.mapreduce.Mapper.Context context)
          the map function.
 void setup(org.apache.hadoop.mapreduce.Mapper.Context context)
          Called once at the beginning of the task.
 
Methods inherited from class org.apache.hadoop.mapreduce.Mapper
cleanup, run
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ValueAggregatorMapper

public ValueAggregatorMapper()
Method Detail

setup

public void setup(org.apache.hadoop.mapreduce.Mapper.Context context)
           throws IOException,
                  InterruptedException
Description copied from class: Mapper
Called once at the beginning of the task.

Overrides:
setup in class Mapper<K1 extends WritableComparable<?>,V1 extends Writable,Text,Text>
Throws:
IOException
InterruptedException

map

public void map(K1 key,
                V1 value,
                org.apache.hadoop.mapreduce.Mapper.Context context)
         throws IOException,
                InterruptedException
the map function. It iterates through the value aggregator descriptor list to generate aggregation id/value pairs and emit them.

Overrides:
map in class Mapper<K1 extends WritableComparable<?>,V1 extends Writable,Text,Text>
Throws:
IOException
InterruptedException


Copyright © 2012 Apache Software Foundation. All Rights Reserved.