org.apache.hadoop.mapreduce.lib.partition
Class HashPartitioner<K,V>

java.lang.Object
  extended by org.apache.hadoop.mapreduce.Partitioner<K,V>
      extended by org.apache.hadoop.mapreduce.lib.partition.HashPartitioner<K,V>

public class HashPartitioner<K,V>
extends Partitioner<K,V>

Partition keys by their Object.hashCode().


Constructor Summary
HashPartitioner()
           
 
Method Summary
 int getPartition(K key, V value, int numReduceTasks)
          Use Object.hashCode() to partition.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

HashPartitioner

public HashPartitioner()
Method Detail

getPartition

public int getPartition(K key,
                        V value,
                        int numReduceTasks)
Use Object.hashCode() to partition.

Specified by:
getPartition in class Partitioner<K,V>
Parameters:
key - the key to be partioned.
value - the entry value.
numReduceTasks - the total number of partitions.
Returns:
the partition number for the key.


Copyright © 2009 The Apache Software Foundation