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

java.lang.Object
  org.apache.hadoop.mapreduce.Partitioner<K,V>
      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.