org.apache.hadoop.mapred.lib
Class HashPartitioner

java.lang.Object
  org.apache.hadoop.mapred.lib.HashPartitioner

All Implemented Interfaces:

JobConfigurable, Partitioner

public class HashPartitioner
extends Object
implements Partitioner

Partition keys by their Object.hashCode().

Constructor Summary

HashPartitioner()

Method Summary

void	configure(JobConf job) Initializes a new instance from a JobConf.
int	getPartition(WritableComparable key, Writable 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

configure

public void configure(JobConf job)

Description copied from interface: JobConfigurable

Initializes a new instance from a JobConf.

Specified by:

configure in interface JobConfigurable

Parameters:

job - the configuration

getPartition

public int getPartition(WritableComparable key,
                        Writable value,
                        int numReduceTasks)

Use Object.hashCode() to partition.

Specified by:

getPartition in interface Partitioner

Parameters:

key - the entry key

value - the entry value

numReduceTasks - the number of partitions

Returns:

the partition number