org.apache.hadoop.mapred.lib
Class HashPartitioner<K2,V2>

java.lang.Object
  extended by org.apache.hadoop.mapred.lib.HashPartitioner<K2,V2>
All Implemented Interfaces:
JobConfigurable, Partitioner<K2,V2>

public class HashPartitioner<K2,V2>
extends Object
implements Partitioner<K2,V2>

Partition keys by their Object.hashCode().


Constructor Summary
HashPartitioner()
           
 
Method Summary
 void configure(JobConf job)
          Initializes a new instance from a JobConf.
 int getPartition(K2 key, V2 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(K2 key,
                        V2 value,
                        int numReduceTasks)
Use Object.hashCode() to partition.

Specified by:
getPartition in interface Partitioner<K2,V2>
Parameters:
key - the key to be paritioned.
value - the entry value.
numReduceTasks - the total number of partitions.
Returns:
the partition number for the key.


Copyright © 2009 The Apache Software Foundation