org.apache.hadoop.hbase.mapreduce

Class HRegionPartitioner<KEY,VALUE>

java.lang.Object

<any>

org.apache.hadoop.hbase.mapreduce.HRegionPartitioner<KEY,VALUE>

Type Parameters:

KEY - The type of the key.

VALUE - The type of the value.

@InterfaceAudience.Public
 @InterfaceStability.Stable
public class HRegionPartitioner<KEY,VALUE>
extends <any>

This is used to partition the output keys into groups of keys. Keys are grouped according to the regions that currently exist so that each reducer fills a single region so load is distributed.

This class is not suitable as partitioner creating hfiles for incremental bulk loads as region spread will likely change between time of hfile creation and load time. See LoadIncrementalHFiles and Bulk Load.

Constructor Summary

Constructors

Constructor and Description
HRegionPartitioner()

Method Summary

Modifier and Type	Method and Description
Configuration	getConf() Returns the current configuration.
int	getPartition(ImmutableBytesWritable key, VALUE value, int numPartitions) Gets the partition number for a given key (hence record) given the total number of partitions i.e.
void	setConf(Configuration configuration) Sets the configuration.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

HRegionPartitioner

public HRegionPartitioner()

Method Detail

getPartition

public int getPartition(ImmutableBytesWritable key,
                        VALUE value,
                        int numPartitions)

Gets the partition number for a given key (hence record) given the total number of partitions i.e. number of reduce-tasks for the job.

Typically a hash function on a all or a subset of the key.

Parameters:

key - The key to be partitioned.

value - The entry value.

numPartitions - The total number of partitions.

Returns:

The partition number for the key.

See Also:

org.apache.hadoop.mapreduce.Partitioner#getPartition( java.lang.Object, java.lang.Object, int)

getConf

public Configuration getConf()

Returns the current configuration.

Returns:

The current configuration.

See Also:

org.apache.hadoop.conf.Configurable#getConf()

setConf

public void setConf(Configuration configuration)

Sets the configuration. This is used to determine the start keys for the given table.

Parameters:

configuration - The configuration to set.

See Also:

org.apache.hadoop.conf.Configurable#setConf( org.apache.hadoop.conf.Configuration)