HRegionPartitioner (Apache HBase 1.1.7 API)

java.lang.Object
- org.apache.hadoop.mapreduce.Partitioner<ImmutableBytesWritable,VALUE>
- - org.apache.hadoop.hbase.mapreduce.HRegionPartitioner<KEY,VALUE>

Type Parameters:
KEY - The type of the key.
VALUE - The type of the value.

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable
```
@InterfaceAudience.Public
@InterfaceStability.Stable
public class HRegionPartitioner<KEY,VALUE>
extends org.apache.hadoop.mapreduce.Partitioner<ImmutableBytesWritable,VALUE>
implements org.apache.hadoop.conf.Configurable
```
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()

Constructors
Constructor and Description
`HRegionPartitioner()`

Method Summary

Methods
Modifier and Type	Method and Description
`org.apache.hadoop.conf.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(org.apache.hadoop.conf.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.
    
    Specified by:
    
    getPartition in class org.apache.hadoop.mapreduce.Partitioner<ImmutableBytesWritable,VALUE>
    
    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:
    Partitioner.getPartition( java.lang.Object, java.lang.Object, int)
  - getConf
```
public org.apache.hadoop.conf.Configuration getConf()
```
    Returns the current configuration.
    
    Specified by:
    
    getConf in interface org.apache.hadoop.conf.Configurable
    
    Returns:
    The current configuration.
    See Also:
    Configurable.getConf()
  - setConf
```
public void setConf(org.apache.hadoop.conf.Configuration configuration)
```
    Sets the configuration. This is used to determine the start keys for the given table.
    
    Specified by:
    
    setConf in interface org.apache.hadoop.conf.Configurable
    
    Parameters:
    configuration - The configuration to set.
    See Also:
    Configurable.setConf( org.apache.hadoop.conf.Configuration)

Class HRegionPartitioner<KEY,VALUE>

Constructor Summary

Method Summary

Methods inherited from class java.lang.Object

Constructor Detail

HRegionPartitioner

Method Detail

getPartition

getConf

setConf