org.apache.hadoop.mapreduce.lib.partition

クラス BinaryPartitioner<V>

java.lang.Object

org.apache.hadoop.mapreduce.Partitioner<BinaryComparable,V>

org.apache.hadoop.mapreduce.lib.partition.BinaryPartitioner<V>

すべての実装されたインタフェース:

Configurable

直系の既知のサブクラス:

BinaryPartitioner

@InterfaceAudience.Public
 @InterfaceStability.Evolving
public class BinaryPartitioner<V>
extends Partitioner<BinaryComparable,V>
implements Configurable

Partition BinaryComparable keys using a configurable part of the bytes array returned by BinaryComparable.getBytes().

The subarray to be used for the partitioning can be defined by means of the following properties:

• mapreduce.partition.binarypartitioner.left.offset: left offset in array (0 by default)
• mapreduce.partition.binarypartitioner.right.offset: right offset in array (-1 by default)

Like in Python, both negative and positive offsets are allowed, but the meaning is slightly different. In case of an array of length 5, for instance, the possible offsets are:

  +---+---+---+---+---+
  | B | B | B | B | B |
  +---+---+---+---+---+
    0   1   2   3   4
   -5  -4  -3  -2  -1
 

The first row of numbers gives the position of the offsets 0...5 in the array; the second row gives the corresponding negative offsets. Contrary to Python, the specified subarray has byte i and j as first and last element, repectively, when i and j are the left and right offset.

For Hadoop programs written in Java, it is advisable to use one of the following static convenience methods for setting the offsets:

• setOffsets(org.apache.hadoop.conf.Configuration, int, int)
• setLeftOffset(org.apache.hadoop.conf.Configuration, int)
• setRightOffset(org.apache.hadoop.conf.Configuration, int)

フィールドのサマリー

フィールド

修飾子とタイプ	フィールドと説明
static String	LEFT_OFFSET_PROPERTY_NAME
static String	RIGHT_OFFSET_PROPERTY_NAME

コンストラクタのサマリー

コンストラクタ

コンストラクタと説明
BinaryPartitioner()

メソッドのサマリー

修飾子とタイプ	メソッドと説明
Configuration	getConf() Return the configuration used by this object.
int	getPartition(BinaryComparable key, V value, int numPartitions) Use (the specified slice of the array returned by) BinaryComparable.getBytes() to partition.
void	setConf(Configuration conf) Set the configuration to be used by this object.
static void	setLeftOffset(Configuration conf, int offset) Set the subarray to be used for partitioning to bytes[offset:] in Python syntax.
static void	setOffsets(Configuration conf, int left, int right) Set the subarray to be used for partitioning to bytes[left:(right+1)] in Python syntax.
static void	setRightOffset(Configuration conf, int offset) Set the subarray to be used for partitioning to bytes[:(offset+1)] in Python syntax.

クラスから継承されたメソッド java.lang.Object

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

フィールドの詳細

LEFT_OFFSET_PROPERTY_NAME

public static final String LEFT_OFFSET_PROPERTY_NAME

関連項目:

定数フィールド値

RIGHT_OFFSET_PROPERTY_NAME

public static final String RIGHT_OFFSET_PROPERTY_NAME

関連項目:

定数フィールド値

コンストラクタの詳細

BinaryPartitioner

public BinaryPartitioner()

メソッドの詳細

setOffsets

public static void setOffsets(Configuration conf,
                              int left,
                              int right)

Set the subarray to be used for partitioning to bytes[left:(right+1)] in Python syntax.

パラメータ:

conf - configuration object

left - left Python-style offset

right - right Python-style offset

setLeftOffset

public static void setLeftOffset(Configuration conf,
                                 int offset)

Set the subarray to be used for partitioning to bytes[offset:] in Python syntax.

パラメータ:

conf - configuration object

offset - left Python-style offset

setRightOffset

public static void setRightOffset(Configuration conf,
                                  int offset)

Set the subarray to be used for partitioning to bytes[:(offset+1)] in Python syntax.

パラメータ:

conf - configuration object

offset - right Python-style offset

setConf

public void setConf(Configuration conf)

インタフェースからコピーされた説明: Configurable

Set the configuration to be used by this object.

定義:

setConf インタフェース内 Configurable

getConf

public Configuration getConf()

インタフェースからコピーされた説明: Configurable

Return the configuration used by this object.

定義:

getConf インタフェース内 Configurable

getPartition

public int getPartition(BinaryComparable key,
                        V value,
                        int numPartitions)

Use (the specified slice of the array returned by) BinaryComparable.getBytes() to partition.

定義:

getPartition クラス内 Partitioner<BinaryComparable,V>

パラメータ:

key - the key to be partioned.

value - the entry value.

numPartitions - the total number of partitions.

戻り値:

the partition number for the key.