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java.lang.Objectorg.apache.hadoop.mapreduce.Partitioner<BinaryComparable,V>
org.apache.hadoop.mapreduce.lib.partition.BinaryPartitioner<V>
@InterfaceAudience.Public @InterfaceStability.Evolving public class BinaryPartitioner<V>
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:
+---+---+---+---+---+
| 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)
| Constructor Summary | |
|---|---|
BinaryPartitioner()
|
|
| Method Summary | |
|---|---|
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. |
| Methods inherited from class java.lang.Object |
|---|
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait |
| Constructor Detail |
|---|
public BinaryPartitioner()
| Method Detail |
|---|
public static void setOffsets(Configuration conf,
int left,
int right)
bytes[left:(right+1)] in Python syntax.
conf - configuration objectleft - left Python-style offsetright - right Python-style offset
public static void setLeftOffset(Configuration conf,
int offset)
bytes[offset:] in Python syntax.
conf - configuration objectoffset - left Python-style offset
public static void setRightOffset(Configuration conf,
int offset)
bytes[:(offset+1)] in Python syntax.
conf - configuration objectoffset - right Python-style offsetpublic void setConf(Configuration conf)
Configurable
setConf in interface Configurablepublic Configuration getConf()
Configurable
getConf in interface Configurable
public int getPartition(BinaryComparable key,
V value,
int numPartitions)
BinaryComparable.getBytes() to partition.
getPartition in class Partitioner<BinaryComparable,V>key - the key to be partioned.value - the entry value.numPartitions - the total number of partitions.
key.
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