org.apache.hadoop.mapred.lib

类 TotalOrderPartitioner<K extends WritableComparable,V>

java.lang.Object

org.apache.hadoop.mapred.lib.TotalOrderPartitioner<K,V>

所有已实现的接口:

JobConfigurable, Partitioner<K,V>

public class TotalOrderPartitioner<K extends WritableComparable,V>
extends Object
implements Partitioner<K,V>

Partitioner effecting a total order by reading split points from an externally generated source.

字段概要

字段

限定符和类型	字段和说明
static String	DEFAULT_PATH

构造器概要

构造器

构造器和说明
TotalOrderPartitioner()

方法概要

方法

限定符和类型	方法和说明
void	configure(JobConf job) Read in the partition file and build indexing data structures.
int	getPartition(K key, V value, int numPartitions) Get the paritition number for a given key (hence record) given the total number of partitions i.e. number of reduce-tasks for the job.
static String	getPartitionFile(JobConf job) Get the path to the SequenceFile storing the sorted partition keyset.
static void	setPartitionFile(JobConf job, Path p) Set the path to the SequenceFile storing the sorted partition keyset.

从类继承的方法 java.lang.Object

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

字段详细资料

DEFAULT_PATH

public static final String DEFAULT_PATH

另请参阅:

常量字段值

构造器详细资料

TotalOrderPartitioner

public TotalOrderPartitioner()

方法详细资料

configure

public void configure(JobConf job)

Read in the partition file and build indexing data structures. If the keytype is BinaryComparable and total.order.partitioner.natural.order is not false, a trie of the first total.order.partitioner.max.trie.depth(2) + 1 bytes will be built. Otherwise, keys will be located using a binary search of the partition keyset using the RawComparator defined for this job. The input file must be sorted with the same comparator and contain JobConf.getNumReduceTasks() - 1 keys.

指定者:

configure 在接口中 JobConfigurable

参数:

job - the configuration

getPartition

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

从接口复制的说明: Partitioner

Get the paritition 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.

指定者:

getPartition 在接口中 Partitioner<K extends WritableComparable,V>

参数:

key - the key to be paritioned.

value - the entry value.

numPartitions - the total number of partitions.

返回:

the partition number for the key.

setPartitionFile

public static void setPartitionFile(JobConf job,
                    Path p)

Set the path to the SequenceFile storing the sorted partition keyset. It must be the case that for R reduces, there are R-1 keys in the SequenceFile.

getPartitionFile

public static String getPartitionFile(JobConf job)

Get the path to the SequenceFile storing the sorted partition keyset.

另请参阅:

setPartitionFile(JobConf,Path)