Home - News ( United States | United Kingdom | Italy | Germany ) - Football scores

Showing content from https://hadoop.apache.org/docs/r1.2.1/api/org/apache/hadoop/mapred/Partitioner.html below:

Partitioner (Hadoop 1.2.1 API)

All Superinterfaces:

JobConfigurable

All Known Implementing Classes:

BinaryPartitioner, HashPartitioner, IndexUpdatePartitioner, KeyFieldBasedPartitioner, SleepJob, TotalOrderPartitioner

public interface Partitioner<K2,V2>
extends JobConfigurable

Partitions the key space.

Partitioner controls the partitioning of the keys of the intermediate map-outputs. The key (or a subset of the key) is used to derive the partition, typically by a hash function. The total number of partitions is the same as the number of reduce tasks for the job. Hence this controls which of the m reduce tasks the intermediate key (and hence the record) is sent for reduction.

See Also:

Reducer

int getPartition(K2 key,
                 V2 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.

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

Parameters:

key - the key to be paritioned.

value - the entry value.

numPartitions - the total number of partitions.

Returns:

the partition number for the key.

RetroSearch is an open source project built by @garambo | Open a GitHub Issue

Search and Browse the WWW like it's 1997 | Search results from DuckDuckGo

HTML: 3.2 | Encoding: UTF-8 | Version: 0.7.4