接口 org.apache.hadoop.mapred.Partitioner
的使用

使用Partitioner的程序包

程序包	说明
org.apache.hadoop.contrib.index.mapred
org.apache.hadoop.examples	Hadoop example code.
org.apache.hadoop.mapred	A software framework for easily writing applications which process vast amounts of data (multi-terabyte data-sets) parallelly on large clusters (thousands of nodes) built of commodity hardware in a reliable, fault-tolerant manner.
org.apache.hadoop.mapred.lib	Library of generally useful mappers, reducers, and partitioners.

org.apache.hadoop.contrib.index.mapred中Partitioner的使用

实现Partitioner的org.apache.hadoop.contrib.index.mapred中的类

限定符和类型	类和说明
class	IndexUpdatePartitioner This partitioner class puts the values of the same key - in this case the same shard - in the same partition.

org.apache.hadoop.examples中Partitioner的使用

实现Partitioner的org.apache.hadoop.examples中的类

限定符和类型	类和说明
class	SleepJob Dummy class for testing MR framefork.

org.apache.hadoop.mapred中Partitioner的使用

返回变量类型为Partitioner的类型的org.apache.hadoop.mapred中的方法

限定符和类型	方法和说明
Class<? extends Partitioner>	JobConf.getPartitionerClass() Get the Partitioner used to partition Mapper-outputs to be sent to the Reducers.

参数类型为Partitioner的org.apache.hadoop.mapred中的方法

限定符和类型	方法和说明
static <K extends WritableComparable,V extends Writable> Writable	MapFileOutputFormat.getEntry(MapFile.Reader[] readers, Partitioner<K,V> partitioner, K key, V value) Get an entry from output generated by this class.

类型变量类型为Partitioner的org.apache.hadoop.mapred中的方法参数

限定符和类型	方法和说明
void	JobConf.setPartitionerClass(Class<? extends Partitioner> theClass) Set the Partitioner class used to partition Mapper-outputs to be sent to the Reducers.

org.apache.hadoop.mapred.lib中Partitioner的使用

实现Partitioner的org.apache.hadoop.mapred.lib中的类

限定符和类型	类和说明
class	BinaryPartitioner<V> Partition BinaryComparable keys using a configurable part of the bytes array returned by BinaryComparable.getBytes().
class	HashPartitioner<K2,V2> Partition keys by their Object.hashCode().
class	KeyFieldBasedPartitioner<K2,V2> Defines a way to partition keys based on certain key fields (also see KeyFieldBasedComparator.
class	TotalOrderPartitioner<K extends WritableComparable,V> Partitioner effecting a total order by reading split points from an externally generated source.