| クラス | 説明 | 
|---|---|
| BinaryPartitioner<V> | Partition  BinaryComparablekeys using a configurable part of 
 the bytes array returned byBinaryComparable.getBytes(). | 
| ChainMapper | The ChainMapper class allows to use multiple Mapper classes within a single
 Map task. | 
| ChainReducer | The ChainReducer class allows to chain multiple Mapper classes after a
 Reducer within the Reducer task. | 
| CombineFileInputFormat<K,V> | An abstract  InputFormatthat returnsCombineFileSplit's
 inInputFormat.getSplits(JobConf, int)method. | 
| CombineFileRecordReader<K,V> | A generic RecordReader that can hand out different recordReaders
 for each chunk in a  CombineFileSplit. | 
| CombineFileRecordReaderWrapper<K,V> | A wrapper class for a record reader that handles a single file split. | 
| CombineFileSplit | |
| CombineSequenceFileInputFormat<K,V> | Input format that is a  CombineFileInputFormat-equivalent forSequenceFileInputFormat. | 
| CombineTextInputFormat | Input format that is a  CombineFileInputFormat-equivalent forTextInputFormat. | 
| FieldSelectionMapReduce<K,V> | This class implements a mapper/reducer class that can be used to perform
 field selections in a manner similar to unix cut. | 
| FilterOutputFormat<K,V> | FilterOutputFormat is a convenience class that wraps OutputFormat. | 
| HashPartitioner<K2,V2> | Partition keys by their  Object.hashCode(). | 
| IdentityMapper<K,V> | Implements the identity function, mapping inputs directly to outputs. | 
| IdentityReducer<K,V> | Performs no reduction, writing all input values directly to the output. | 
| InputSampler<K,V> | |
| InverseMapper<K,V> | A  Mapperthat swaps keys and values. | 
| KeyFieldBasedComparator<K,V> | This comparator implementation provides a subset of the features provided
 by the Unix/GNU Sort. | 
| KeyFieldBasedPartitioner<K2,V2> | Defines a way to partition keys based on certain key fields (also see
   KeyFieldBasedComparator. | 
| LazyOutputFormat<K,V> | A Convenience class that creates output lazily. | 
| LongSumReducer<K> | A  Reducerthat sums long values. | 
| MultipleInputs | This class supports MapReduce jobs that have multiple input paths with
 a different  InputFormatandMapperfor each path | 
| MultipleOutputFormat<K,V> | This abstract class extends the FileOutputFormat, allowing to write the
 output data to different output files. | 
| MultipleOutputs | The MultipleOutputs class simplifies writting to additional outputs other
 than the job default output via the  OutputCollectorpassed to
 themap()andreduce()methods of theMapperandReducerimplementations. | 
| MultipleSequenceFileOutputFormat<K,V> | This class extends the MultipleOutputFormat, allowing to write the output data 
 to different output files in sequence file output format. | 
| MultipleTextOutputFormat<K,V> | This class extends the MultipleOutputFormat, allowing to write the output
 data to different output files in Text output format. | 
| MultithreadedMapRunner<K1,V1,K2,V2> | Multithreaded implementation for  MapRunnable. | 
| NLineInputFormat | NLineInputFormat which splits N lines of input as one split. | 
| NullOutputFormat<K,V> | Consume all outputs and put them in /dev/null. | 
| RegexMapper<K> | A  Mapperthat extracts text matching a regular expression. | 
| TokenCountMapper<K> | A  Mapperthat maps text values into <token,freq> pairs. | 
| TotalOrderPartitioner<K,V> | Partitioner effecting a total order by reading split points from
 an externally generated source. | 
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