Uses of Interface
org.apache.hadoop.mapred.Reducer

Packages that use Reducer
org.apache.hadoop.contrib.index.mapred   
org.apache.hadoop.contrib.utils.join   
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.mapred.lib.aggregate Classes for performing various counting and aggregations. 
org.apache.hadoop.streaming Hadoop Streaming is a utility which allows users to create and run Map-Reduce jobs with any executables (e.g. 
 

Uses of Reducer in org.apache.hadoop.contrib.index.mapred
 

Classes in org.apache.hadoop.contrib.index.mapred that implement Reducer
 class IndexUpdateCombiner
          This combiner combines multiple intermediate forms into one intermediate form.
 class IndexUpdateReducer
          This reducer applies to a shard the changes for it.
 

Uses of Reducer in org.apache.hadoop.contrib.utils.join
 

Classes in org.apache.hadoop.contrib.utils.join that implement Reducer
 class DataJoinMapperBase
          This abstract class serves as the base class for the mapper class of a data join job.
 class DataJoinReducerBase
          This abstract class serves as the base class for the reducer class of a data join job.
 class JobBase
          A common base implementing some statics collecting mechanisms that are commonly used in a typical map/reduce job.
 

Uses of Reducer in org.apache.hadoop.examples
 

Classes in org.apache.hadoop.examples that implement Reducer
static class PiEstimator.PiReducer
          Reducer class for Pi estimation.
 class SleepJob
          Dummy class for testing MR framefork.
 

Uses of Reducer in org.apache.hadoop.mapred
 

Methods in org.apache.hadoop.mapred that return types with arguments of type Reducer
 Class<? extends Reducer> JobConf.getCombinerClass()
          Get the user-defined combiner class used to combine map-outputs before being sent to the reducers.
 Class<? extends Reducer> JobConf.getReducerClass()
          Get the Reducer class for the job.
 

Method parameters in org.apache.hadoop.mapred with type arguments of type Reducer
 void JobConf.setCombinerClass(Class<? extends Reducer> theClass)
          Set the user-defined combiner class used to combine map-outputs before being sent to the reducers.
 void JobConf.setReducerClass(Class<? extends Reducer> theClass)
          Set the Reducer class for the job.
 

Constructor parameters in org.apache.hadoop.mapred with type arguments of type Reducer
Task.OldCombinerRunner(Class<? extends Reducer<K,V,K,V>> cls, JobConf conf, Counters.Counter inputCounter, Task.TaskReporter reporter)
           
 

Uses of Reducer in org.apache.hadoop.mapred.lib
 

Classes in org.apache.hadoop.mapred.lib that implement Reducer
 class ChainReducer
          The ChainReducer class allows to chain multiple Mapper classes after a Reducer within the Reducer task.
 class 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.
 class IdentityReducer<K,V>
          Performs no reduction, writing all input values directly to the output.
 class LongSumReducer<K>
          A Reducer that sums long values.
 

Method parameters in org.apache.hadoop.mapred.lib with type arguments of type Reducer
static
<K1,V1,K2,V2>
void
ChainReducer.setReducer(JobConf job, Class<? extends Reducer<K1,V1,K2,V2>> klass, Class<? extends K1> inputKeyClass, Class<? extends V1> inputValueClass, Class<? extends K2> outputKeyClass, Class<? extends V2> outputValueClass, boolean byValue, JobConf reducerConf)
          Sets the Reducer class to the chain job's JobConf.
 

Uses of Reducer in org.apache.hadoop.mapred.lib.aggregate
 

Classes in org.apache.hadoop.mapred.lib.aggregate that implement Reducer
 class ValueAggregatorCombiner<K1 extends WritableComparable,V1 extends Writable>
          This class implements the generic combiner of Aggregate.
 class ValueAggregatorJobBase<K1 extends WritableComparable,V1 extends Writable>
          This abstract class implements some common functionalities of the the generic mapper, reducer and combiner classes of Aggregate.
 class ValueAggregatorMapper<K1 extends WritableComparable,V1 extends Writable>
          This class implements the generic mapper of Aggregate.
 class ValueAggregatorReducer<K1 extends WritableComparable,V1 extends Writable>
          This class implements the generic reducer of Aggregate.
 

Uses of Reducer in org.apache.hadoop.streaming
 

Classes in org.apache.hadoop.streaming that implement Reducer
 class PipeCombiner
           
 class PipeReducer
          A generic Reducer bridge.
 



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