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

Packages that use Reducer

Package	Description
org.apache.hadoop.mapred
org.apache.hadoop.mapred.lib
org.apache.hadoop.mapred.lib.aggregate

Uses of Reducer in org.apache.hadoop.mapred

Methods in org.apache.hadoop.mapred that return types with arguments of type Reducer

Modifier and Type	Method and Description
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

Modifier and Type	Method and Description
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.

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

Classes in org.apache.hadoop.mapred.lib that implement Reducer

Modifier and Type	Class and Description
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

Modifier and Type	Method and Description
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

Modifier and Type	Class and Description
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.