Package | Description |
---|---|
org.apache.hadoop.mapred | |
org.apache.hadoop.mapred.lib | |
org.apache.hadoop.mapred.lib.aggregate |
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. |
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. |
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. |
Modifier and Type | Method and Description |
---|---|
static <K1,V1,K2,V2> |
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.
|
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.
|
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