org.apache.hadoop.mapred.lib.aggregate
Class ValueAggregatorCombiner<K1 extends WritableComparable,V1 extends Writable>

java.lang.Object
  extended by org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase<K1,V1>
      extended by org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorCombiner<K1,V1>
All Implemented Interfaces:
Closeable, JobConfigurable, Mapper<K1,V1,Text,Text>, Reducer<Text,Text,Text,Text>

@InterfaceAudience.Public
@InterfaceStability.Stable
public class ValueAggregatorCombiner<K1 extends WritableComparable,V1 extends Writable>
extends ValueAggregatorJobBase<K1,V1>

This class implements the generic combiner of Aggregate.


Field Summary
 
Fields inherited from class org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase
aggregatorDescriptorList
 
Constructor Summary
ValueAggregatorCombiner()
           
 
Method Summary
 void close()
          Do nothing.
 void configure(JobConf job)
          Combiner does not need to configure.
 void map(K1 arg0, V1 arg1, OutputCollector<Text,Text> arg2, Reporter arg3)
          Do nothing.
 void reduce(Text key, Iterator<Text> values, OutputCollector<Text,Text> output, Reporter reporter)
          Combines values for a given key.
 
Methods inherited from class org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase
logSpec
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

ValueAggregatorCombiner

public ValueAggregatorCombiner()
Method Detail

configure

public void configure(JobConf job)
Combiner does not need to configure.

Specified by:
configure in interface JobConfigurable
Overrides:
configure in class ValueAggregatorJobBase<K1 extends WritableComparable,V1 extends Writable>
Parameters:
job - the configuration

reduce

public void reduce(Text key,
                   Iterator<Text> values,
                   OutputCollector<Text,Text> output,
                   Reporter reporter)
            throws IOException
Combines values for a given key.

Parameters:
key - the key is expected to be a Text object, whose prefix indicates the type of aggregation to aggregate the values.
values - the values to combine
output - to collect combined values
reporter - facility to report progress.
Throws:
IOException

close

public void close()
           throws IOException
Do nothing.

Specified by:
close in interface Closeable
Overrides:
close in class ValueAggregatorJobBase<K1 extends WritableComparable,V1 extends Writable>
Throws:
IOException

map

public void map(K1 arg0,
                V1 arg1,
                OutputCollector<Text,Text> arg2,
                Reporter arg3)
         throws IOException
Do nothing. Should not be called.

Parameters:
arg0 - the input key.
arg1 - the input value.
arg2 - collects mapped keys and values.
arg3 - facility to report progress.
Throws:
IOException


Copyright © 2012 Apache Software Foundation. All Rights Reserved.