org.apache.hadoop.mapred.lib.aggregate
Class ValueAggregatorCombiner

java.lang.Object
  org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase
      org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorCombiner

All Implemented Interfaces:

Closeable, JobConfigurable, Mapper, Reducer

public class ValueAggregatorCombiner
extends ValueAggregatorJobBase

This class implements the generic combiner of Abacus.

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(WritableComparable arg0, Writable arg1, OutputCollector arg2, Reporter arg3) Do nothing.
void	reduce(WritableComparable key, Iterator values, OutputCollector 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

Parameters:

job - the configuration

reduce

public void reduce(WritableComparable key,
                   Iterator values,
                   OutputCollector 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

Throws:

IOException

close

public void close()
           throws IOException

Do nothing.

Specified by:

close in interface Closeable

Overrides:

close in class ValueAggregatorJobBase

Throws:

IOException

map

public void map(WritableComparable arg0,
                Writable arg1,
                OutputCollector arg2,
                Reporter arg3)
         throws IOException

Do nothing. Should not be called.

Parameters:

arg0 - the key

arg1 - the values

arg2 - collects mapped keys and values

Throws:

IOException