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

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

All Implemented Interfaces:

Closeable, JobConfigurable, Mapper, Reducer

public class ValueAggregatorMapper
extends ValueAggregatorJobBase

This class implements the generic mapper of Abacus.

Field Summary

Fields inherited from class org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase

aggregatorDescriptorList

Constructor Summary

ValueAggregatorMapper()

Method Summary

void	map(WritableComparable key, Writable value, OutputCollector output, Reporter reporter) the map function.
void	reduce(WritableComparable arg0, Iterator arg1, OutputCollector arg2, Reporter arg3) Do nothing.

Methods inherited from class org.apache.hadoop.mapred.lib.aggregate.ValueAggregatorJobBase

close, configure, logSpec

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ValueAggregatorMapper

public ValueAggregatorMapper()

Method Detail

map

public void map(WritableComparable key,
                Writable value,
                OutputCollector output,
                Reporter reporter)
         throws IOException

the map function. It iterates through the value aggregator descriptor list to generate aggregation id/value pairs and emit them.

Parameters:

key - the key

value - the values

output - collects mapped keys and values

Throws:

IOException

reduce

public void reduce(WritableComparable arg0,
                   Iterator arg1,
                   OutputCollector arg2,
                   Reporter arg3)
            throws IOException

Do nothing. Should not be called.

Parameters:

arg0 - the key

arg1 - the values to combine

arg2 - to collect combined values

Throws:

IOException