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oracle.hadoop.balancer.examples.invindx
Class InvertedIndexMapreduce.InvertedIndexReducer

java.lang.Object
org.apache.hadoop.mapreduce.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>
oracle.hadoop.balancer.examples.invindx.InvertedIndexMapreduce.InvertedIndexReducer

Enclosing class:

InvertedIndexMapreduce

public static class InvertedIndexMapreduce.InvertedIndexReducer

extends org.apache.hadoop.mapreduce.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

The inverted index reducer class for mapreduce API

Nested Class Summary

Nested classes/interfaces inherited from class org.apache.hadoop.mapreduce.Reducer

org.apache.hadoop.mapreduce.Reducer.Context

Constructor Summary

InvertedIndexMapreduce.InvertedIndexReducer()

Method Summary

void	reduce(InvertedIndex.InvertedIndexKey key, java.lang.Iterable<InvertedIndex.InvertedIndexValue> values, org.apache.hadoop.mapreduce.Reducer.Context context) The reduce function.
void	setup(org.apache.hadoop.mapreduce.Reducer.Context context)

Methods inherited from class org.apache.hadoop.mapreduce.Reducer

run

Methods inherited from class java.lang.Object

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

Constructor Detail

InvertedIndexMapreduce.InvertedIndexReducer

public InvertedIndexMapreduce.InvertedIndexReducer()

Method Detail

reduce

public void reduce(InvertedIndex.InvertedIndexKey key,
                   java.lang.Iterable<InvertedIndex.InvertedIndexValue> values,
                   org.apache.hadoop.mapreduce.Reducer.Context context)
            throws java.io.IOException,
                   java.lang.InterruptedException

The reduce function. The output per line is:

• word <location:offset:numOccurrencesAtOffset>

Since the values per key are in sorted order, we can merge consecutive duplicate locations per word.

Overrides:

reduce in class org.apache.hadoop.mapreduce.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException

java.lang.InterruptedException

setup

public void setup(org.apache.hadoop.mapreduce.Reducer.Context context)

Overrides:

setup in class org.apache.hadoop.mapreduce.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

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