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

java.lang.Object
org.apache.hadoop.mapred.MapReduceBase
oracle.hadoop.balancer.examples.invindx.InvertedIndexMapred.InvertedIndexReducer

All Implemented Interfaces:

java.io.Closeable, org.apache.hadoop.mapred.JobConfigurable, org.apache.hadoop.mapred.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Enclosing class:

InvertedIndexMapred

public static class InvertedIndexMapred.InvertedIndexReducer

extends org.apache.hadoop.mapred.MapReduceBase

implements org.apache.hadoop.mapred.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

The inverted index reducer class for mapred API

Constructor Summary

InvertedIndexMapred.InvertedIndexReducer()

Method Summary

void	configure(org.apache.hadoop.mapred.JobConf job)
void	reduce(InvertedIndex.InvertedIndexKey key, java.util.Iterator<InvertedIndex.InvertedIndexValue> values, org.apache.hadoop.mapred.OutputCollector<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text> collector, org.apache.hadoop.mapred.Reporter reporter) The reduce function.

Methods inherited from class org.apache.hadoop.mapred.MapReduceBase

close

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.io.Closeable

close

Constructor Detail

InvertedIndexMapred.InvertedIndexReducer

public InvertedIndexMapred.InvertedIndexReducer()

Method Detail

configure

public void configure(org.apache.hadoop.mapred.JobConf job)

Specified by:

configure in interface org.apache.hadoop.mapred.JobConfigurable

Overrides:

configure in class org.apache.hadoop.mapred.MapReduceBase

reduce

public void reduce(InvertedIndex.InvertedIndexKey key,
                   java.util.Iterator<InvertedIndex.InvertedIndexValue> values,
                   org.apache.hadoop.mapred.OutputCollector<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text> collector,
                   org.apache.hadoop.mapred.Reporter reporter)
            throws java.io.IOException

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.

Specified by:

reduce in interface org.apache.hadoop.mapred.Reducer<InvertedIndex.InvertedIndexKey,InvertedIndex.InvertedIndexValue,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException

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