org.terrier.structures.indexing.singlepass.hadoop
Class Inv2DirectMultiReduce

java.lang.Object
  org.terrier.utility.io.HadoopUtility.MapReduceBase<org.apache.hadoop.io.IntWritable,Wrapper<IterablePosting>,org.apache.hadoop.io.VIntWritable,Posting,Object,Object>
      org.terrier.structures.indexing.singlepass.hadoop.Inv2DirectMultiReduce

All Implemented Interfaces:

Closeable, org.apache.hadoop.mapred.JobConfigurable, org.apache.hadoop.mapred.Mapper<org.apache.hadoop.io.IntWritable,Wrapper<IterablePosting>,org.apache.hadoop.io.VIntWritable,Posting>, org.apache.hadoop.mapred.Reducer<org.apache.hadoop.io.VIntWritable,Posting,Object,Object>

public class Inv2DirectMultiReduce
extends HadoopUtility.MapReduceBase<org.apache.hadoop.io.IntWritable,Wrapper<IterablePosting>,org.apache.hadoop.io.VIntWritable,Posting,Object,Object>

This class inverts an inverted index into a direct index, making use of a single MapReduce job. On completion of the MapReduce job, the counters can be used as validation of the correct running of the job. For instance "Map input records" should equal the number of terms in the index and "Map output records" should equal the number of pointers.

Since:

3.0

Author:

Craig Macdonald

Nested Class Summary

static class	Inv2DirectMultiReduce.ByDocidPartitioner<K> Partitioner partitioning by docid
static class	Inv2DirectMultiReduce.ByDocidPartitionerPosting Partitioner partitioning by docid
static class	Inv2DirectMultiReduce.Inv2DirectMultiReduceJob This class performs contains setup for the MR job.

Field Summary

protected org.apache.hadoop.mapred.JobConf

jc

Constructor Summary

Inv2DirectMultiReduce()

Method Summary

void	close() Called at end of map or reduce task.
protected void	closeMap()
protected void	closeReduce()
void	configure(org.apache.hadoop.mapred.JobConf _jc)
protected void	configureMap()
protected void	configureReduce()
static void	invertStructure(Index index, HadoopPlugin.JobFactory jf, int numberOfReduceTasks) Performs the inversion, from "inverted" structure to "direct" structure.
static void	main(String[] args) main
void	map(org.apache.hadoop.io.IntWritable termId, Wrapper<IterablePosting> postingWrapper, org.apache.hadoop.mapred.OutputCollector<org.apache.hadoop.io.VIntWritable,Posting> collector, org.apache.hadoop.mapred.Reporter reporter) Take an iterator of postings.
void	reduce(org.apache.hadoop.io.VIntWritable _targetDocid, Iterator<Posting> documentPostings, org.apache.hadoop.mapred.OutputCollector<Object,Object> collector, org.apache.hadoop.mapred.Reporter reporter)

Methods inherited from class java.lang.Object

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

Methods inherited from interface org.apache.hadoop.mapred.JobConfigurable

configure

Methods inherited from interface java.io.Closeable

close

Field Detail

jc

protected org.apache.hadoop.mapred.JobConf jc

Constructor Detail

Inv2DirectMultiReduce

public Inv2DirectMultiReduce()

Method Detail

main

public static void main(String[] args)
                 throws Exception

main

Parameters:

args -

Throws:

Exception

invertStructure

public static void invertStructure(Index index,
                                   HadoopPlugin.JobFactory jf,
                                   int numberOfReduceTasks)
                            throws Exception

Performs the inversion, from "inverted" structure to "direct" structure.

Parameters:

index - - the index to perform the inversion on

jf - - MapReduce job factory

numberOfReduceTasks - - as it says. More is better.

Throws:

Exception

configureMap

protected void configureMap()
                     throws IOException

Throws:

IOException

map

public void map(org.apache.hadoop.io.IntWritable termId,
                Wrapper<IterablePosting> postingWrapper,
                org.apache.hadoop.mapred.OutputCollector<org.apache.hadoop.io.VIntWritable,Posting> collector,
                org.apache.hadoop.mapred.Reporter reporter)
         throws IOException

Take an iterator of postings. Each posting is inverted, and the a new posting generated

Throws:

IOException

closeMap

protected void closeMap()
                 throws IOException

Throws:

IOException

configureReduce

protected void configureReduce()
                        throws IOException

Throws:

IOException

reduce

public void reduce(org.apache.hadoop.io.VIntWritable _targetDocid,
                   Iterator<Posting> documentPostings,
                   org.apache.hadoop.mapred.OutputCollector<Object,Object> collector,
                   org.apache.hadoop.mapred.Reporter reporter)
            throws IOException

Throws:

IOException

closeReduce

protected void closeReduce()
                    throws IOException

Throws:

IOException

configure

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

Specified by:

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

close

public void close()
           throws IOException

Called at end of map or reduce task. Calls internally closeMap() or closeReduce()

Specified by:

close in interface Closeable

Throws:

IOException