oracle.spatial.hadoop.vector.join.mapreduce

Class JoinReducer

java.lang.Object

org.apache.hadoop.mapreduce.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

oracle.spatial.hadoop.vector.join.mapreduce.JoinReducer

public class JoinReducer
extends org.apache.hadoop.mapreduce.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Processes groups of records from two different data sets that belong to the same partition and determines which pair of records meet the spatial interaction defined in the job's SpatialOperationConfig.
Each reducer task is meant to process all the records for one partition which are expected to be grouped using JoinGroupGroupComparator and the values should be sorted using JoinGroupKeyComparator.
The output value is a text in JSON format containing a pair of records (each record from a different data set), which met the spatial interaction defined.
As the same records may lay in more than one partition, duplicates may exist so JoinOutputCommitter can be used to removed those duplicated joins.

Nested Class Summary

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

org.apache.hadoop.mapreduce.Reducer.Context

Constructor Summary

Constructors

Constructor and Description
JoinReducer()

Method Summary

Modifier and Type	Method and Description
protected void	cleanup(org.apache.hadoop.mapreduce.Reducer.Context context)
protected void	reduce(JoinGroupWritable key, java.lang.Iterable<RecordInfo> values, org.apache.hadoop.mapreduce.Reducer.Context context)
protected 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

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

Constructor Detail

JoinReducer

public JoinReducer()

Method Detail

setup

protected void setup(org.apache.hadoop.mapreduce.Reducer.Context context)
              throws java.io.IOException,
                     java.lang.InterruptedException

Overrides:

setup in class org.apache.hadoop.mapreduce.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException

java.lang.InterruptedException

cleanup

protected void cleanup(org.apache.hadoop.mapreduce.Reducer.Context context)
                throws java.io.IOException,
                       java.lang.InterruptedException

Overrides:

cleanup in class org.apache.hadoop.mapreduce.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException

java.lang.InterruptedException

reduce

protected void reduce(JoinGroupWritable key,
                      java.lang.Iterable<RecordInfo> values,
                      org.apache.hadoop.mapreduce.Reducer.Context context)
               throws java.io.IOException,
                      java.lang.InterruptedException

Overrides:

reduce in class org.apache.hadoop.mapreduce.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException

java.lang.InterruptedException