oracle.spatial.hadoop.vector.join.mapred

Class JoinReducer

java.lang.Object

org.apache.hadoop.mapred.MapReduceBase

oracle.spatial.hadoop.vector.join.mapred.JoinReducer

All Implemented Interfaces:

java.io.Closeable, java.lang.AutoCloseable, org.apache.hadoop.mapred.JobConfigurable, org.apache.hadoop.mapred.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

public class JoinReducer
extends org.apache.hadoop.mapred.MapReduceBase
implements org.apache.hadoop.mapred.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.

Constructor Summary

Constructors

Constructor and Description
JoinReducer()

Method Summary

Methods

Modifier and Type	Method and Description
void	configure(org.apache.hadoop.mapred.JobConf jobConf)
void	reduce(JoinGroupWritable key, java.util.Iterator<RecordInfo> values, org.apache.hadoop.mapred.OutputCollector<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text> output, org.apache.hadoop.mapred.Reporter reporter)

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

close

Methods inherited from class java.lang.Object

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

Methods inherited from interface java.io.Closeable

close

Constructor Detail

JoinReducer

public JoinReducer()

Method Detail

configure

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

Specified by:

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

Overrides:

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

reduce

public void reduce(JoinGroupWritable key,
          java.util.Iterator<RecordInfo> values,
          org.apache.hadoop.mapred.OutputCollector<org.apache.hadoop.io.Text,org.apache.hadoop.io.Text> output,
          org.apache.hadoop.mapred.Reporter reporter)
            throws java.io.IOException

Specified by:

reduce in interface org.apache.hadoop.mapred.Reducer<JoinGroupWritable,RecordInfo,org.apache.hadoop.io.Text,org.apache.hadoop.io.Text>

Throws:

java.io.IOException