org.apache.hadoop.hbase.mapred
Class IndexTableReduce

java.lang.Object
  extended by org.apache.hadoop.mapred.MapReduceBase
      extended by org.apache.hadoop.hbase.mapred.IndexTableReduce
All Implemented Interfaces:
Closeable, JobConfigurable, Reducer<Text,MapWritable,Text,org.apache.hadoop.hbase.mapred.LuceneDocumentWrapper>

public class IndexTableReduce
extends MapReduceBase
implements Reducer<Text,MapWritable,Text,org.apache.hadoop.hbase.mapred.LuceneDocumentWrapper>

Construct a Lucene document per row, which is consumed by IndexOutputFormat to build a Lucene index


Constructor Summary
IndexTableReduce()
           
 
Method Summary
 void close()
          Default implementation that does nothing.
 void configure(JobConf job)
          Default implementation that does nothing.
 void reduce(Text key, Iterator<MapWritable> values, OutputCollector<Text,org.apache.hadoop.hbase.mapred.LuceneDocumentWrapper> output, Reporter reporter)
          Reduces values for a given key.
 
Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait
 

Constructor Detail

IndexTableReduce

public IndexTableReduce()
Method Detail

configure

public void configure(JobConf job)
Description copied from class: MapReduceBase
Default implementation that does nothing.

Specified by:
configure in interface JobConfigurable
Overrides:
configure in class MapReduceBase
Parameters:
job - the configuration

close

public void close()
           throws IOException
Description copied from class: MapReduceBase
Default implementation that does nothing.

Specified by:
close in interface Closeable
Overrides:
close in class MapReduceBase
Throws:
IOException

reduce

public void reduce(Text key,
                   Iterator<MapWritable> values,
                   OutputCollector<Text,org.apache.hadoop.hbase.mapred.LuceneDocumentWrapper> output,
                   Reporter reporter)
            throws IOException
Description copied from interface: Reducer
Reduces values for a given key.

The framework calls this method for each <key, (list of values)> pair in the grouped inputs. Output values must be of the same type as input values. Input keys must not be altered. Typically all values are combined into zero or one value.

Output pairs are collected with calls to OutputCollector.collect(WritableComparable,Writable).

Applications can use the Reporter provided to report progress or just indicate that they are alive. In scenarios where the application takes an insignificant amount of time to process individual key/value pairs, this is crucial since the framework might assume that the task has timed-out and kill that task. The other way of avoiding this is to set mapred.task.timeout to a high-enough value (or even zero for no time-outs).

Specified by:
reduce in interface Reducer<Text,MapWritable,Text,org.apache.hadoop.hbase.mapred.LuceneDocumentWrapper>
Parameters:
key - the key.
values - the list of values to reduce.
output - to collect keys and combined values.
reporter - facility to report progress.
Throws:
IOException


Copyright © 2006 The Apache Software Foundation