org.apache.hadoop.mapred.lib

Class InputSampler<K,V>

java.lang.Object

org.apache.hadoop.mapred.lib.InputSampler<K,V>

All Implemented Interfaces:

org.apache.hadoop.conf.Configurable, org.apache.hadoop.util.Tool

public class InputSampler<K,V>
extends java.lang.Object
implements org.apache.hadoop.util.Tool

Utility for collecting samples and writing a partition file for TotalOrderPartitioner.

Nested Class Summary

Nested Classes

Modifier and Type	Class and Description
static class	InputSampler.IntervalSampler<K,V> Sample from s splits at regular intervals.
static class	InputSampler.RandomSampler<K,V> Sample from random points in the input.
static interface	InputSampler.Sampler<K,V> Interface to sample using an InputFormat.
static class	InputSampler.SplitSampler<K,V> Samples the first n records from s splits.

Constructor Summary

Constructors

Constructor and Description
InputSampler(JobConf conf)

Method Summary

Methods

Modifier and Type	Method and Description
org.apache.hadoop.conf.Configuration	getConf()
static void	main(java.lang.String[] args)
int	run(java.lang.String[] args) Driver for InputSampler from the command line.
void	setConf(org.apache.hadoop.conf.Configuration conf)
static <K,V> void	writePartitionFile(JobConf job, InputSampler.Sampler<K,V> sampler) Write a partition file for the given job, using the Sampler provided.

Methods inherited from class java.lang.Object

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

Constructor Detail

InputSampler

public InputSampler(JobConf conf)

Method Detail

getConf

public org.apache.hadoop.conf.Configuration getConf()

Specified by:

getConf in interface org.apache.hadoop.conf.Configurable

setConf

public void setConf(org.apache.hadoop.conf.Configuration conf)

Specified by:

setConf in interface org.apache.hadoop.conf.Configurable

writePartitionFile

public static <K,V> void writePartitionFile(JobConf job,
                            InputSampler.Sampler<K,V> sampler)
                               throws java.io.IOException

Write a partition file for the given job, using the Sampler provided. Queries the sampler for a sample keyset, sorts by the output key comparator, selects the keys for each rank, and writes to the destination returned from TotalOrderPartitioner.getPartitionFile(org.apache.hadoop.mapred.JobConf).

Throws:

java.io.IOException

run

public int run(java.lang.String[] args)
        throws java.lang.Exception

Driver for InputSampler from the command line. Configures a JobConf instance and calls writePartitionFile(org.apache.hadoop.mapred.JobConf, org.apache.hadoop.mapred.lib.InputSampler.Sampler<K, V>).

Specified by:

run in interface org.apache.hadoop.util.Tool

Throws:

java.lang.Exception

main

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

Throws:

java.lang.Exception