hadoop
Class CountMinorKeys

java.lang.Object
  org.apache.hadoop.conf.Configured
      hadoop.CountMinorKeys

All Implemented Interfaces:

Configurable, Tool

public class CountMinorKeys
extends Configured
implements Tool

A simple example demonstrating how to use the Oracle NoSQL DB Hadoop oracle.kv.hadoop.KVInputFormat class to read data from NoSQL Database in a Map/Reduce job and count the number of records for each major key in the store. The map() function is passed the Key and Value for each record in the KV Store and outputs k/v pairs containing the major path components as the output key and a value of 1. The reduce step sums the values for each of the records with the same key. This M/R task is similar to the ubiquitous Hadoop Map/Reduce WordCount example. The KV Keys passed to the Map function are in the canonical format described in the javadoc for the oracle.kv.Key.toString() method. The KVInputFormat and related classes are located in the lib/kvclient.jar file so this must be included in the Hadoop classpath at runtime. The arguments to the program are the kvstore name, the helperHost:port pair and the HDFS output path. For example, if you build this class (and its subclasses) and put it into myjar.jar, you can invoke with a command similar to this:

 export HADOOP_CLASSPATH=...:KVHOME/lib/kvclient.jar
 bin/hadoop jar myjar.jar hadoop.CountMinorKeys \
            -libjars KVHOME/lib/kvclient.jar \
            mystore myhost:myport /myHDFSoutputdir
 

Nested Class Summary

static class	CountMinorKeys.Map
static class	CountMinorKeys.Reduce

Constructor Summary

CountMinorKeys()

Method Summary

static void	main(String[] args)
int	run(String[] args)

Methods inherited from class org.apache.hadoop.conf.Configured

getConf, setConf

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.conf.Configurable

getConf, setConf

Constructor Detail

CountMinorKeys

public CountMinorKeys()

Method Detail

run

public int run(String[] args)
        throws Exception

Specified by:

run in interface Tool

Throws:

Exception

main

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

Throws:

Exception