Book Image

Hadoop Beginner's Guide

Book Image

Hadoop Beginner's Guide

Overview of this book

Data is arriving faster than you can process it and the overall volumes keep growing at a rate that keeps you awake at night. Hadoop can help you tame the data beast. Effective use of Hadoop however requires a mixture of programming, design, and system administration skills."Hadoop Beginner's Guide" removes the mystery from Hadoop, presenting Hadoop and related technologies with a focus on building working systems and getting the job done, using cloud services to do so when it makes sense. From basic concepts and initial setup through developing applications and keeping the system running as the data grows, the book gives the understanding needed to effectively use Hadoop to solve real world problems.Starting with the basics of installing and configuring Hadoop, the book explains how to develop applications, maintain the system, and how to use additional products to integrate with other systems.While learning different ways to develop applications to run on Hadoop the book also covers tools such as Hive, Sqoop, and Flume that show how Hadoop can be integrated with relational databases and log collection.In addition to examples on Hadoop clusters on Ubuntu uses of cloud services such as Amazon, EC2 and Elastic MapReduce are covered.
Table of Contents (19 chapters)
Hadoop Beginner's Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
Index

Time for action – reduce-side join using MultipleInputs


We can perform the report explained in the previous section using a reduce-side join by performing the following steps:

  1. Create the following tab-separated file and name it sales.txt:

    00135.992012-03-15
    00212.492004-07-02
    00413.422005-12-20
    003499.992010-12-20
    00178.952012-04-02
    00221.992006-11-30
    00293.452008-09-10
    0019.992012-05-17
  2. Create the following tab-separated file and name it accounts.txt:

    001John AllenStandard2012-03-15
    002Abigail SmithPremium2004-07-13
    003April StevensStandard2010-12-20
    004Nasser HafezPremium2001-04-23
  3. Copy the datafiles onto HDFS.

    $ hadoop fs -mkdir sales
    $ hadoop fs -put sales.txt sales/sales.txt
    $ hadoop fs -mkdir accounts
    $ hadoop fs -put accounts/accounts.txt
    
  4. Create the following file and name it ReduceJoin.java:

    import java.io.* ;
    
    import org.apache.hadoop.conf.Configuration;
    import org.apache.hadoop.fs.Path;
    import org.apache.hadoop.io.Text;
    import org.apache.hadoop.mapreduce.*;
    import org.apache.hadoop.mapreduce...