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Hadoop Beginner's Guide

You're reading from   Hadoop Beginner's Guide Get your mountain of data under control with Hadoop. This guide requires no prior knowledge of the software or cloud services ‚Äì just a willingness to learn the basics from this practical step-by-step tutorial.

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Product type Paperback
Published in Feb 2013
Publisher Packt
ISBN-13 9781849517300
Length 398 pages
Edition 1st Edition
Tools
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Toc

Table of Contents (19) Chapters Close

Hadoop Beginner's Guide
Credits
About the Author
About the Reviewers
www.PacktPub.com
Preface
1. What It's All About 2. Getting Hadoop Up and Running FREE CHAPTER 3. Understanding MapReduce 4. Developing MapReduce Programs 5. Advanced MapReduce Techniques 6. When Things Break 7. Keeping Things Running 8. A Relational View on Data with Hive 9. Working with Relational Databases 10. Data Collection with Flume 11. Where to Go Next Pop Quiz Answers Index

Time for action – importing data from a raw query


Let's see an example of an import where a raw SQL statement is used to select the data to be imported.

  1. Delete any existing output directory:

    $ hadoop fs –rmr employees
    
  2. Drop any existing Hive employee table:

    $ hive -e 'drop table employees'
    
  3. Import data using an explicit query:

    sqoop import --connect jdbc:mysql://10.0.0.100/hadooptest 
    --username hadoopuser -P
    --target-dir employees  
    --query 'select first_name, dept, salary, 
    timestamp(start_date) as start_date from employees where $CONDITIONS' 
    --hive-import --hive-table employees 
    --map-column-hive start_date=timestamp -m 1
    
  4. Examine the created table:

    $ hive -e "describe employees"
    

    You will receive the following response:

    OK
    first_name  string  
    dept  string  
    salary  int  
    start_date  timestamp  
    Time taken: 2.591 seconds
    
  5. Examine the data:

    $ hive -e "select * from employees"
    

    You will receive the following response:

    OK
    Alice  Engineering  50000  2009-03-12 00:00:00
    BobSales  35000  2011-10...
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