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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 FREE CHAPTER 2. Getting Hadoop Up and Running 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 – redefining the table with the correct column separator


Let's fix our table specification as follows:

  1. Create the following file as commands.hql:

    DROP TABLE ufodata ;
    CREATE TABLE ufodata(sighted string, reported string, sighting_location string,
    shape string, duration string, description string)
    ROW FORMAT DELIMITED
    FIELDS TERMINATED BY '\t' ;
    LOAD DATA INPATH '/tmp/ufo.tsv' OVERWRITE INTO TABLE ufodata ;
  2. Copy the data file onto HDFS:

    $ hadoop fs -put ufo.tsv /tmp/ufo.tsv
    
  3. Execute the HiveQL script:

    $ hive -f commands.hql 
    

    You will receive the following response:

    OK
    Time taken: 5.821 seconds
    OK
    Time taken: 0.248 seconds
    Loading data to table default.ufodata
    Deleted hdfs://head:9000/user/hive/warehouse/ufodata
    OK
    Time taken: 0.285 seconds
    
  4. Validate the number of rows in the table:

    $ hive -e "select count(*) from ufodata;"
    

    You will receive the following response:

    OK
    61393
    Time taken: 28.077 seconds
    
  5. Validate the contents of the reported column:

    $ hive -e "select reported from ufodata...
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