Sign In Start Free Trial
Account

Add to playlist

Create a Playlist

Modal Close icon
You need to login to use this feature.
  • Book Overview & Buying Mastering Hadoop
  • Table Of Contents Toc
Mastering Hadoop

Mastering Hadoop

By : Karanth
4 (3)
close
close
Mastering Hadoop

Mastering Hadoop

4 (3)
By: Karanth

Overview of this book

Do you want to broaden your Hadoop skill set and take your knowledge to the next level? Do you wish to enhance your knowledge of Hadoop to solve challenging data processing problems? Are your Hadoop jobs, Pig scripts, or Hive queries not working as fast as you intend? Are you looking to understand the benefits of upgrading Hadoop? If the answer is yes to any of these, this book is for you. It assumes novice-level familiarity with Hadoop.
Table of Contents (15 chapters)
close
close
14
Index

MapReduce input

The Map step of a MapReduce job hinges on the nature of the input provided to the job. The Map step provides maximum parallelism gains, and crafting this step smartly is important for job speedup. Data is split into chunks, and Map tasks operate on each of these chunks of data. Each chunk is called InputSplit. A Map task is asked to operate on each InputSplit class. There are two other classes, InputFormat and RecordReader, which are significant in handling inputs to Hadoop jobs.

The InputFormat class

The input data specification for a MapReduce Hadoop job is given via the InputFormat hierarchy of classes. The InputFormat class family has the following main functions:

  • Validating the input data. For example, checking for the presence of the file in the given path.
  • Splitting the input data into logical chunks (InputSplit) and assigning each of the splits to a Map task.
  • Instantiating a RecordReader object that can work on each InputSplit class and producing records to the Map task...
CONTINUE READING
83
Tech Concepts
36
Programming languages
73
Tech Tools
Icon Unlimited access to the largest independent learning library in tech of over 8,000 expert-authored tech books and videos.
Icon Innovative learning tools, including AI book assistants, code context explainers, and text-to-speech.
Icon 50+ new titles added per month and exclusive early access to books as they are being written.
Mastering Hadoop
notes
bookmark Notes and Bookmarks search Search in title playlist Add to playlist font-size Font size

Change the font size

margin-width Margin width

Change margin width

day-mode Day/Sepia/Night Modes

Change background colour

Close icon Search
Country selected

Close icon Your notes and bookmarks

Confirmation

Modal Close icon
claim successful

Buy this book with your credits?

Modal Close icon
Are you sure you want to buy this book with one of your credits?
Close
YES, BUY

Submit Your Feedback

Modal Close icon
Modal Close icon
Modal Close icon