Update: Review of Hadoop the Definitive Guide 3nd Edition
I spent some time reading 2 Hadoop books: Hadoop the Definitive Guide 2nd Edition by Tom White and Hadoop In Action by Chuck Lam. Both books were well written but seemed to be aimed at a different audience.
Hadoop the Definitive Guide 2nd Edition seems to be aimed more at the programmer. There are lots of code samples and the author goes through the code line by line and does a great job of explaining why each one is important. I liked this book’s code examples better than Hadoop In Action because the book’s examples seemed to more real world and applicable. He goes into better detail about the programming side of things like debugging and logging. If you know enough about MapReduce to be dangerous, but want to know about Hadoop’s implementation of it, head to chapter 6 “How MapReduce Works”. I am a visual person and enjoyed this book’s diagrams for understanding the flow. Hadoop In Action doesn’t have any diagrams. This book contains more overview chapters of the Hadoop associated projects like Pig and HBase.
Hadoop In Action seems to be aimed more at people wanting to learn about Hadoop. It isn’t a cursory look at Hadoop, but this would be the book I would recommend to a manager or non-programmer to learn about Hadoop. For managers, I would send them straight to chapter 7 “Cookbook” which shows how other companies have used this technology. It also gives a better overview of maintaining and setting up a Hadoop cluster.
If you starting from scratch on Hadoop, I recommend you start out with Hadoop In Action. If you are going straight to coding or already have a handle on MapReduce, then I recommend you buy Hadoop the Definitive Guide 2nd Edition.