Learning Hadoop 2

Chapter 1. Introduction

This book will teach you how to build amazing systems using the latest release of Hadoop. Before you change the world though, we need to do some groundwork, which is where this chapter comes in.

In this introductory chapter, we will cover the following topics:

• A brief refresher on the background to Hadoop
• A walk-through of Hadoop's evolution
• The key elements in Hadoop 2
• The Hadoop distributions we'll use in this book
• The dataset we'll use for examples

A note on versioning

In Hadoop 1, the version history was somewhat convoluted with multiple forked branches in the 0.2x range, leading to odd situations, where a 1.x version could, in some situations, have fewer features than a 0.23 release. In the version 2 codebase, this is fortunately ...