What we did and didn't cover in this book
With our focus on beginners, the aim of this book was to give you a strong grounding in the core Hadoop concepts and tools. In addition, we provided experiences with some other tools that help you integrate the technology into your infrastructure.
Though Hadoop started as the single core product, it's fair to say that the ecosystem surrounding Hadoop has exploded in recent years. There are alternative distributions of the technology, some providing commercial custom extensions. There are a plethora of related projects and tools that build upon Hadoop and provide specific functionality or alternative approaches to existing ideas. It's a really exciting time to get involved with Hadoop; let's take a quick tour of what is out there.
Note
Note, of course, that any overview of the ecosystem is both skewed by the author's interests and preferences and outdated the moment it is written. In other words, don't for a moment think this is all that's available...