Foreword
In the last 10 years, the Internet has challenged relational databases in ways nobody could have foreseen. Having used MySQL at large and growing Internet companies during this time, I’ve seen this happen firsthand. First you have a single server with a small data set. Then you find yourself setting up replication so you can scale out reads and deal with potential failures. And, before too long, you’ve added a caching layer, tuned all the queries, and thrown even more hardware at the problem.
Eventually you arrive at the point when you need to shard the data across multiple clusters and rebuild a ton of application logic to deal with it. And soon after that you realize that you’re locked into the schema you modeled so many months before.
Why? Because there’s so much data in your clusters now that altering the schema will take a long time and involve a lot of precious DBA time. It’s easier just to work around it in code. This can keep a small team of developers busy for many months. In the end, you’ll always find yourself wondering if there’s a better way—or why more of these features are not built into the core database server.
Keeping with tradition, the Open Source community has created a plethora of “better ways” in response to the ballooning data needs of modern web applications. They span the spectrum from simple in-memory key/value stores to complicated SQL-speaking MySQL/InnoDB derivatives. But the sheer number of choices has made finding the right solution more difficult. I’ve looked at many of them.
I was drawn to MongoDB by its pragmatic approach. MongoDB doesn’t try to be everything to everyone. Instead it strikes the right balance between features and complexity, with a clear bias toward making previously difficult tasks far easier. In other words, it has the features that really matter to the vast majority of today’s web applications: indexes, replication, sharding, a rich query syntax, and a very flexible data model. All of this comes without sacrificing speed.
Like MongoDB itself, this book is very straightforward and approachable. New MongoDB users can start with Chapter 1 and be up and running in no time. Experienced users will appreciate this book’s breadth and authority. It’s a solid reference for advanced administrative topics such as replication, backups, and sharding, as well as popular client APIs.
Having recently started to use MongoDB in my day job, I have no doubt that this book will be at my side for the entire journey—from the first install to production deployment of a sharded and replicated cluster. It’s an essential reference to anyone seriously looking at using MongoDB.
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