Choosing a data storage engine is an important decision, but it doesn’t have to be painful if you know the landscape. We’ll look at several DBMSs (and a few you’ve never heard of), compare and contrast them based on use-cases, and how to plug each into Ruby. Authoring the book "Seven Databases in Seven Weeks" has opened up a whole world of database alternatives that I never before seriously considered. It’s an important decision to be made by research, not buzzwords – and we’ve sifted through them so you don’t have to. At the very least we can settle the Mongo v. Couch debate (hint: they’re both awesome). This is not the same RailsConf talk. This is split into two parts: The components of modern databases: A 30,000 foot view of the current database ecosystem Understanding why the CAP theorem is true Understanding map/reduce from the Ruby perspective 12 databases in 12 minutes: The similarities/differences of the most popular open source DBs today When to use them, when to avoid them Which Ruby drivers to use