How to build a search engine with Ruby on Rails: Introducing the Whereable design pattern

You don’t hear this one every day: I just made a critical database query 10x faster by moving the bulk of the complexity out of SQL and back into Ruby. This post will explain how I did it, plus how you can apply a similar approach to rethinking search in your own application. (In a hurry? Jump straight to the codey bits.)I maintain an app for studying Japanese called KameSame that’s built with Rails and Postgres (I talked about it in The Selfish Programmer). Last weekend I rewrote its Japanese-English dictionary search feature for at least the third time and I finally managed to strike the right balance between flexibility and speed.