Performance differences between '.find' and '.where' methods

Question

I am using Ruby on Rails 3.0.7 and I would like to know, regarding performance matters, what are differences between the User.find(<id>) method and the User.where(:id => <id>) method.

Answer 1

Under the hood, find does more or less what you're describing with your where. You can find the details in this post. That being said, if you're looking to grab a single record by id, then you might want to use find_one. That's what find winds up doing when you call it with a single argument of an id, but you'll skip past all the other code it needs to run to figure out that's what you wanted.