[joevandyk]

Lazy loading in ActiveRecord works like:

users = User.where(:age => 10) # no rows fetched

# Once you access something on users, then the query happens users.each do |user| # something end

It's not really that "magic", it's useful.

ActiveRecord uses joins (mostly). If you are using a "non-standard" table schema, you can tell ActiveRecord what column to use on joins.