I need to iterate over a big set of data, and I want to do it without sucking the whole thing into memory. Unfortunately, as far as I can tell ActiveRecord does just that, which is a pity because it could probably be made to do something like this

Foo.find_and_loop(:all, :conditions => '....') do |res|
  do_something(res.foo, res.bar)
end

without too much trouble. You’d have to have some fancy interaction between AR and the connection adapters so as to run your loop at a low level, but it should be possible. All the databases that I looked at let you operate that way in their C API’s.

Doubtless, this is something “opinionated”, and of use to a small percentage of rails users, so it’s probably not worth submitting a bug report, but it’s a minor annoyance all the same.