I haven't had a lot of experience with caching, and I agree with your comment above about database views, but wouldn't the complications be mitigated by using the approach DHH detailed recently? http://37signals.com/svn/posts/3113-how-key-based-cache-expi...

That is, incorporating `updated_at` into the cache key, and using `touch: true` on your AR relations to make sure that caches of affected parent objects get expired too?

Are there other complications I may not have run into yet?