unique id in a find

I'm trying to do something that seems easy but I can't figure it out. I have Post.find(:all, :order => "created_at desc", :limit => 10) but if a user has a bunch of posts, I only want one of them to show up in the results so I have 10 posts with 10 unique user_ids. I feel like distinct comes into play here somewhere.

Anyone have any thoughts on this?



You can use distinct as you mentioned or 'group by' works too.