I think you'd want to index by subreddit as well in the case of Reddit. Getting 500 upvotes on /r/pics is probably not the same as 500 upvotes on some relativel

I think you'd want to index by subreddit as well in the case of Reddit. Getting 500 upvotes on /r/pics is probably not the same as 500 upvotes on some relatively obscure subreddit.