title: How do large sites accomplish row-level permissions?
body: <p>So I am making a small site using cakephp, and my ACL is set up so that every time a piece of content is created, an ACL rule is created to link the owner of the piece of content to the actual content.  This allows each owner to edit/delete their own content.  This method just seems so inefficient, because there is an equivalent amount of ACL rules as content in the database.  I was curious, how do big sites, with millions of pieces of content, solve this problem?</p>