title: Should I use Postgres's roles system for a web app's user management?
body: <p>Postgres already has fully featured user management system. Why should I duplicate this functionality and use another one on top of that? And I think this is the right place to manage users &amp; groups as it allows fine-grained control. Am I wrong? Is there some php libraries that already have done that?<br>
  I should add that the app in question is not a public web-site, but a corporate app working in the private network.</p>