Label Security and Fine-grained auditing

I once discussed with you all regarding Oracle's FlashBack Query feature to recover a database to a certain point of
time.That time you all suggested some indepth cons of this and how it is resource hungry.<br /><br />One more feature
thatI am not sure PostgreSQL has is, row-level, column-level security. Oracle call this Label-Security in which you
definea policy for certain columns so that they are not visible to un-authorised users during SELECT queries. This is
animportant security enhancement. One other feature is called Fine-Grained Auditing. Ability to track user activities.
Ihope this is in PostgreSQL in one form or the other. <br /><br />I want to know your views on this.<br />