"Jaro" <jaro80(at)gmail(dot)com> writes:
> I'd like create several users and several databases, ever user should
> be root only for own database
Anyone who is superuser in any database can certainly override any
restrictions you might think to put on him. (Hint: he can get at
the filesystem.)
If you really wish to hand out superuser to people you don't entirely
trust, then give each of them their own installation ($PGDATA tree),
running under a Unix account that isn't shared with anything else.
regards, tom lane