Stephen Frost <sfrost@snowman.net> writes:
> * David G. Johnston (david.g.johnston@gmail.com) wrote:
>> Not sure if this is what you mean but there is no concept of "negative
>> state" in the permissions system. Everything starts out with no
>> permissions. Grant adds permissions and revoke un-adds granted
>> permissions. Revoking something that doesn't exist is either a no-op or a
>> warning depending on the context - either way its doesn't setup a
>> "forbidden" state for the permission.
> This isn't entirely correct. Functions are the classic example where
> EXECUTE to PUBLIC is part of the default and the "negative" state of
> having a function where EXECUTE is REVOKE'd from PUBLIC is entirely
> reasonable and even common.
FWIW, I thought David's description was fine. The fact that the initial
state of an object typically includes some positive grants doesn't change
the fact that there's no such thing as a negative grant. In particular,
if there is a GRANT TO PUBLIC, no amount of revoking that privilege from
individual users will have any effect, because the public grant is still
there.
regards, tom lane