Mark D Powell wrote:
> Daniel Morgan <damorgan_at_x.washington.edu> wrote in message news:<1089944500.886043_at_yasure>...
>
>>Praveen wrote:
>>
>>
>>>Hi..All,
>>>
>>> I have a quick question. Why am I not able to see the user "PUBLIC"
>>>in ALL_USERS table.
>>>
>>>Regards,
>>>
>>>P
>>>
>>
>>Because public is not a user it is a role.
>>
>>Daniel Morgan
>
>
> I recently read a series of emails on the nature of PUBLIC. While
> Oracle may encode the base table entry with the role flag technically
> the definition of a role (from the 9.2 Master Glossary) is "A named
> group of related privileges. You can grant a role to users or other
> roles."
>
> Roles are collections of privileges and do not own objects. A schema
> on the other hand does own objects and can receive grants.
> "Collection of database objects, including logical structures such as
> tables, views, sequences, stored procedures, synonyms, indexes,
> clusters, and database links. A schema has the name of the user who
> controls it."
>
> According to the authors of this series (Oracle employees) PUBLIC is a
> schema, plan and simple.
>
> I think based on the internal coding PUBLIC is really a hybrid: it is
> a an object owning user, schema, that has been encoded as a role to
> allow granting of reference to PUBLIC's objects but still not grant
> automatic privilege to the referenced objects. Most of PUBLIC's
> objects are public synonyms which in turn refer to objects owned by
> other users. All users gain access to the reference but not to the
> underlying object without additional privileges. PUBLIC may or may
> not supply those additional privileges which is where the role
> attribute comes into play.
>
> PUBLIC is a pretty neat trick and is probably a good topic for a class
> room debate.
>
> HTH -- Mark D Powell --
Thanks to this thread and your suggestion it is now part of a classroom
discussion ... It will only turn into a debate if a student wishes to
make it so.
Thanks Mark.
Daniel Morgan
Received on Fri Jul 16 2004 - 18:26:28 CDT
