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Re: Users vs. Schemas

From: Brian Peasland <>
Date: Wed, 27 Jun 2007 15:33:02 -0500
Message-ID: <4682bd4d$0$16272$>

Matthias Hoys wrote:

> "Mark D Powell" <> wrote in message 
>> On Jun 27, 11:14 am, HansF <> wrote:

>>> On Jun 27, 7:58 am, wrote:
>>>> I'm an oracle novice and I'm a little confused by Users vs. Schemas.
>>>> I had thought that User == Schema.
>>>> However, while using the schema browser feature in TOAD GUI I noticed
>>>> that under the 'Schemas' node there is an entry for 'PUBLIC' for which
>>>> there is no corresponding entry under the 'Users' node.
>>>> Every other Schema/User has an entry in both.
>>>> Why is PUBLIC different?
>>>> Dose User == Schema OR does User != Schema?
>>> Yes, there is a lot of confusion around this.
>>> I look at it this way:
>>> - A schema is a namespace for the definitions of objects.
>>> - A user is an identifier to which resources may be granted.
>>> One resource that may be attached to an Oracle User is the schema
>>> namespace. In which case the schema namespace and the Oracle Userid
>>> have the same identifier.
>>> Since it is so commonly required (and partly due to history), when an
>>> Oracle User is created the associated schema namespace is always
>>> created.
>>> However, as you have seen, the schema does not necessarily imply
>>> user.
>>> If you take this one large step further, you will find that PUBLIC is
>>> a special case ... it is neither a USER nor a ROLE, but rather a
>>> [url=]'USER
>>> GROUP'[/url].
>>> /Hans
>>> --
>>> Hans Forbrich (mailto:
>>> *** Feel free to correct me when I'm wrong!
>>> *** Top posting [replies] guarantees I won't respond.
>> Pete makes an interesting argument but Oracle has published a paper in
>> May of 2007 which may also be of interest to those with access to
>> metalink:
>> PUBLIC : Is it a User, a Role, a User Group, a Privilege ?
>> Document  234551.1
>> The ID is created with the command: "create role public".
>> My argument was that is is a schema.
>> HTH -- Mark D Powell --
>  I think of a schema as every user who owns objects, so you can have users 
> with no corresponding schema. But PUBLIC is the exception on the rule :-)

I always thought of the schema as the collections of objects owned by a particular user. And some users have no objects.



Brian Peasland

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