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Re: What is a Catalog and Database according to Oracle?

From: fumi <fumi_at_tpts5.seed.net.tw>
Date: 25 Sep 1999 16:54:19 GMT
Message-ID: <7siunr$ltp$1@news.seed.net.tw>

Steven Hill <java410_at_yahoo.com> wrote in message news:37E68E3E.4FFEBBC9_at_yahoo.com...
> I'm trying to reconcile some Oracle terms with some ANSI SQL & JDBC
> terminology and I'd like to know if I've made any mistakes. In other
> word, which of the following statements are false and why?
>
> 1) An "Oracle database" is an instance of an Oracle DBMS, thus if there
> is more than one instance running on a computer then the computer has
> more than one database running?

No.
A database physically consists of some files. A instance consists of memory buffers and some background processes. One or more instances on a computer can open the same one database, though no one will construct such configuration.

> 2) Do Oracle DBAs use the terms "Oracle database" and "Oracle server"
> interchangably? Or does "server" mean one computer with possibly
> multiple databases running on it.

No.
They are not the same.
Oracle server consists of an Oracle database and Oracle instance.

> 3) Is an "Oracle user" the same as the ANSI SQL term "catalog"? If so,
> then a Oracle user can have only one catalog? Do Oracle DBA's call a
> catalog the "user's database"?

No.
Oracle use the term "data dictionary" for catalog.

> 4) The Oracle docs say that a user account can only own a single schema
> which has the same name as the user name.
> Therefore, a user's catalog or user's database (identified by the user's
> name) contains one schema owned by the user (also identified by the
> user's name) and portions of other users' catalogs/schemas which the
> user has access to?

No.
Oracle doesn't use such a term like "user's catalog" or "user's database". The objects a user can access is based on the user's privileges.

> 5) An Oracle DBA can setup up additional user accounts, say 5, for the
> same user ie, JSmith1, JSmith2... JSmith5. with different schema access
> privileges; thus, simulating one ANSI SQL "cluster", defined as a
> "group of catalogs" and not to be confused with Oracle cluster meaning?

Although he can, he doesn't do.
Since it is meaningless and sounds borrow trouble.

> 6) The scope of an "Oracle user" OWNERSHIP is limited to one database
> -- the one it is defined on?

Yes.

> 7) The scope of an "Oracle user" ACCESS can span multiple databases
> using dblinks? Therefore, a user's catalog can span multiple databases?

No.
The schema is defined in only one database. A user can access more than one user's objects in another database using different database links to the same remote database.

> 8) "Oracle dblinks" allow remote objects in a different "Oracle
> database" to be seemlessly included in a user's catalog? So, for
> example, issuing one Oracle request for a list of all tables that a user
> has access to will include any remote tables distinguished by datalink @
> tablename syntax. ?

No.
The objects in remote database are considered as another one's objects, although the schema names may be the same.

> 9) Or is the same request also needed on remote database inorder to
> discover the remote tables? If this true, how does the client app know
> what datalink to use if it is not hard-coded in the app?

??? waht request?
You need an account to logon the remote database. The database links you can defined are based on your accounts on remote databases. Received on Sat Sep 25 1999 - 11:54:19 CDT

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