Re: Ynt: Creation of Oracle databases

"TurkBear" <noone_at_nowhere.com> wrote in message news:0uqejtgvbnf5k9gl0aasr9c2sgdsqbc6i3_at_4ax.com...
>
> There appears to be some confusion about terms here;
> An Oracle instance is what many other databases call a database ( esp
 sqlServer
> and Access) It can, and usually does, have many schemas - that is, a set
 of
> objects ( tables,views,procs,etc) 'owned' by a particular Oracle account..

There is indeed a confusion of terms ...in your own posting, unfortunately. An Oracle Instance does not have schemas. Neither does it have objects. An Instance consists of the System Global Area (itself comprised of the Shared Pool, Log Buffer and Data Buffer Cache) and the background processes (such as LGWR, DBWR, CKPT, SMON and PMON). An Instance is therfore just an area of memory on a server, with a bunch of processes (or threads, if you've got NT) modifying those memory addresses as Users do things with SQL.

A schema and its objects reside in the Database, which is nothing more than less than a collection of physical files on disk. In particular, there must be a minimum of four files on disk: one control file, one data file and two online redo logs.

The contents of those files are managed (ie read from and written to) by the Instance. One Instance (as you go on to say) can only ever manage one Database (and that's true in Parallel Server, too).

I think I understand what you are trying to say above -because I'd be tempted to map the SQL Server 'database' to an Oracle schema, too (though tablespace comes a close second). It's just that rather loose of the word 'Instance' in your second sentence that worries me!

Regards
HJR
>
> All schemas use the 'common' resources of the instance..
>
> In short, the concept of 'multiple databases in a single instance' is
 incorrect
> when used in the Oracle context;
>
> Try http://technet.oracle.com and check out the Server Concepts docs for
 a
> better explanation of the Oracle structure and design..
>
>
> schwickert_at_yahoo.com (T. Schwickert) wrote:
>
> >Hi,
> >
> >no, I think not. It's possible to share ONE database in more
> >instances (parallel Server), but in ONE instance there
> >can only one database at a time.
> >Nevertheless, one instance could handle more databases, but not at
> >the same time.
> >
> >Hope I say some right :-)
> > Thomas
> >
> >"Murat YILDIZ" <myildiz_at_bellona.com.tr> wrote in message
> >> Apart from this thread, isn't it possible to create more than one
 database
> >> within an instance?So that multiple databases uses the same Database
> >> resources?
> >>
> >> Murat
> >>
>
>
>
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Received on Mon Jun 25 2001 - 15:34:17 CDT