Re: Oracle 7 Data File Storage - Newbie Question

In article <1998072413440576740_at_zetnet.co.uk>,   Bernadette Pinto <b.pinto_at_zetnet.co.uk> wrote:
> In a multi-user environment where, say, three users are accessing the
> same database tables, where is the data file(s) on which the data is stored?

Well, if the setup is C/S (client-server) the database file *.dbf are stored on the database server or on an array of disks (RAID) controlled by that server.

But there can be more than one instance of a database on any given server and each instance can contain more than one application. Each application in turn should then have separate datafiles. Ideally, index files should be physically separate from data files, i.e. on a separate disk/disk-controller for performance reason. (I'm simplifying here)
>
> Also, if each user asks for the rowid of a row from one specific
> table, will each user get the same rowid returned? (I mean, will the
> rowid for the user's database instance or the server's database be returned).
>

The rowid will be the same as it actually expresses the physical location of the data in the *.dbf file(s).

> The two questions above lead me to asking this third question:
>
> How is an Oracle database stored? I have assumed that in a multi-user
> environment the database was stored on the server. I also assumed
> that each client PC had an 'instance' of the database (I.e., a
> snapshot of the server's database stored locally). If this is so, is
> it possible to return information regarding the physical location of
> the local database instance (can't think why you would want to, but
> am curious).
>

Normally, there is no local representation of the database a client PC is accessing, only of the actual selected data (either in memory or on the local PCs disk)
only of the

> Thanks for taking the time to answer these questions.
>
> Best wishes
>
> Bernadette
>
>

The issues involved are far more complex than this but as a starter...

HTH --
Oliver Willandsen
European Commission
http://europa.eu.int
All remarks are my own and do not necessarily reflect official European Commission policy

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