Re: Informix to Oracle question

I too converted from Informix several years ago ( just as Informix V7 came out ).

It seems that you may have the Informix terminology mixed up. You say "...have seperate instances of databases." Well, Informix architecuture is as follows:

Instance = collection of background processes that represent the RDBMS Database = named collection of schema objects ( tables, triggers, procedures, etc.. )
User = OS authenticated, used for permissions to access databases and the objects contained within a database.

Informix allows the creation of multiple databases ( as defined above ) within an Instance by using Create Database statement, then allows access via database permissions on OS level userids.

Oracle terminology/architecture is a bit different:

Instance= collection of background processes that represent the RDBMS

Database= usually spoken in reference to the entire Instance. That is, a database and an Instance of the RDBMS can be "seen" as the same thing in Oracle.

User = a userid defined within the database/instance. Each user is analogous to the "Database" in Informix speak. That is, each User in an Oracle database is the same thing as a Database in Informix.

So, for example, if you have an Instance of Informix, say ONCONFIG=instance1, and within the instance you have three databases defined as db1, db2, and db3, a comparable Oracle configuration would look like this:

SID=inst1

Within the inst1 instance, you'd define three users ( or Schema's ) using the Create User SQL syntax ( db1, db2 and db3 ). Each of the new schemas would contain their own set of objects, which could ( for best results ) be placed in their own separate tablespaces on different disks/directories ( as you stated ).

As for recovery, Oracle and Informix vary drastically here, so you'd be better off just diving into the backup/recovery documents.

Hope this helps...

-Kevin

"VWP914" <vwp914_at_aol.com> wrote in message news:20001117013307.15477.00000166_at_ng-bh1.aol.com...
> Hi everybody:
>
> I come from an Informix background where we log into a particular database
> instance by going to the directory, and typing 'isql' to get in. In
 Oracle, it
> seems that all the tables are kept in one central location and only
 seperated
> by users. This leads me to wonder what happens when you run out of space
 on
> that partition. Is there not a way to have seperate instances of
 databases?
> For example, can a marketing database be kept in a different directory
 from an
> accounting database, etc?
>
> My other question concerns backup. In Informix, when someone screws up a
 table
> really bad, we just restore the files that make up that table. Does the
 same
> hold for Oracle?
>
> Any help would be much appreciated.
Received on Fri Nov 17 2000 - 12:58:22 CST