Re: Databases and Instances

On Tue, 04 Apr 2000 11:58:18 GMT, nsouto_at_nsw.bigpond.net.au.nospam (Nuno Souto) wrote:

>On Mon, 03 Apr 2000 23:31:57 GMT,
>granta_at_nospam.student.canberra.edu.au (Fuzzy) wrote:
>
>>- Complete independent set of data structures (i.e. tablespaces,
>>dbspaces) - not tied to any other part of the instance
>
>Yup, it has it. Since V3. 1982. Next?
>
>>- Independent system catalog
>
>Yes. Since V2, if memory doesn't fail me. In fact, it was to the best
>of my knowledge the first one to do it. Next?

You miss the point. I mean being able to have two objects with IDENTICAL fully qualified names in two separate areas ... including SCHEMA name! See below.

>>- Independent set of schemas
>
>You kidding? Since day one.

Nope, I can't have two schema's with identical names in one instance, because Oracle forces them into its one and only DB, and prevents it happening. With the other RDBMSs mentioned, identical schemas can be housed in different databases within the instance.

This is absolutely critical for proper application testing ... something often missed by the "Just use different schema" mantra of some Oracle afficianados.

>>- Independent configuration of performance and tuning params
>
>Yes. Start more than one instance with the same shared code. I
>believe exactly what happens to DB2 too. Not the slightest problem.

No, not quite. For example, each DB2 database can have independently configured things like buffer pools (analogous to shared pool in Oracle) that aren't tied to the instance config - each database has it's own (in fact, you can even tie them to individual tablespaces with the database!). You hit the nail on the head when saying Oracle needs separate instances for this.

>>Gee, let me see. Nope, Oracle flunks ALL OF THOSE!!!!!
>
>Nope. Go back to 101, buddy.

Bzzzt. Graduated long ago ... but there's a place there for you.

>Who said it doesn't?
>
>> (Not that I dislike Oracle, or am blind to DB2's problems, just
>>making my point).
>
>Yeah, but make sure the point is well made.
>
>>I'm not interested in what they used to do ... we're talking about
>>right now. The other DBs I mentioned have it, and Oracle doesn't.
>
>Only DB2 has it. And you know that full well. Not Sybase, not SQL
>Server. Not now.

And Informix (bet that puts a smile on your face.)

>Why change? It's there!

Not quite. You're right, there may be no need to change ... I was making the point that it would be bloody difficult for them to try it if they wanted to.

Ciao
Fuzzy
:-) Received on Wed Apr 05 2000 - 00:00:00 CDT