Re: One vs many databases

"Karsten Farrell" <kfarrell_at_belgariad.com> wrote in message news:trjR9.1308$Iy4.104463592_at_newssvr17.news.prodigy.com...
> John Hunter wrote:
> > Hi Gang,
> >
> > I'm looking at submitting a business case to management that will
justify
> > changing from our current structure of many oracle databases to one big
> > database. We currently run many separate databases (financial, sales,
> > purchases etc...) all based on functional areas. These are all inhouse
> > written systems. My problem with having all these instances is with
trying
> > to link data together. We need to have realtime data shared amonst the
> > systems. Dblinks are quite slow and although materialized views have
lots
> > to offer they consume a fair amount of overhead.
> >
> > Anyway, I've done some web searches looking for the pros and cons of
many
> > instances vs. one instance and have yet to find a good whitepaper on
this
> > subject. I did read through the long (70 or so posts) when someone said
they
> > were going to install 50 instances on one host, but it didn't really
answer
> > the question.
> >
> > Thanks,
> > -John
>
> IMHO there isn't one - and only one - clear answer to this question.
> There are a lot of pros and cons - not all of which are technical. Some
> are simply the way things are in the company and no one is going to set
> aside a pot of money to fix. I don't think other shops have our
> requirements ... so what I say is very site-specific ... YMMV.
>
> For example, we keep our data warehouse in a separate database because
> it has vastly different resource requirements (in SGA size, batch
> reports, inelegant user-defined ad-hoc queries, etc). We also have a
> bunch of formerly unused NT workstations that were sitting around with
> nothing to do, but that do quite nicely with "departmental" databases
> (that is, databases that don't need a lot of data from other databases).
> Management didn't want to see them idle. We also have some databases
> that don't need to be backed up ... and ones that we'd have our fingers
> chopped off if we didn't. Setting up RMAN scripts to back up only the
> pieces we want of a single, large db might be more difficult than
> setting up RMAN scripts only for a few small, whole databases.
>
> If you have an unlimited budget in your company, then go for the big RAC
> database on a SAN. Kinda reminds me of all the arguments 30 years ago
> when we were considering switching from the big iron mainframes to DEC
> VAXen minicomputers. It was almost a religious war between the folks on
> the single or multiple side of the fence. Now, our Sun box with a couple
> dozen CPUs can really handle the database we did decide to make "big."
>

IMHO there is one - and only one - clear answer to this question. It depends.

(Sorry, couldn't resist) :-)

Regards,
Paul Received on Fri Jan 03 2003 - 14:16:16 CST