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Re: Normalization by Composing, not just Decomposing

From: Alan <alan_at_erols.com>
Date: Mon, 12 Apr 2004 15:43:58 -0400
Message-ID: <c5erh9$qt9b$1@ID-114862.news.uni-berlin.de>


Normalization rules are Codd's rules, not God's rules. They are a _guide_ to distributing data among entities, not a dogmatic recipe. You seem to want to project a certain amount of dogmatism on everything, as if life were black and white. It isn't, it's an infinite number of shades of gray (well 16,384 at least).

Did you hear about the programmer they found dead in the shower? He was stiff, grasping a bottle of shampoo, his eyes apparently fixed on the instructions, "Lather, rinse repeat."

Here's the general rule of thumb: Normalize to 3NF, and then see if that works for you in your situation. If it doesn't, then denormalize or normalize further. Iterate.

You ask, "Are you adhering to relational theory when deploying an OLAP database where
the data is in fact & dimension tables?" Did you read my message? What did I write about normalization and the star schema?

Data is not _modeled_ as "OLAP cubes". Cubes are an implementation, modelling is analysis and maybe design.

"Dawn M. Wolthuis" <dwolt_at_tincat-group.com> wrote in message news:c5ecb7$e2f$1_at_news.netins.net...
> "Alan" <alan_at_erols.com> wrote in message
> news:c5e6m0$lo87$1_at_ID-114862.news.uni-berlin.de...
> > Realtional theory as a data theory is analagous to democracy as a form
of
> > government- it may not be perfect, but so far, there's nothing better in
> > most cases.
>
> Have you concluded this by reviewing some emperical data that has been
> collected or because you adhere to some philosophy or what? Could I state
> something contradictory with as much logical backing?
>
> > Denormalization in itself has nothing directly to do with OLAP, except
> that
> > one may denormalize more for an OLAP application than an OLTP
application.
> > However, in OLAP, you are not necessarily denormalizing so much as
> > "re-normalizing", in that you are really developing a diiferent
> distribution
> > among entities for the same data, such as in a star schema. It's not
> > normalized, but it's not denormalized either. It's just different. I
> suppose
> > an argument could be made that (in the case of a star schema), you start
> > with a normalized schema, and then apply transformation rules (no, don't
> ask
> > me what they are- there are books on the topic) to transform it into a
> star
> > schema. Think about it- a basic star schema is essentially a giant
> > many-to-many linking table (the fact table) with a bunch of descriptive
> data
> > tables (dimensions).
>
> Are you adhering to relational theory when deploying an OLAP database
where
> the data is in fact & dimension tables? I have not seen a star schema for
> the purposes of OLAP without some rules broken such as duplication of
data.
> But I'm fine with it either way -- just curious whether most relational
> theorists would view data modeled as OLAP cubes as following "the
> ules". --dawn
> <snip>
>
>
Received on Mon Apr 12 2004 - 14:43:58 CDT

Original text of this message

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