Re: What does this NULL mean?

From: David Cressey <dcressey_at_verizon.net>
Date: Wed, 14 Dec 2005 15:36:02 GMT
Message-ID: <CZWnf.3151$Bj4.3108@trndny01>

"JOG" <jog_at_cs.nott.ac.uk> wrote in message news:1134572707.151136.207630_at_f14g2000cwb.googlegroups.com...
> mountain man wrote:
> > "David Cressey" <dcressey_at_verizon.net> wrote in message
> > news:K2Qnf.2517$0z.2002_at_trndny02...
> > >
> > > "mountain man" <hobbit_at_southern_seaweed.com.op> wrote in message
> > > news:ttrnf.19034$ea6.17392_at_news-server.bigpond.net.au...
> > >
> > >> Dependent upon the measure of complexity of your database
> > >> it may be argued that the design is never complete because it
> > >> is under constant evolution.
> > >
> > > [snip]
> > >
> > > Your post is outstanding, perhaps the best I've read in this thread.
> > >
> > > I think "change management in databases" deserves a discussion of its
own.
> >
> >
> > There has been limited discussion here, and there are articles
> > about on this issue under the keyphrase of "schema evolution".
> >
> > The issue is avoided by Date et al (AFAIK) whereas it is
> > precisely this issue of schema change that should be subject
> > to the principles espoused by the relational model.
> >
> > The RM guides the design of new databases, and it obviously
> > also must guide the evolution of old databases, but this aspect
> > has not yet been thrashed out in any formalised manner.

>

> These sort of considerations are the exact reason that boundaries are
> being pushed in areas like bioinformatics, where knowledge and
> understanding of the worldview being modelled is constantly improving
> and shifting - this leads to the schema they work with being in a state
> of constant flux. All too often developments appear to be performed in
> an ad hoc manner, but I predict that eventually, it will be from these
> sort of areas that advancements will emerge (with hopefully a
> theoretically sound as opposed to purely pragmatic solutions). Now this
> flux happens in the business world too, but to a lesser extent where it
> is all too easy to try and paper over the cracks, and I just don't see
> the impetus for advances stemming from there.
>
It seems to me that theory tends to come along behind, and clean up the mess that the pioneers were too hurried to clean up. Business aims at success, perhaps based on novelty. Once a success has been acheived, business aims at repeatability. The impetus for advances usually stalls there.

It seems to me that there is room for all three: ground-breaking innovation, theoretical soundness, and busiinesslike reliability. And I don't think they should be forced to be on lock step with each other. Received on Wed Dec 14 2005 - 09:36:02 CST