Re: Database-valued attributes?

"Bob Badour" <bbadour_at_golden.net> wrote in message news:NqydnbqEFO6qei-iRVn-tw_at_golden.net...
> "Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message
> news:botpmf$ooe$1_at_gazette.almaden.ibm.com...
> > "Bob Badour" <bbadour_at_golden.net> wrote in message
> > news:GLadnaU5LYVh0i-iRVn-tg_at_golden.net...
> > > "Paul Vernon" <paul.vernon_at_ukk.ibmm.comm> wrote in message
> > > news:bot3ev$oqa$1_at_gazette.almaden.ibm.com...
> > > > "Bob Badour" <bbadour_at_golden.net> wrote in message
> > > > news:EZKdnUmgA62gjiyiRVn-tw_at_golden.net...
> > > > > > poss rep with more than 1 component a tuple of those components,
> or
> > a
> > > > > list, a set, an array or just 'a thing with components'?
> > > > >
> > > > > It is a possible representation. The remainder is internal.
> > > >
> > > > Thanks.
> > > >
> > > > Can't say I'm happy with such dereliction of definition though. I'd
> like
> > > to
> > > > see the logical model cover such matters rather than leaving it to
be
> an
> > > > 'internal' matter. Oh well.
> > >
> > > Physical independence is not a dereliction.
> >
> > One of us in the group said
> >
> > "I doubt Dijkstra would consider a division between applications and
data
> > management appropriate. I know he expressed skepticism regarding the
> > division into conceptual, logical and physical."
> >
> > Has anyone got the quote? I think I share some of his skepticism...

>

Maybe the above was inspired by his comments in 1976 on "Database Technology" in this trip report

http://www.cs.utexas.edu/users/EWD/ewd05xx/EWD577.PDF

His list of "crazy expressions" does include   "logical abstractions"
  "mapping of one level of abstraction into the layer below" etc

So I guess one could read that as skepticism regarding the division into conceptual, logical and physical.

However I think I saw another quote somewhere in which he questioned the idea that the 'physical' was not also 'logical'. I.e is 'physical' therefore 'illogical' ?

At the least, I'm not a big fan of the terminology we use. What does the word logical, in the context of "logical model" really mean?

Regards
Paul Vernon
Business Intelligence, IBM Global Services Received on Thu Nov 13 2003 - 13:06:07 CET