Re: Lucid statement of the MV vs RM position?
Date: 1 May 2006 17:21:44 -0700
Message-ID: <1146529303.993150.151540_at_y43g2000cwc.googlegroups.com>
JOG wrote:
> dawn wrote:
> > Jan Hidders wrote:
> > > dawn wrote:
> > > > Jan Hidders wrote:
> > > > > dawn wrote:
> > > > > >
> > > > > > Well, there's more than 30 years of production apps out there running
> > > > > > flavors of MUMPS, PICK, and others from which the jury could gather
> > > > > > data.
> > > > >
> > > > > They already have done so, and they already know why they work
> > > > > efficiently under certain circumstances, and under which circumstances
> > > > > they have problems.
> > > >
> > > > I've tried to find those "they" people to see what they have found out.
> > > > Can you point to one study out there that compares Pick with SQL-based
> > > > products? What is out there that compares any non-SQL (or SQL as a
> > > > second language) databases with SQL DBMS's without using SQL against
> > > > the non-SQL database? I'm apparently doing a lousy job of searching.
> > > > I'm not looking for theory on this one, but actual studies of real
> > > > software solutions. It does seem like there would be such, but I'm not
> > > > finding 'em.
> >
> > > I don't know any, nor do I expect something like that to exist. Such
> > > comparisons are difficult because of several reasons. The claims of the
> > > RM are mainly wrt. the functioning of an IT department as a whole
> > > within a certain type of context. That is hard to recreate in an
> > > experiment.
> >
> > OK, so you told me the jury was out regarding modeling and implementing
> > with non-1NF data (or something like that); then I told you that there
> > are production systems out there, if the jury really wanted to know;
> > then you said they have already gathered data; then I tried to ask
> > "where is it?"; and you said "I don't know any, nor do I expect
> > something like that to exist."
> >
> > So, I think we talked past each other on that one. If RVAs and other
> > non-1NF structures are now accepted in theory and implemented in
> > practice, then when should they be used?
>
> I'm confused by this statement Dawn. My understanding is as follows:
>
> 1NF is definitional in that it is simply a case of saying that
> "everything must be stored as tuples", allowing sets of such to form
> relations.
> By definition, mathematical relations may not have variable
> cardinalities across tuples and hence (but only as a consequence)
> applying 1NF means that each field must be guaranteed to occur but
> once.
>
> However, an element in a tuple may happily be a set, a list, a RVA or
> whatever user defined type one wishes to use and still be 1NF,
> as one
> can still form acceptable tuples with them. Currently one has to
> manipulate these user defined types externally as the tools aren't
> really there to do otherwise (apart from strings and date types).
>
> Is this not how you see it? All best, J.
Cheers! --dawn Received on Tue May 02 2006 - 02:21:44 CEST