Re: In an RDBMS, what does "Data" mean?

In message <c94id4$ua1$1_at_news.netins.net>, Dawn M. Wolthuis <dwolt_at_tincat-group.com> writes
>"Paul" <paul_at_test.com> wrote in message
>news:gfjtc.7896$wI4.912834_at_wards.force9.net...
>> Anthony W. Youngman wrote:
>> > So if you use Newtonian Mechanics to prove where Mercury was 400 years
>> > ago, your proof is more accurate than Tycho Brahe's observations - which
>> > place it somewhere else?
>>
>> The proof will still be 100% accurate.
>> Newtonian Dynamics assumes certain axioms, which we now know to be
>> slightly wrong.
>
>If talking about mathematical axioms, they are not right or wrong -- they
>just are. It is the use of those axioms in some setting or another that
>could be inappropriate, not useful, or lead one to draw incorrect
>conclusions due to applying a poor mathematical analogy (metaphor) to the
>situation.
>
>> The first-order logic is still perfectly accurate; it's
>> just your starting assumptions have changed.
>
>So the mathematics is right, but the science is wrong -- and I think that is
>a major point of this thread.
>
>> > You are making exactly the mistake that made me start this thread - you
>> > are assuming that the DBMS *defines* reality, rather than carrying out
>> > experiments to show that the DBMS accurately *describes* reality.
>> >
>> > What you should have said is "IF the dbms is an accurate model of real
>> > life then ...". Which is basically what I said - if the dbms and real
>> > life disagree then the dbms model must be wrong. You seem to be saying
>> > that it's reality that's wrong ...
>>
>> I'm just talking about the system of logic that enables us to talk about
>> our database (our "theory" if you like). Whether our theory has axioms
>> that correspond to the real world, or whether our interpretation (or
>> "model") of our theory is accurate, is a totally different question.
>
>Exactly -- so I think you and Wol (and I) are in agreement on that. It is
>why whenever anyone suggests that the best way to set up a databases is by
>employing relational theory BECAUSE relational theory is based on
>mathematics, I laugh (then cry). I have an appreciation of what mathematics
>is and what it isn't. How do we determine whether a mathematical model is a
>good metaphor for what we are doing? We have to step outside of mathematics
>to do that. So, the proof that various aspects of relational theory have
>been good for use with DBMS's is not within mathematics.

Thanks, Dawn. It was Laconic, I think, who gave that wonderful quote about "the axioms are self-evident, the logic is flawless, therefore the experiments must be wrong" :-)

That's why you and I tear our hair out when people say relational is best because it's based on mathematics! They're the people who assume the axioms are self evident ...

And I think that's a major failing in current RDBMS thinking - nobody is questioning the axioms. Unfortunately, to me, they are self-evidently wrong...

Cheers,
Wol

-- 
Anthony W. Youngman - wol at thewolery dot demon dot co dot uk
HEX wondered how much he should tell the Wizards. He felt it would not be a
good idea to burden them with too much input. Hex always thought of his reports
as Lies-to-People.
The Science of Discworld : (c) Terry Pratchett 1999