Re: does a table always need a PK?

"Heikki Tuuri" <Heikki.Tuuri_at_innodb.com> wrote in message news:Vew2b.4177$G37.1909_at_read3.inet.fi...
> Lee,
>
> "Lee Fesperman" <firstsql_at_ix.netcom.com> kirjoitti viestissä
> news:3F4A7F1D.291C_at_ix.netcom.com...
> > Bob Badour wrote:
> > >
> > > "Heikki Tuuri" <Heikki.Tuuri_at_innodb.com> wrote in message
> > > news:GEg2b.11$G37.0_at_read3.inet.fi..
> > > > 2 years ago we discussed the 'correct' definition of 'relational' in
> > > > comp.databases.theory with several people. I think the concept is
> vague.
> > > > For example, Codd's 12 principles are not formulated as mathematical
> axioms.
> > >
> > > Read the 1970 ACM paper instead of 12 rules of thumb.
> >
> > Forget it, Bob. He has a commercial interest in claiming that the
> Relational Model is
> > vague.
>
> if I can recall, the 1970 paper is not formulated as mathematical axioms
> either. Or is it? Do you remember?

rtfm: http://www.acm.org/classics/nov95/

> Codd accepts NULLs while Date disapproves. How can 'the relational model'
be
> clear if there are differences like this?

Missing information has no theory-based solution. Codd proposed two markers and 4VL as an ad hoc solution to the problem of missing information. His proposal is ad hoc without any theoretical foundation and is fraught with problems. Others have similarly proposed other ad hoc solutions to the problem, but all of the proposals so far are ad hoc without any theoretical foundation. Hence, all of the proposals dealing with missing information are controversial.

The principle of cautious design would argue for considering any mechanism dealing with missing information as experimental or proprietary--including SQL's NULL and 3VL.

I have long argued that adequate support for user defined types and for adequate physical independence would give me all the tools I really need to devise my own ad hoc solutions. My own ad hoc solutions would be guaranteed consistent because I would have to construct them on a theory based structural framework consisting of relations and a formal, extensible type system.

> Lee, of course, has a commercial interest in claiming that 'a/the
relational
> model' is crystal clear. He tries to market FirstSQL on that basis.

Lee has always made his commercial interest in FirstSQL very clear. I have fenced intellectually with Lee over the issue of missing information for... is it really a decade now?!? Wow! Time flies.

Unlike most vendors, Lee is actually knowledgeable and honest about the nature and the limitations of his product's solution to missing information. FirstSQL supports Codd's two markers and 4VL for those who are curious.

I never had any illusions that I would convince Lee to change his product to abandon 4VL just as I have no illusions about your ability and willingness to educate yourself on the fundamentals of data management.

> "* FirstSQL/J Object/Relational DBMS "
>
> By the way, FirstSQL probably is not Codd-12-relational? Why do you claim
it
> to be an 'object/relational' database then? Is it 'Lee
> Fesperman -relational'?

It was me who pointed out SQL is not particularly relational--not Lee. FirstSQL, of course, suffers some of the same problems all SQL dbmses suffer. Unlike MySQL, I would count FirstSQL a dbms or at least a significant subset of such a system.

> > He has stubbornly refused to educate himself, clinging to 'thumbnail'
> > descriptions of the relational model.
>
> No, not at all. I looked at the 1970 paper 1.5 years ago.

Looking and learning are two different things. If you know what is in the 1970 paper, why would you argue that the 12 rules are insufficiently formal? The 1970 paper is the formal specification and the 12 rules are informal rules of thumb.

> > See Database Debunkings (www.dbdebunk.com) for a
> > glaring example.
>
> Well, that quote was taken from a discussion at comp.databases or .theory.
I
> did not remember then that Codd had mentioned integrity constraints in his
> 1970 paper.

It was in comp.databases almost two years ago to the day. Um, let's see... that means two years ago you were a database vendor who had never read Codd's paper and were spouting the most absurd, ridiculous nonsense. About six months later, you finally condescended to read the paper, and now you are a database vendor who claims to have read the paper and who continues to spout the most absurd, ridiculous nonsense. Is that an accurate summary?

> > --
> > Lee Fesperman, FirstSQL, Inc. (http://www.firstsql.com)
>
> Best regards,
>
> Heikki Tuuri
> Innobase Oy
> http://www.innodb.com
> Foreign keys, transactions, and row level locking for MySQL
> InnoDB Hot Backup - a hot backup tool for MySQL
>
>
Received on Tue Aug 26 2003 - 02:28:40 CEST