Re: more on delete from join

From: paul c <>
Date: Wed, 02 Sep 2009 14:48:11 GMT
Message-ID: <LAvnm.43501$PH1.19390_at_edtnps82>

Joe Thurbon wrote:
> On Wed, 02 Sep 2009 15:54:21 +1000, Marshall <>
> wrote:

>> I also disagree with the notion that the database state before
>> an update is a "premise" and the state after is a "conclusion."

> I thought that Kevin was saying that a base relvar is like a premise and
> a view is like a conclusion ...
> ...

Relation values are both formed by the same operators. Or is it just relvars, pointers to values, that are of two kinds, not relations? If that is the case, then maybe the subject should be renamed 'relvar theory' or 'relvar model'. What makes one different from the other? Less "true"? The fact that one references other relations even though every constraint is a reference to a relation? Because some people think one's extension is stored and the other isn't, so one is optimized and the other isn't, even though both are recorded? How is storing different from recording? Why does a physical language even need a "base" or "virtual" keyword? Or is it just that the logic of "base" updating was fumbled in the first place (eg., the physical optimization of delete has become confused with the logic of delete) and when the optimization was found to not seem to work with views people concluded that views are different kinds of relations, if so how does type/typist theory react? If nobody can say what is the material difference, the difference must be mystical. It would be better to ask what is the difference between physical and logical. Received on Wed Sep 02 2009 - 16:48:11 CEST

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