Re: Normalize until neat, Automate until Complete
From: Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be>
Date: Wed, 24 Nov 2004 23:21:21 GMT
Message-ID: <RH8pd.34656$_Q1.1681466_at_phobos.telenet-ops.be>
>
> I should have pointed out when asking this question that I am aware of the
> use of derivations in views and selects, what I have never found is any
> systematic treatment of their inclusion in tables, except for the donning
> of scary masks and a lot of dancing around howling, "away evil spirits,
> begone!"
Date: Wed, 24 Nov 2004 23:21:21 GMT
Message-ID: <RH8pd.34656$_Q1.1681466_at_phobos.telenet-ops.be>
Kenneth Downs wrote:
> Kenneth Downs wrote:
>> >>hmmm, I must be one of those practitioners who has only a shallow >>understanding of the theory. As far as I can tell, relational algebra and >>relational calculus are both about querying existing data (though I am >>willing to be corrected). Under what terms might I find the theoretical >>foundation for the *generation* of information out of other information?
>
> I should have pointed out when asking this question that I am aware of the
> use of derivations in views and selects, what I have never found is any
> systematic treatment of their inclusion in tables, except for the donning
> of scary masks and a lot of dancing around howling, "away evil spirits,
> begone!"
I doubt that there are any hard and fast rules here. It's obvious that there is a trade-off in the sense that more derived data makes certain updates slower and certain queries faster (possibly including those that are needed that check constraints). Where the optimum lies is of course very much dependent upon the particular sitation you are in.
- Jan Hidders