Re: Database design, Keys and some other things

David Cressey wrote:
> I've seen an interesting way of presenting this idea, or a similar one.
> The authors call what the database serves up 'opinions' rather than
> 'facts'. That is, 'in the opinion of the database, the employee with
> employee id 12345 has first name "Marshall" and last name "Spight"'.
> Or, 'in the opinion of the database, there is no employee with id 567890'.
> Or 'the database has no opinion as what Donald Trump's e-mail address might
> be, if he has one'.
> I find this enormously refreshing, especially when it comes to missing data.

I like that a lot. 'Facts' about the world are pretty subjective even within scientific fields. Opinion is a lot more apt (Way back in the thread, when I attempted to offer an example of the distinction that can be made between a tuple's properties and the attributes that make up the 'fact', one was confidence a measure - there is a lot of research currently being done in the area). Imo ;)

Marshall Spight wrote:
> I guess you're saying it's profound that there's
> nothing profound to be said about the relationship between
> internal and externa predicate. I guess I could buy that

The Hofstadter view has a lot in common with this interpretation - that information arises from data + intelligent processing (he highlights grooves on a record as an example of data, intricately patterned and organised, yet completely meaningless without that external translation). A db should facilitate making that translation as simple, and as accurate to the creator's orginal opinion, as possible.

> We were discussing whether there was a difference between
> the natures of external ids vs. surrogate keys. What is
> essential to this question is what their nature is. Generally
> we do not regard context-specific considerations as essential.

I'm not sure context is the right line. As far as a specific database is concerned a VIN is not a surrogate key, its a natural. And to me, well, that's the key distinction (no pun intended). A surrogate exists solely to help facilitate the internal predicate that you distinguished, and has nothing to do with the external predicate.

all best, J. Received on Sat Oct 01 2005 - 21:23:45 CEST