Re: Mazes, trees, and forests
Date: Mon, 26 Apr 2004 14:23:44 +0300
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"mAsterdam" <mAsterdam_at_vrijdag.org> wrote in message
> x wrote:
> > Why do you consider only the foreign-keys of R1 ?
> Following the forestify algorithm eventually all foreign
> keys will get their turn.
> > A user can connect any two relations on any two attributes of compatible
> > types.
> Sure, and by expanding along those lines every user can
> build his own forest.
> > Do you consider only the base relations or any relation ? ;-)
> Well, I did. With 'any relation': you mean every conceivable relation
> on a base?
> > How can someone (other than the user) predict for what pairs of
> > the join of two relations make sense ?
> Why would anyone *want* to predict that? Sensible types help, but beyond
> that ... could you clarify how this impacts the suspicions I mentioned
> in the first posts?
What do you mean by the "data expressed as trees" ?
Why there would be any loss in the "data expressed as trees" ?
Do you consider "the data in the database" is "the stored data" ?
I'm also considering that some "derived data" may be lost.
In my opinion, in a RDBMS the data is in the:
- names of the named relations
- names of the attributes
- values of the attributes of any relation (base or derived)
- integrity constraints
- formula that define a derived relation
- associations of the above
> > This is why a relational DBMS is different from other types of DBMSs.
> Do you mean to imply that with 'other types of DBMS' (historic I assume)
> can't connect as they please? I must be misreading you.
By "other type of DBMSs" I'm referring to "hierarchical" or "network"
Maybe they can connect as they please. But with what cost ? I was taught that one need to write long routines to achieve some "connections".
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