Re: A question for Mr. Celko

Jan Hidders <jan.hidders_at_REMOVETHIS.pandora.be> wrote in message news:<pan.2004.07.20.21.14.55.18862_at_REMOVETHIS.pandora.be>...
> On Tue, 20 Jul 2004 18:15:29 +0100, Paul wrote:
> > John Jacob wrote:
> >> [...] What about UNNESTing a relation-valued attribute is different
> >> from extraction? [...]
> >
> > UNNESTing is part of the relational engine whereas extraction is part of
> > the type engine?
> >
> > So from the point of view of the relational engine the value should be
> > atomic, but from the viewpoint of the type engine this doesn't have to
> > be the case.
>
> Well put! :-) Do you require more explanation John?

I think I got more out of the other branch than this one. I'm not at all sure I see how something could be in the "type engine" and not in the "relational engine." Seems to me the relational engine is the implementation of the type engine, the two are inseparably connected, and if I could model extraction of RVA's in the type system, certainly I would have to provide an implementation for that functionality in the relational engine.

I'm going to have to think a long time about this one, but I'm still not swayed that the complexity isn't worth it. "That sounds hard" never stopped us before :)

While I'm thinking about it all, do you have any links to research regarding the complexity you're describing?

Regards,
Bryn Received on Wed Jul 21 2004 - 06:12:21 CEST