Re: Idempotence and "Replication Insensitivity" are equivalent ?

Chris Smith ha scritto:

> <pamelafluente_at_libero.it> wrote:
Although you *can* define COUNT DISTINCT as
> an aggregate function, it is a dumb thing to do because you have to re-
> address all the problems you just finished addressing with the
> projection of relations. Project, then count the rows.

 I have problems to follow you here. Has I said I know nothing about  theory. Do not know what you mean by the term "projection of relations".
 Is it something simple to grasp?

>
> > Hmmm. I know nothing about dbms theory, except than practical stuff,
> > but if this has been proposed by someone, perhaps has been done
> > as a theorical model, just to study perhaps its formal properties.
> >
> > I am missing to see how all that could, for instance, change they way
> > I write my programs for aggregative functions.
>
> This is being posted to two newsgroups: comp.databases.theory and (now
> that you added it) sci.math.

I guess that replies get posted automatically to these gropu. Would it be correct to change the destinations?

 Neither newsgroup is concerned with
> talking about how you write your database programs. Are you now
> proposing that you popped in to comp.databases.theory, and then added
> sci.math as well, in order to NOT discuss database theory and instead
> ask something about writing SQL queries? I'm really confused about your
> goals at this point.

My original goal was actually to discuss a method to deal with report functions under value duplication and create the appropriate unions of subqueries, ad Business Objects does, but, actually, if I could grasp some concept useful to improve the programs it would be really nice !

-P
>
> --
> Chris Smith
Received on Thu Sep 21 2006 - 20:50:25 CEST