Re: Idempotence and "Replication Insensitivity" are equivalent ?

From: vc <>
Date: 23 Sep 2006 09:50:19 -0700
Message-ID: <>

Chris Smith wrote:
> <> wrote:
> > For some reason some of you guys want to stick to a definition that is
> > proving to be too strict, not even coerent since treat AVG and MEDIAN
> > are treated differently (I have shown that conceptually they are both
> > systesis of a distribution). Not practical.
> Pamela,
> Please reflect on what you're doing. You are coming into a newsgroup on
> database theory (and then adding one on math; and yes, you added it);
> and then telling us that you don't know anything about database theory;
> and subsequently complaining that the standard formulation of aggregate
> functions is wrong.

What is the standard formulation of aggregate functions ? Where can one find such formulations (private attempts do not qualify) ?

> It's not wrong. It is widely known and accepted
> that the median calculation fits poorly, if at all, into the category of
> aggregate functions.

Do you have a reference for the non-acceptance of the median function ?  What about standard deviation ?

>You insist on acting like this result is an
> invention of the people you are speakig to on this newsgroup; in fact,
> it is probably older than I am.
> If you think that query languages should have a median function, and
> that it should look just like an aggregate function, then fine. You can
> choose a DBMS that does so, or even write a DBMS that does so if you are
> so inclined. It remains true that your syntactic similarity has nothing
> to do with aggregate functions, and that your implementation of the
> function will look extremely different from a reasonable implementation
> of any aggregate function.

What is a "reasonable implementation of any aggregate function" and assuming there is such, what has the implementation got to do with the abstract notion of aggregate function ? Received on Sat Sep 23 2006 - 18:50:19 CEST

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