Re: Idempotence and "Replication Insensitivity" are equivalent ?

From: <>
Date: 21 Sep 2006 03:40:07 -0700
Message-ID: <>

Chris Smith ha scritto:

> Marshall <> wrote:

> I suppose no one could say you were wrong, but then COUNT would become
> impossible to define under such a system.

While this whole discussion about properties of functions defined is some (involved) way is fashinating and may have some pure math interest,

I believe that to the purpose of dbms aggregate functions it is of little importance.

What I think I have heard let's not consider COUNTDISTINCT an aggregate function just because it does not fit in our fashinating math contruction
would make laugh any dbms user ...

As I view it, the main concern, if any, should be put on computational aspect.

I think that in practice a DBMS should implement, "by default",  all the interesting aggregate functions that can be computed "in some efficient way".

In addition it must give the possibility to the user, through custom code,
to specify "any" aggregate function he wishes.

And here I literally mean anything. Anything that can be coded. It's up to the user to spend it's time as he wishes.

I would find much more interesting to discuss here what means "interesting" and "efficient way" (to decide about the "default aggregate functions").

Does it means bounded CC, does it means restrictions to memory, does it mean that we should be able to process any stream of data without any post processing , ... ?

What is your opinion ?


> Chris Smith
Received on Thu Sep 21 2006 - 12:40:07 CEST

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