Re: [PATCH] Negative Transition Aggregate Functions (WIP)

On Sun, Dec 15, 2013 at 2:27 PM, Josh Berkus <josh(at)agliodbs(dot)com> wrote:

> If we're going to disqualify NUMERIC too, we might as well bounce the
> feature. Without a fast FLOAT or NUMERIC, you've lost most of the
> target audience.
>
>
I don't agree with this. I'm going with the opinion that the more types and
aggregates we can support (properly) the better. I'd rather delay
implementations of the ones which could change results than see them as a
roadblock for the ones we can implement today without this danger.

I think the feature is worth it alone if we could improve COUNT(*).
It's a bit silly to have to loop through all the tuples in a tuplestore to
see how many there are after removing one, when we already knew the count
before removing it. Something like, 10 - 1 .... ummm I dunno, let's count
again.. 1, 2, 3, 4, 5, 6, 7, 8, 9.... It's 9!! Where with this patch it's
just 10 - 1 *result*. Feels a bit like asking a kid, if you have 10 beans
and you take 1 away, how many will there be. You and I know 9, but the kid
might have to count them again. PostgreSQL counts them again.

Regards

David Rowley

--
> Josh Berkus
> PostgreSQL Experts Inc.
> http://pgexperts.com
>