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

On 1/10/14, 1:07 PM, Tom Lane wrote:
> Florian Pflug<fgp(at)phlo(dot)org> writes:
>> >On Jan10, 2014, at 19:08 , Tom Lane<tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>>> >>Although, having said that ... maybe "build your own aggregate" would
>>> >>be a reasonable suggestion for people who need this? I grant that
>>> >>it's going to be a minority requirement, maybe even a small minority
>>> >>requirement. People who have the chops to get this sort of thing right
>>> >>can probably manage a custom aggregate definition.
>> >So we'd put a footgun into the hands of people who don't know what they're
>> >doing, to be fired for performance's sake, and leave it to the people
>> >who know what they are doing to put the safety on?
> If I may put words in Kevin's mouth, I think his point is that having
> float8 sum() at all is a foot-gun, and that's hard to deny. You need
> to know how to use it safely.

And IMHO if you've got something that's going to produce bad data if you do it wrong, I'd rather that the error be as large as possible so that you're more likely to discover it and fix it...
--
Jim C. Nasby, Data Architect jim(at)nasby(dot)net
512.569.9461 (cell) http://jim.nasby.net