Re: Timestamp precision and rounding

On Thu, 3 Jun 2004, Jeff Boes wrote:

> (asked last week on .questions, no response)
>
> Can anyone explain why this happens?  (under 7.4.1)
>
>     select '2004-05-27 09:00:00.500001-04' :: timestamp(0) ;
>
>           timestamp
>     ---------------------
>      2004-05-27 09:00:01
>
>
>     select '2004-05-27 09:00:00.500000-04' :: timestamp(0) ;
>
>           timestamp
>     ---------------------
>      2004-05-27 09:00:00
>
>
> That is, why doesn't the second operation result in the same timestamp
> as the first? Is it a floating-point representation issue, or are the
> mathematical rules of rounding not being followed correctly (as I
> understand them, anyway)?

My first guess would be that your system probably implements its default
rounding as nearest even for .5 results, what does 9:00:01.5 give you?