Re: Have I found an interval arithmetic bug?

On Mon, Apr 5, 2021 at 02:01:58PM -0400, Bruce Momjian wrote:
> On Mon, Apr 5, 2021 at 11:33:10AM -0500, Justin Pryzby wrote:
> Well, bug or not, we are not going to change back branches for this, and
> if you want a larger discussion, it will have to wait for PG 15.
>
> > > https://www.postgresql.org/docs/current/datatype-datetime.html#DATATYPE-INTERVAL-INPUT
> > > « …field values can have fractional parts; for example '1.5 week' or '01:02:03.45'. Such input is converted to the appropriate number of months, days, and seconds for storage. When this would result in a fractional number of months or days, the fraction is added to the lower-order fields using the conversion factors 1 month = 30 days and 1 day = 24 hours. For example, '1.5 month' becomes 1 month and 15 days. Only seconds will ever be shown as fractional on output. »
>
> I see that. What is not clear here is how far we flow down. I was
> looking at adding documentation or regression tests for that, but was
> unsure. I adjusted the docs slightly in the attached patch.

Here is an updated patch, which will be for PG 15. It updates the
documentation to state:

The fractional parts are used to compute appropriate values for the next
lower-order internal fields (months, days, seconds).

It removes the flow from fractional months/weeks to
hours-minutes-seconds, and adds missing rounding for fractional
computations.

--
Bruce Momjian <bruce(at)momjian(dot)us> https://momjian.us
EDB https://enterprisedb.com

If only the physical world exists, free will is an illusion.