Re: Have I found an interval arithmetic bug?

On Sun, Apr 11, 2021 at 12:57 PM Zhihong Yu <zyu(at)yugabyte(dot)com> wrote:

>
>
> On Thu, Apr 8, 2021 at 10:24 AM Bruce Momjian <bruce(at)momjian(dot)us> wrote:
>
>> 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.
>>
>>
> +1 to this patch.
>

Bryn reminded me, off list, about the flowing down from fractional
day after the patch.

Before Bruce confirms the removal of the flowing down from fractional day,
I withhold my previous +1.

Bryn would respond with more details.

Cheers