On 3/29/21 2:48 PM, Bryn Llewellyn wrote:
On 27-Mar-2021, at 01:42, Francisco Olarte <fola...@peoplecall.com> wrote:
Bryn, ( 1st, sorry if I misquote something, but i use text-only for the list
)...
Thanks again, Francisco. You said several things that clarify my understanding.
Re your comment:
I've never tried to make some thing as complex as what you seem to be trying…
What I’m trying to do is to understand interval semantics so that I can write a
clear account of this topic. I do find the PostgreSQL doc on the topic
difficult to use for this purpose because information is scattered and (as you
said) it’s a dense read. This is why (though I don’t like the approach) I’m
amassing empirical observations and trying to fit a mental model to what I
observe.
Re your comment:
I'm completely lost with the horological/cultural things…
My claim is that there’s a genuine distinction to be drawn in the conceptual
domain—and that this can be made independently of any particular computer
system. I might say that “1 day” is simply the same thing as “24 hours”, in
the same way that “1 foot” is the same as “12 inches”. But my discussion
partner might argue with this saying that the length of one day is sometimes 23
hours and sometimes 25 hours due to the much-rehearsed arguments about DST.
Here, I’d be thinking horologically and my discussion partner would be thinking
culturally. Those two terms of art (or other equivalent ones) are useful to
stop a fist fight breaking out by allowing each discussion partner to
understand, and label, the other’s mental model—both of which have merit.
The point is horology is cultural, see non-Western calendars and
alternate time keeping methods. Trying to maintain a distinction between
the two concepts only furthers the confusion. The inconsistencies you
see are the result of one(culture) intervening in the other(horology).
Notice that the same argument could be had about the equivalence of “1 minute”
and “60 seconds” in the light of the “leap second” phenomenon. It just happens
that when we get to PostgreSQL, its Proleptic Gregorian Calendar implementation
knows nothing of leap seconds. At least, this is how I interpret “because leap
seconds are not handled” on the
https://www.postgresql.org/docs/11/functions-datetime.html page.
--
Adrian Klaver
adrian.kla...@aklaver.com
