[tz] So, about those LMT offsets

[Steve Allen]

On Sat 2021-05-22T16:56:53-0400 Tom Lane via tz hath writ:
> The reason I suggest this is that we regularly get questions on
> the Postgres lists from novices who are confused by this behavior
> (pardon the SQL-isms):
>
> postgres=# set timezone = 'UTC';
> SET
> postgres=# select timestamptz '1884-01-01 12:00 America/New_York';
>       timestamptz
> ------------------------
>  1884-01-01 17:00:00+00
> (1 row)
>
> This is, of course, saying that noon in New York translates to
> 1700 UT ...
>
> postgres=# select timestamptz '1883-01-01 12:00 America/New_York';
>       timestamptz
> ------------------------
>  1883-01-01 16:56:02+00
> (1 row)
>
> ... uh, what?  The novices are definitely not expecting that,

> and they don't find it helpful.  We have to explain it away
> as "that's what tzdb says", but it's still unhelpful.

It serves to remind folks that there is a point in time before which
the question they think they asked has no meaning; that if they want
precise time before then they will have to decide what question they
are trying to answer.

--
Steve Allen                    <sla at ucolick.org>              WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat  +36.99855
1156 High Street               Voice: +1 831 459 3046         Lng -122.06015
Santa Cruz, CA 95064           https://www.ucolick.org/~sla/  Hgt +250 m