| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Thomas Munro <thomas(dot)munro(at)gmail(dot)com> |
| Cc: | ysangkok(at)gmail(dot)com, Pg Docs <pgsql-docs(at)lists(dot)postgresql(dot)org> |
| Subject: | Re: Second-granular timezone offset format not documented |
| Date: | 2021-07-05 14:04:27 |
| Message-ID: | 1438453.1625493867@sss.pgh.pa.us |
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| Lists: | pgsql-docs |
Thomas Munro <thomas(dot)munro(at)gmail(dot)com> writes:
> As for whether it's valid, that's coming from the IANA tz dataset. It
> has a moment that it believes standard time to have begun at each
> location, in this case:
> Z America/Mexico_City -6:36:36 - LMT 1922 Ja 1 0:23:24
> https://en.wikipedia.org/wiki/Time_in_Mexico#History seems to agree on
> the year at least. That "local mean time" offset is computed from the
> location's longitude, for lack of anything better. The tzinfo
> "Theory" file has a bunch of disclaimers about pre-1970 data though,
> including "the tz database's LMT offsets should not be considered
> meaningful".
I tried to interest them in dropping the LMT idea altogether [1].
Unsurprisingly, the proposal went nowhere.
regards, tom lane
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