[tz] Breach of tzdb charter: Merging timezones is not within the charter

Tom Lane tgl at sss.pgh.pa.us
Thu Jun 3 22:28:37 UTC 2021

"Clive D.W. Feather via tz" <tz at iana.org> writes:
> Since most zones in the database are amalgamations of pre-1970 zones, such
> "inaccuracies" have always been there and some people in the zone would
> have not said they were correct. So what? As far as I can see, the zones
> are accurate for all of their area post-1970 and part of their area
> pre-1970. This change doesn't alter that.

As far as I've understood, the loudest complaints are precisely
because that isn't true.  For example, the pre-1970 data for
Europe/Stockholm would no longer be correct for any part of Sweden.

My own concern is a shade more nuanced.  Paul has stated that the
tzdb results don't change as long as you were including backzone both
before and after.  (I haven't checked that, but I have no reason to
doubt it.)  However, the Postgres project is finding itself in a hard
place precisely because we *didn't* adopt backzone.  We reasoned that
the default set of zones was the preferred thing and thus would be the
most likely to remain stable.  Now, not only is the default different
(which perhaps we could live with), but there's no way at all to get
the old default.  That's not okay, and it seems to me to fly in the
face of most understandings of software backwards compatibility,
never mind any tzdb-specific rules.

			regards, tom lane

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