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

David Patte dpatte at relativedata.com
Thu Jun 3 22:45:08 UTC 2021

My understanding is that the backzone data is complete and up-to-date 
for each zone that ever existed. The new main zones are simply a summary 
of the current data for each unique current zone.

I see no problem with that and will only use the backzones now.

But if thats not the case, we will have to fork and abandon tz.

On 2021-06-03 18:28, Tom Lane via tz wrote:
> "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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