Re: Planned obsolescence in identify_system_timezone()

"Tom Lane" <tgl(at)sss(dot)pgh(dot)pa(dot)us> writes:

> I just noticed that identify_system_timezone() tries to match our
> timezones to the system timezone on the basis of probing the date
> range 1904-2004. While doubtless this seemed like a good idea at
> the time, it means that we'll be unable to distinguish zones whose
> histories diverge after 2004. I think there are some already,
> and certainly there are likely to be some in future. I propose
> modifying this logic to test 100 years back from the current year,
> instead. Any objections? Should such a change be back-patched?

Seems obvious in retrospect. Or perhaps it should just always go back to about
1900 which is when a lot of places adopted standard timezones.

> I'm also more than slightly tempted to modify the code so that it will
> always reject a match to the "Factory" zone (and fall back to regular
> "GMT" instead). The logging behavior illustrated here:
> http://archives.postgresql.org/pgsql-bugs/2008-06/msg00191.php
> seems just completely bletcherous to me. It's not our business
> to nag the user into setting up /etc/localtime, and even if it
> were, this is obviously an ineffective way to do it ;-)
> Any objections to that one?

If we're going to do it at all it should be once at startup (or config file
read or some event like that). But I think I agree that it's just not our
place at all and just defaulting to GMT is the right option.

--
Gregory Stark
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