Horton

Re: UCT (Re: pgsql: Update time zone data files to tzdata release 2019a.)

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Christoph Berg <myon@debian.org>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2019-06-14T13:11:15Z
Lists: pgsql-hackers 
Christoph Berg <myon@debian.org> writes:
> Re: Tom Lane 2019-06-11 <24452.1560285699@sss.pgh.pa.us>
>> The only way I can get it to pick "Etc/UCT" is if that's what I put
>> into /etc/localtime.  (In which case I maintain that that's not a bug,
>> or at least not our bug.)

> Did you try a symlink or a plain file for /etc/localtime?

Symlink --- if it's a plain file, our code can't learn anything from it.

> On Debian unstable, deleting /etc/timezone, $TZ not set, and with this symlink:
> lrwxrwxrwx 1 root root 27 Mär 28 14:49 /etc/localtime -> /usr/share/zoneinfo/Etc/UTC

> /usr/lib/postgresql/11/bin/initdb -D pgdata
> $ grep timezone pgdata/postgresql.conf
> log_timezone = 'UCT'
> timezone = 'UCT'

> /usr/lib/postgresql/12/bin/initdb -D pgdata
> $ grep timezone pgdata/postgresql.conf
> log_timezone = 'Etc/UTC'
> timezone = 'Etc/UTC'

That's what I'd expect.  Do you think your upthread report of HEAD
picking "Etc/UCT" was a typo?  Or maybe you actually had /etc/localtime
set that way?

>> Anyway, moving on to the question of what should we do about this,
>> I don't really have anything better to offer than back-patching 23bd3cec6.

> The PG12 behavior seems sane, so +1.

OK, I'll make that happen.

			regards, tom lane

Commits

  1. Tweak our special-case logic for the IANA "Factory" timezone.

  2. Avoid choosing "localtime" or "posixrules" as TimeZone during initdb.

  3. Prefer timezone name "UTC" over alternative spellings.

  4. Attempt to identify system timezone by reading /etc/localtime symlink.

  5. Update time zone data files to tzdata release 2019a.