Horton

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

Christoph Berg <myon@debian.org>

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From: Christoph Berg <myon@debian.org>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2019-06-14T09:55:46Z
Lists: pgsql-hackers 
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?

> So I'm still mystified by Christoph's report, and am forced to suspect
> pilot error -- specifically, /etc/localtime not containing what he said.

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'

Same behavior on Debian Stretch (stable):
lrwxrwxrwx 1 root root 27 Mai  7 11:14 /etc/localtime -> /usr/share/zoneinfo/Etc/UTC

$ grep timezone pgdata/postgresql.conf
log_timezone = 'UCT'
timezone = 'UCT'

$ grep timezone pgdata/postgresql.conf
log_timezone = 'Etc/UTC'
timezone = 'Etc/UTC'

> 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.

Christoph

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.