Horton

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

Andrew Gierth <andrew@tao11.riddles.org.uk>

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From: Andrew Gierth <andrew@tao11.riddles.org.uk>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Christoph Berg <myon@debian.org>, PostgreSQL Hackers <pgsql-hackers@postgresql.org>
Date: 2019-06-04T15:57:03Z
Lists: pgsql-hackers 
>>>>> "Tom" == Tom Lane <tgl@sss.pgh.pa.us> writes:

 > Andrew Gierth <andrew@tao11.riddles.org.uk> writes:
 >> I believe I pointed out a long, long time ago that this tie-breaking
 >> strategy was insane, and that the rule should be to prefer canonical
 >> names and use something else only in the case of a strictly better
 >> match.

 Tom> This is assuming that the tzdb data has a concept of a canonical
 Tom> name for a zone, which unfortunately it does not. UTC, UCT,
 Tom> Etc/UTC, and about four other strings are equivalent names for the
 Tom> same zone so far as one can tell from the installed data.

The simplest definition is that the names listed in zone.tab or
zone1970.tab if you prefer that one are canonical, and Etc/UTC and the
Etc/GMT[offset] names could be regarded as canonical too. Everything
else is either an alias or a backward-compatibility hack.

-- 
Andrew (irc:RhodiumToad)

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.