[tz] NetBSD vs Darwin timezone API (was: tzdata2016g missing version info)

Tom Lane tgl at sss.pgh.pa.us
Fri Nov 11 03:52:58 UTC 2016

Guy Harris <guy at alum.mit.edu> writes:
> On Nov 10, 2016, at 3:17 PM, Tom Lane <tgl at sss.pgh.pa.us> wrote:
>> FWIW, I beg to differ on that.  I know this will break Postgres, which
>> is doing pretty much the same thing as Emacs, ie relying on a lot of calls
>> to localtime() to infer the system's active timezone.  We only do that
>> once during database initialization, so we're not badly exposed, but
>> nonetheless this is another data point suggesting that programs in the
>> field do have this assumption.

> Why does Postgres need to know the system's active time zone?

To select a reasonable default for the "timezone" setting.  As
I said, it only happens once during initialization, and it's probably
not very likely that you'd be running initdb while passing through a
zone boundary.  But it is an illustration that Emacs isn't the only
program out there that expects consistent results across multiple
localtime calls.

> This bounced with "Diagnostic-Code: SMTP; 551 5.7.1 Rejected due to SPF
> mismatch" when Tom was CCed, perhaps because my From: address's domain
> name isn't the same as my mail server's domain name, or

Sorry about that ... experimental spam filtering.  But you should think
twice about sending email claiming to be from an MIT address out of
servers that are not MIT's.  It's a good way to get blocked, and to
get your mail provider's servers blocked too.

			regards, tom lane

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