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

[Guy Harris]

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 because they don't like sonic.net, or something, so I'm resending this to the list, *without* CCing Tom, in the hopes that it'll get delivered to him via the list, in a fashion more acceptable to the machine in question.

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.

So I shouldn't run Postgres on any Mac that I can conveniently carry while it's running, because if I carry the Mac into a car, train, airplane, or boat, the system's active time zone might change out from under Postgres. :-)

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