Re: Timezone database changes

>>> On Mon, Oct 8, 2007 at 10:48 PM, in message
<200710090348.l993mOG15547@momjian.us>, Bruce Momjian <bruce@momjian.us> wrote:
> I had a thought a week ago.  If we update the time zone database for
> future dates, and you have a future date/time stored, doesn't the time
> change when the time zone database changes.
>
> For example if I schedule an appointment in New Zealand for 10:00a and
> we change the time zone database so that date is now daylight savings,
> doesn't the time change to display as 9 or 11am?  That seems pretty bad.
It depends.  It's what you want if you are looking to point your telescope
to the right part of the sky or to be on an international conference call
which isn't going to be rescheduled because of New Zealand's daylight
saving time rules; but, as you point out, not usually what you want for a
local appointment.
We use TIMESTAMP WITH TIME ZONE to capture a moment in the natural stream
of time, and separate DATE and TIME WITHOUT TIME ZONE to capture local
appointments.  I believe this gives the desired behavior both with
ANSI/ISO standard behavior and with the PostgreSQL implementation.
-Kevin