Andrew - Supernews <andrew+nonews@supernews.com> writes:
> Um, what? Under what conditions is it permissable for simple arithmetic on
> (only) timestamptz values (which may have originated in different timezones
> neither of which is the current one) to be dependent on the current timezone
> setting?
Timestamp subtraction will give different answers depending on whether
there's a DST adjustment in between.
regression=# select '2005-10-31'::timestamptz - '2005-10-28'::timestamptz;
?column?
-----------------
3 days 01:00:00
(1 row)
regression=# set timezone = 'Japan';
SET
regression=# select '2005-10-31'::timestamptz - '2005-10-28'::timestamptz;
?column?
----------
3 days
(1 row)
BTW, if we were doing subtraction symbolically as I think we should,
these *would* give the same answer, ie, '3 days' in both cases. Care to
rethink your opposition to that idea?
regards, tom lane