Re: BUG #1993: Adding/subtracting negative time intervals

On Tue, 25 Oct 2005 13:28:00 -0400, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
> regression=# select '2005-10-29 13:22:00-04'::timestamptz + '1 day'::interval;
> ?column?
> ------------------------
> 2005-10-30 13:22:00-05
> (1 row)
>
> regression=# select '2005-10-30 13:22:00-05'::timestamptz - '2005-10-29 13:22:00-04'::timestamptz;
> ?column?
> ----------------
> 1 day 01:00:00
> (1 row)
>
> ISTM that given the former result, the latter calculation ought to
> produce '1 day', not something else.

Would the '1 day' result know it was 24 hours or be the new 23/24/25
hour version of '1 day'?

If it was the new version, could you get the original values back?
i.e. what would be the result of
select
('2005-10-29 13:22:00-04'::timestamptz +
('2005-10-30 13:22:00-05'::timestamptz -
'2005-10-29 13:22:00-04'::timestamptz)) at time zone 'EST';

klint.

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