Re: BUG #17496: to_char function resets if interval exceeds 23 hours 59 minutes

At Thu, 14 Jul 2022 17:57:32 -0400, Bruce Momjian <bruce(at)momjian(dot)us> wrote in
> On Tue, May 24, 2022 at 01:11:45PM -0700, Nathan Bossart wrote:
> > The documentation for this function indicates HH24 can output hour values
> > higher than 23∴
> >
> > <function>to_char(interval)</function> formats <literal>HH</literal> and
> > <literal>HH12</literal> as shown on a 12-hour clock, for example zero hours
> > and 36 hours both output as <literal>12</literal>, while <literal>HH24</literal>
> > outputs the full hour value, which can exceed 23 in
> > an <type>interval</type> value.
> >
> > I see different results depending on how I define the interval:
> >
> > postgres=# select to_char(INTERVAL '1 day', 'HH24:MI');
> > to_char
> > ---------
> > 00:00
> > (1 row)
> >
> > postgres=# select to_char(INTERVAL '24h', 'HH24:MI');
> > to_char
> > ---------
> > 24:00
> > (1 row)
> >
> > The example provided is more like the former (no hour value), because
> > "timestamp - timestamp" converts 24-hour intervals into days. In general,
> > I agree that this probably not a bug. You probably want to ask to_char()
> > to display the days as well..

On the other hand, "interval + interval" doesn't convert hours into
days. I expected the math to do normalization.

select INTERVAL '1 day 15hour' + interval '2 day 15 hour';
?column?
-----------------
3 days 30:00:00

Is there any means to control over normalization?

> select normalize_interval('3 days 30:00:00'::interval, 'HH24:MI')
> 102:00
> select normalize_interval('3 days 30:00:00'::interval, 'DD HH24:MI')
> 4 04:00
> select normalize_interval('3 days 30:00:00'::interval, 'HH12:MI')
> ERROR: hours out of range

> Well, if we did that then this would be odd:
>
> SELECT to_char(INTERVAL '2 day', 'DD HH24:MI');
> to_char
> ----------
> 02 00:00
>
> or this:
>
> SELECT to_char(INTERVAL '2 day 4 hours', 'DD HH24:MI');
> to_char
> ----------
> 02 04:00

Mmm. I don't see this is odd...

--
Kyotaro Horiguchi
NTT Open Source Software Center