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

On Tue, May 24, 2022, 3:23 PM PG Bug reporting form <noreply@postgresql.org>
wrote:

The following bug has been logged on the website:

Bug reference: 17496
Logged by: Yankz
Email address: qubzen@gmail.com
PostgreSQL version: 13.7
Operating system: Mac Os
Description:

to_char function resets if interval exceeds 23 hours 59 minutes found at:

https://www.postgresql.org/docs/current/functions-formatting.html#FUNCTIONS-FORMATTING-TABLE

Tested for both 13 and 14 versions. Check here:

https://dbfiddle.uk/?rdbms=postgres_14&amp;fiddle=31f5d8b7e8dbf855e1907e6e8f01d5cf

I don't see how this is a bug. You told it not to display the days or
higher units, so it doesn't.

Cheers,

Jeff

On Tue, May 24, 2022 at 03:55:49PM -0400, Jeff Janes wrote:

On Tue, May 24, 2022, 3:23 PM PG Bug reporting form <noreply@postgresql.org>

to_char function resets if interval exceeds 23 hours 59 minutes found at:

https://www.postgresql.org/docs/current/functions-formatting.html#FUNCTIONS-FORMATTING-TABLE

Tested for both 13 and 14 versions. Check here:

https://dbfiddle.uk/?rdbms=postgres_14&amp;fiddle=31f5d8b7e8dbf855e1907e6e8f01d5cf

I don't see how this is a bug. You told it not to display the days or
higher units, so it doesn't.

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..

--
Nathan Bossart
Amazon Web Services: https://aws.amazon.com

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..

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

--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com

Indecision is a decision. Inaction is an action. Mark Batterson

At Thu, 14 Jul 2022 17:57:32 -0400, Bruce Momjian <bruce@momjian.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

On Fri, Jul 15, 2022 at 04:58:35PM +0900, Kyotaro Horiguchi wrote:

At Thu, 14 Jul 2022 17:57:32 -0400, Bruce Momjian <bruce@momjian.us> wrote in

On Tue, May 24, 2022 at 01:11:45PM -0700, Nathan Bossart wrote:

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?

Sure, justify_hours():

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

SELECT justify_hours(INTERVAL '1 day 15hour' + interval '2 day 15
hour');
justify_hours
-----------------
4 days 06:00:00

--
Bruce Momjian <bruce@momjian.us> https://momjian.us
EDB https://enterprisedb.com

Indecision is a decision. Inaction is an action. Mark Batterson