Re: Formatting problems with negative intervals, TO_CHAR

Jeff Boes <jboes@qtm.net> writes:
> This seems ... well, counter-intuitive at least:
> (using Pg 7.4.1)

> # select to_char('4 minutes'::interval -
> '5 minutes 30 seconds'::interval, 'mi:ss');

>   to_char
> ---------
>   -1:-3
> (1 row)

> Why is the trailing zero lost? Why are there two minus signs?

> I would expect '-1:30'.

Yeah, me too.  The underlying interval value seems right:

regression=# select '4 minutes'::interval - '5 minutes 30 seconds'::interval;?column?
------------00:01:30
(1 row)

so I think this is a to_char() bug.  Possibly it's platform-dependent
--- the roundoff behavior for division with a negative input varies
across machines.  However I do see the bug on HPUX 10.20 with CVS tip.

> Likewise,

> # select to_char('4 minutes'::interval -
> '4 minutes 30 seconds'::interval, 'mi:ss');

>   to_char
> ---------
>   00:-3
> (1 row)
        regards, tom lane