Re: roundoff problem in time datatype

On Mon, 26 Sep 2005, Tom Lane wrote:

> > Actually, I think there is a case where 24:00 is a proper time. Isn't
> > it used for adding leap seconds ?
>
> No, I think the usual notation for a leap-second is '23:59:60'.
> We do allow 60 in the seconds field for this purpose.

Yes, and it can go up to 23:59:60.999999 (depending on how many fractional
seconds one want).

> I suppose there's another possible approach, which is to special-case
> the output of this value to look like '23:59:60' instead of '24:00:00'.

You would get the same problem with 23:59:60.9 which I guess you want to
round up.

One "solution" is to round '23:59:59.9'::time(0) up to '00:00:00'. That is
normally the next following time value after all. I know why you might not
want to round it "up" to 00:00:00, but it's one logical solution.

By the way, here is another example of the same problem:

# SELECT time '23:59:59.9' + interval '0.1';
?column?
----------
24:00:00

# SELECT time '23:59:59.9' + interval '0.11';
?column?
-------------
00:00:00.01
(1 rad)

--
/Dennis Björklund