Re: [HACKERS] Bug in to_timestamp().

On Wed, Sep 19, 2018 at 2:57 PM Alexander Korotkov
<a.korotkov@postgrespro.ru> wrote:
>
> On Tue, Sep 18, 2018 at 4:42 PM Alexander Korotkov
> <a.korotkov@postgrespro.ru> wrote:
> > But, I found related issue in cf9846724.  Before it was:
> >
> > # select to_timestamp('2018 01 01', 'YYYY9MM9DD');
> >       to_timestamp
> > ------------------------
> >  2018-01-01 00:00:00+03
> > (1 row)
> >
> > But after it becomes so.
> >
> > # select to_timestamp('2018 01 01', 'YYYY9MM9DD');
> > ERROR:  invalid value "1 " for "MM"
> > DETAIL:  Field requires 2 characters, but only 1 could be parsed.
> > HINT:  If your source string is not fixed-width, try using the "FM" modifier.
> >
> > That happens because we've already skipped space "for free", and then
> > NODE_TYPE_CHAR eats digit.  I've checked that Oracle doesn't allow
> > random charaters/digits to appear in format string.
> >
> > select to_timestamp('2018 01 01', 'YYYY9MM9DD') from dual
> > ORA-01821: date format not recognized
> >
> > So, Oracle compatibility isn't argument here. Therefore I'm going to
> > propose following fix for that: let NODE_TYPE_CHAR eat characters only
> > if we didn't skip input string characters more than it was in format
> > string.  I'm sorry for vague explanation.  I'll come up with patch
> > later, and it should be clear then.
>
> Please find attached patch for fixing this issue.  It makes handling
> of format string text characters be similar to pre cf984672 behavior.
> See the examples in regression tests and explanation in the commit
> message.  I'm going to commit this if no objections.
>

With this patch, to_date and to_timestamp behaving differently, see this:

edb=# SELECT to_date('18 12 2011', 'xDDxMMxYYYY');
      to_date
--------------------
 18-DEC-11 00:00:00
(1 row)

edb=# SELECT to_timestamp('18 12 2011', 'xDDxMMxYYYY');
       to_timestamp
---------------------------
 08-DEC-11 00:00:00 -05:00      <=========== Incorrect output.
(1 row)

Regards,
Amul