Re: [HACKERS] Bug in to_timestamp().

On Mon, Jul 23, 2018 at 5:12 PM Arthur Zakirov <a.zakirov@postgrespro.ru> wrote:
> On Mon, Jul 23, 2018 at 04:30:43PM +0300, Arthur Zakirov wrote:
> > I looked for some tradeoffs of the patch. I think it could be parsing
> > strings like the following input strings:
> >
> > SELECT TO_TIMESTAMP('2011年5月1日', 'yyyy-MM-DD');
> > SELECT TO_TIMESTAMP('2011y5m1d', 'yyyy-MM-DD');
> >
> > HEAD extracts year, month and day from the string. But patched
> > to_timestamp() raises an error. Someone could rely on such behaviour.
> > The patch divides separator characters from letters and digits. And
> > '年' or 'y' are letters here. And so the format string doesn't match the
> > input string.
>
> Sorry, I forgot to mention that the patch can handle this by using
> different format string. You can execute:
>
> =# SELECT TO_TIMESTAMP('2011年5月1日', 'yyyy年MM月DD日');
>       to_timestamp
> ------------------------
>  2011-05-01 00:00:00+04
>
> =# SELECT TO_TIMESTAMP('2011y5m1d', 'yyyy"y"MM"m"DD"d"');
>       to_timestamp
> ------------------------
>  2011-05-01 00:00:00+04
>
> or:
>
> =# SELECT TO_TIMESTAMP('2011y5m1d', 'yyyytMMtDDt');
>       to_timestamp
> ------------------------
>  2011-05-01 00:00:00+04

Thank you, Arthur.  These examples shows downside of this patch, where
users may be faced with incompatibility.  But it's good that this
situation can be handled by altering format string.  I think these
examples should be added to the documentation and highlighted in
release notes.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company