Обсуждение: BUG #16472: Bug in to_timestamp ?

The following bug has been logged on the website:

Bug reference:      16472
Logged by:          jesvh
Email address:      jesvh.cht@gmail.com
PostgreSQL version: Unsupported/Unknown
Operating system:   windows 10
Description:

Hi :
I execute a update SQL as below :
update Table1 set date1=to_timestamp('19790701000000', 'YYYYMMDDHH24MISS')
where .....

date1 is a timestamp type column, the result in DB is  1979-07-01 01:00:00
where come from that '01' hour ?

but if set to other date value, it works correct ....
Is it a special bug ?

Hi!

On Mon, Jun 1, 2020 at 1:38 PM PG Bug reporting form
<noreply@postgresql.org> wrote:
> Hi :
> I execute a update SQL as below :
> update Table1 set date1=to_timestamp('19790701000000', 'YYYYMMDDHH24MISS')
> where .....
>
> date1 is a timestamp type column, the result in DB is  1979-07-01 01:00:00
> where come from that '01' hour ?
>
> but if set to other date value, it works correct ....
> Is it a special bug ?

It's likely related to clock shift in your timezone.

What is your timezone and PostgreSQL version?  You can figure out them
using following queries.
show timezone;
select version();

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

Alexander Korotkov <a.korotkov@postgrespro.ru> writes:
> On Mon, Jun 1, 2020 at 1:38 PM PG Bug reporting form
> <noreply@postgresql.org> wrote:
>> I execute a update SQL as below :
>> update Table1 set date1=to_timestamp('19790701000000', 'YYYYMMDDHH24MISS')
>> where .....
>> date1 is a timestamp type column, the result in DB is  1979-07-01 01:00:00
>> where come from that '01' hour ?

> It's likely related to clock shift in your timezone.

July 1 would be an odd time for a seasonal DST shift ... but quickly
thumbing through the tzdata files, I see one for Asia/Taipei on that date
in 1979.  So I guess that the OP is using that zone, and the answer to the
question is "midnight of that date did not exist in Taiwan; their clocks
shifted forward from 23:59:59 to 01:00:00".

            regards, tom lane