Re: Postgres and timezones

2016-01-20 14:24 GMT+01:00 Steve Rogerson <steve(dot)pg(at)yewtc(dot)demon(dot)co(dot)uk>:

> On 20/01/16 12:53, Albe Laurenz wrote:
> > Steve Rogerson wrote:
> >> Hi, this is wrong:
> >>
> >> # select to_char('2016-01-20 00:00'::timestamp at time zone
> 'Europe/Lisbon',
> >> 'TZ');
> >> to_char
> >> ---------
> >> GMT
> >> (1 row)
> >>
> >>
> >> It should be WET, "Western European Time". Is there something I'm doing
> wrong?
> >
> > That query will always give you your local timezone.
> >
> > Here in Austria I get:
> > us
> > test=> select to_char('2016-01-20 00:00'::timestamp at time zone
> 'Asia/Yerevan', 'TZ');
> > ┌─────────┐
> > │ to_char │
> > ├─────────┤
> > │ CET │
> > └─────────┘
> > (1 row)
> >
> > Yours,
> > Laurenz Albe
> >
> That seems odd, but never mind. I'll ask the direct qn then given the
> above is
> it possible to determine the short TZ, say WET in my example.
>
> Thinking about it, probably not as I suspect that pg only stores the
> offset in
> seconds(?) from UTC, so once it has parsed "2016-.... 'Europe/Lisbon'" it
> has
> lost track of the origin TZ and in that case what else could "to_char( ...,
> 'TZ') mean then other than the current client TZ.
>

Postgres doesn't store original TZ. It does recalculation to local TZ. If
you need original TZ, you have to store it separetely.

Regards

Pavel

>
> Steve
>
>
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