Re: BUG #6385: extract epoch at timezone returns wrong value - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #6385: extract epoch at timezone returns wrong value
Date
Msg-id 5519.1326039558@sss.pgh.pa.us
Whole thread Raw
In response to BUG #6385: extract epoch at timezone returns wrong value  (sreeraj@ordyn.com)
List pgsql-bugs
sreeraj@ordyn.com writes:
> When I give "SELECT extract(epoch from now() );" the output is
> 1325872658.xxx

> I would expect a slightly incremented value when after a few seconds I give
> the command "SELECT extract(epoch from now() at time zone 'utc+05:30');" .
> Nut I get the value 1325833067.xxx which is the value for utc-05:30 !!!

> And when I give "SELECT extract(epoch from now() at time zone
> 'utc-05:30');", I get 1325872672.xxx which is what is expected if I
> specified timezone +05:30 !!!

I think you are confused about the sign convention for time zones
specified in POSIX notation.  See
http://www.postgresql.org/docs/9.1/static/datatype-datetime.html#DATATYPE-TIMEZONES
particularly this comment:

    Another issue to keep in mind is that in POSIX time zone names,
    positive offsets are used for locations west of
    Greenwich.  Everywhere else, PostgreSQL follows the ISO-8601
    convention that positive timezone offsets are east of Greenwich.

This is not a bug, or at least not our bug --- we're just doing the best
we can to cope with inconsistent standards documents.

            regards, tom lane

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