Thread: timezone offsets and documentation

The documentation says the time with time zone datatype allows zone
offsets from +12 to -12.

http://www.postgresql.org/docs/8.0/static/datatype-datetime.html

This is at odds with the implementation which allows values +1359 to -1359

jurka=# select '00:00:00+1359'::timetz;
     timetz
----------------
 00:00:00+13:59
(1 row)


Further the list of available timezone names says that Etc/GMT-14 is a
valid timezone.

http://www.postgresql.org/docs/8.0/static/datetime-keywords.html#DATETIME-TIMEZONE-SET-TABLE

This allows:

jurka=# set timezone to 'Etc/GMT-14';
SET
jurka=# select '00:00:00'::timetz;
   timetz
-------------
 00:00:00+14
(1 row)

but this is not an allowed value:

jurka=# select '00:00:00+14'::timetz;
ERROR:  time zone displacement out of range: "00:00:00+14"


Kris Jurka

Kris Jurka <books@ejurka.com> writes:
> The documentation says the time with time zone datatype allows zone
> offsets from +12 to -12.

I see noplace that opines on this at all ...

            regards, tom lane

On Sun, 6 Feb 2005, Tom Lane wrote:

> Kris Jurka <books@ejurka.com> writes:
> > The documentation says the time with time zone datatype allows zone
> > offsets from +12 to -12.
>
> I see noplace that opines on this at all ...
>

http://www.postgresql.org/docs/8.0/static/datatype-datetime.html

The reference I provided shows Table 8-9 Date/Time Types:

time [ (p) ] with time zone    12 bytes    times of day only, with
time zone    00:00:00.00+12    23:59:59.99-12    1 microsecond / 14 digits

The low value/high value columns seem to me to indicate the +/-12 zone
offset range.

Kris Jurka

Quite some time ago, Kris Jurka <books@ejurka.com> wrote:
> This allows:

> jurka=# set timezone to 'Etc/GMT-14';
> SET
> jurka=# select '00:00:00'::timetz;
>    timetz
> -------------
>  00:00:00+14
> (1 row)

> but this is not an allowed value:

> jurka=# select '00:00:00+14'::timetz;
> ERROR:  time zone displacement out of range: "00:00:00+14"

Yeah.  It's worse than that actually, because we will take something
like

SET TIMEZONE TO 'Etc/GMT+15';

I haven't traced through the code but I bet this is being accepted by
the "POSIX zone name" rule.  Perhaps we should sanity-check the computed
offset?

I'm not sure what the use of GMT-14 is, but I suggest that we ought to
defer to the judgment of the zic people in making it available.
Accordingly, we probably ought to modify the range of allowed timezone
offsets to allow -14:00 (and maybe +14:00 as well?)

Comments?

            regards, tom lane