Re: Doubt on pg_timezone_names and pg_timezone_abbrevs

On Mon, Mar 31, 2025 at 8:39 PM Jayadevan M <maymala(dot)jayadevan(at)gmail(dot)com>
wrote:

> Hello PG members,
> I used 'IST' in a query like this - * (timestamp_hour) at time zone
> 'IST' time_ist *and did not get the expected output - timestamp in Indian
> Standard Time. So I queried the 2 views that provide timezone info and did
> not really understand the abbrev column.
> select name, abbrev, utc_offset from pg_timezone_names where abbrev =
> 'IST' ;
>

Since the S and T are non-location specific you get 26 different timezone
abbreviations to choose from. That wasn't enough for the world. So IST is
non-unique; and for historical reasons Ireland (Eire, which contains
Dublin) is given default priority.

> name | abbrev | utc_offset
> ---------------+--------+------------
> Eire | IST | 01:00:00
> Asia/Kolkata | IST | 05:30:00
> Asia/Calcutta | IST | 05:30:00
> Europe/Dublin | IST | 01:00:00
>

Suggest you adapt to using ISO names (the name column above) for timezones;
which are long enough and location-specific enough to be unique. In your
case, pick your preferred spelling of Calcutta I suppose.

There is a way to get a different interpretation for IST to be recognized
but I'd have to find it or wait for others to chime in.

David J.