Hi ,
What is the right approach for using AT TIME ZONE function?
Option 1: <some_date with tz> AT TIME ZONE 'IST'
Option 2: <some_date with tz> AT TIME ZONE 'Asia/Kolkata'
In the first option, I get +2:00:00 offset (when timezone_abbrevations = 'Default') and for option 2 , +5:30 offset.
I can see multiple entries for IST in pg_timezone_names with different utc_offset, but in pg_timezone_abbrev there is one entry. I guess AT TIME ZONE function using the offset shown in pg_timezone_abbrev.
ovdb=> select * from pg_timezone_names where abbrev = 'IST';
name | abbrev | utc_offset | is_dst
---------------------+--------+------------+--------
Asia/Calcutta | IST | 05:30:00 | f
Asia/Kolkata | IST | 05:30:00 | f
Europe/Dublin | IST | 01:00:00 | t
posix/Asia/Calcutta | IST | 05:30:00 | f
posix/Asia/Kolkata | IST | 05:30:00 | f
posix/Europe/Dublin | IST | 01:00:00 | t
posix/Eire | IST | 01:00:00 | t
Eire | IST | 01:00:00 | t
ovdb=> select * from pg_timezone_abbrevs where abbrev = 'IST';
abbrev | utc_offset | is_dst
--------+------------+--------
IST | 02:00:00 | f
In my system, we receive TZ in abbrev format (3 character, like EST, PST ...).
I have tried changing the timezone_abbrevations = 'India', then it worked fine (IST is giving +5:30 offset)
So,
What is recommended, use name instead of abbrev in TZ conversion function?
Or
Change the timezone_abbrevations to 'India'?
Regards,