postgres default timezone

To acomplish the timezone change in Postgres 9.1 you must:

1.- Search in your "timezones" folder in /usr/share/postgresql/9.1/ for the appropiate file, in my case would be "America.txt", in it, search for the closest location to your zone and copy the first letters in the left column.

For example: if you are in "New York" or "Panama" it would be "EST":

#  - EST: Eastern Standard Time (Australia)
EST    -18000    # Eastern Standard Time (America)
                 #     (America/New_York)
                 #     (America/Panama)

2.- Uncomment the "timezone" line in your postgresql.conf file and put your timezone as shown:

#intervalstyle = 'postgres'
#timezone = '(defaults to server environment setting)'
timezone = 'EST'
#timezone_abbreviations = 'EST'     # Select the set of available time zone
                                        # abbreviations.  Currently, there are
                                        #   Default
                                        #   Australia

3.- Restart Postgres

Choose a timezone from:

SELECT * FROM pg_timezone_names;

And set as below given example:

ALTER DATABASE postgres SET timezone TO 'Europe/Berlin';

Use your DB name in place of postgres in above statement.

The time zone is a session parameter. So, you can change the timezone for the current session.

See the doc.

set timezone TO 'GMT';

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Or, more closely following the SQL standard, use the SET TIME ZONE command. Notice two words for "TIME ZONE" where the code above uses a single word "timezone".

SET TIME ZONE 'UTC';

The doc explains the difference:

SET TIME ZONE extends syntax defined in the SQL standard. The standard allows only numeric time zone offsets while PostgreSQL allows more flexible time-zone specifications. All other SET features are PostgreSQL extensions.