Re: TO_CHAR(timestamptz,datetimeformat) wrong after DST change

To make this even weirder, this effect only seems to happen to the
'postgres' user. When I use the 'bucardo' user, the time zone is correct!

postgres@Cloud-DB1:~$ psql beta_cms_main -c "select now();"
              now
-------------------------------
 2011-03-21 08:22:37.521213-05
(1 row)

postgres@Cloud-DB1:~$ psql beta_cms_main -c "SHOW TIME ZONE;"
 TimeZone
----------
 EST
(1 row)

postgres@Cloud-DB1:~$ su - bucardo
Password:
bucardo@Cloud-DB1:~$ psql beta_cms_main -c "SHOW TIME ZONE;"
     TimeZone
------------------
 America/New_York
(1 row)

bucardo@Cloud-DB1:~$ psql beta_cms_main -c "select now();"
              now
-------------------------------
 2011-03-21 09:23:03.079692-04
(1 row)

bucardo@Cloud-DB1:~$ logout
postgres@Cloud-DB1:~$ psql beta_cms_main -c "SHOW TIME ZONE;"
 TimeZone
----------
 EST
(1 row)

-----Original Message-----
From: Jonathan Brinkman [mailto:JB@BlackSkyTech.com]
Sent: Monday, March 21, 2011 9:14 AM
To: 'Tom Lane'; 'Kevin Grittner'
Cc: 'pgsql-bugs@postgresql.org'
Subject: RE: [BUGS] TO_CHAR(timestamptz,datetimeformat) wrong after DST
change

I understand now that I must use America/New_York for DST to function.  I
see in select * from pg_timezone_names ; that 'EDT' is a shortcut. I tried
to SET TIME ZONE 'EDT'; but PG doesn't seem to like that.

My problem is that the corrected time zone (America/New_York) doesn't seem
to stick after updating. I update it in psql (cmd line) and within psql it
returns correctly. But when I then view now() from command line the DST
change is not there and time zone is again 'EST'. So:

postgres@Cloud-DB1:~$ psql beta_cms_main -c "SHOW TIME ZONE;"
 TimeZone
----------
 EST
(1 row)

postgres@Cloud-DB1:~$ psql beta_cms_main
psql (8.4.7)
Type "help" for help.

beta_cms_main=# show time zone;
 TimeZone
----------
 EST
(1 row)

beta_cms_main=# set time zone 'America/New_York';
SET
beta_cms_main=# show time zone;
     TimeZone
------------------
 America/New_York
(1 row)

beta_cms_main=# \q

postgres@Cloud-DB1:~$ psql beta_cms_main -c "SHOW TIME ZONE;"
 TimeZone
----------
 EST
(1 row)

postgres@Cloud-DB1:~$ psql beta_cms_main -c "select now();"
              now
-------------------------------
 2011-03-21 08:09:07.029884-05
(1 row)

[INCORRECT, SHOULD BE -04 and it is now 9:09AM, not 8:09AM]

I enabled America/New_York in postgresql.conf and restarted PG but no
change.
I re-ran tzdata in Ubuntu but no change.
I rebooted the server no change.







-----Original Message-----
From: Tom Lane [mailto:tgl@sss.pgh.pa.us]
Sent: Friday, March 18, 2011 12:47 PM
To: Kevin Grittner
Cc: JB@BlackSkyTech.com; pgsql-bugs@postgresql.org
Subject: Re: [BUGS] TO_CHAR(timestamptz,datetimeformat) wrong after DST
change

"Kevin Grittner" <Kevin.Grittner@wicourts.gov> writes:
> "Jonathan Brinkman" <JB@BlackSkyTech.com> wrote:
>> I guess EST is not DST-friendly?

> EST stands for Eastern *Standard* Time, which is explicitly *not*
> under Daylight Saving Time.

Right.  SET TIMEZONE 'EST' gets you GMT-5 all year round.
For background see this bit in src/timezone/data/northamerica:

# From Arthur David Olson, 2005-12-19
# We generate the files specified below to guard against old files with
# obsolete information being left in the time zone binary directory.
# We limit the list to names that have appeared in previous versions of
# this time zone package.
# We do these as separate Zones rather than as Links to avoid problems if
# a particular place changes whether it observes DST.
# We put these specifications here in the northamerica file both to
# increase the chances that they'll actually get compiled and to
# avoid the need to duplicate the US rules in another file.

# Zone    NAME        GMTOFF    RULES    FORMAT    [UNTIL]
Zone    EST         -5:00    -    EST
Zone    MST         -7:00    -    MST
Zone    HST        -10:00    -    HST
Zone    EST5EDT         -5:00    US    E%sT
Zone    CST6CDT         -6:00    US    C%sT
Zone    MST7MDT         -7:00    US    M%sT
Zone    PST8PDT         -8:00    US    P%sT

(Note: the lack of a RULES entry means no DST rule.)

            regards, tom lane