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

"Kevin Grittner" <Kevin(dot)Grittner(at)wicourts(dot)gov> writes:
> "Jonathan Brinkman" <JB(at)BlackSkyTech(dot)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