Thanks Steve for sharing this info. Thanks Deepak On Mon, Mar 9, 2009 at 12:14 PM, Steve Crawford < scrawf...@pinpointresearch.com> wrote:
> DM wrote: > >> Hi All, >> >> PST time changing tonight, I am not sure if this is going to affect the >> database.... >> > IF you are up-to-date on your TZ files the database itself should be fine. > But external processing is another matter - especially if you have processes > that assume conventions from previous PG versions. For example: > > PG 7.4 (one day = 24 hours): > select now(); > > now > ------------------------------- > 2009-03-09 12:05:42.533139-07 > > select now()-'2 days'::interval; > ?column? > ------------------------------- > 2009-03-07 11:05:43.963526-08 > > > But in 8.3 (day interval is DST aware): > select now(); > > now > ------------------------------- > 2009-03-09 12:04:21.813654-07 > > select now()-'2 days'::interval; > ?column? > ------------------------------- > 2009-03-07 12:04:47.693384-08 > > That's just in the database itself and without cross-country processing > (i.e.: if you have somewhat synchronized processes that assume that New York > is 3 hours ahead of San Francisco you can have problems if you don't > consider that New York changed to DST 3 hours ahead of San Francisco). > > Then there are the scripts that calculate dates externally for feeding into > your database-backed processes (for fun, try "-d yesterday" and "-d > tomorrow" in most versions of the "date" command in the vicinity of DST > changes). > > Cheers, > Steve > >
