Re: Urgent PST time changing tonight

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