The date / time of your message at the top of my email client was: Thu, 03 Jul 2003 13:18:09 -0400
And most of my stuff is -0600 or -0700 and I live in Colorado. Every instance I've seen that shows the correction for me has been a -0600/-0700 depending on daylight savings. So, it looks like the standard for email / system time. I use timestamptz On Thu, 3 Jul 2003, Tom Lane wrote: > Currently, the extract(timezone_hour ...) and extract(timezone_minute > ...) constructs (also the equivalent date_part() calls) return positive > values for timezones west of Greenwich, and negative values for > timezones east of Greenwich. > > While the SQL92 spec was quite vague on the subject of the signs of > timezone displacements, SQL99 seems to be pretty clear that > > Local time is equal to UTC (Coordinated Universal Time) plus > the time zone displacement, > > which would mean that positive displacements correspond to zones east of > Greenwich. Another point in favor of this interpretation is that the > spec defines the legal range of displacement as -12:59 to +13:00, which > is clearly intended to accommodate New Zealand Daylight Time (13 hours > ahead of UTC) ... so NZDT has to be a positive offset not a negative one. > > Interestingly, this is also the sign convention used by the timestamptz > and timetz I/O routines, which are certainly much more heavily used than > EXTRACT(). The only other place I can find that uses west-is-positive > convention is the code for SET TIMEZONE with a direct numeric timezone > offset. > > I think we got this wrong as a result of misreading SQL92, and we ought > to change EXTRACT() and SET/SHOW TIMEZONE to use the same sign > convention as timestamp input/display use. > > Comments? Can anyone confirm which sign is used by other DBMSes? > > regards, tom lane > > ---------------------------(end of broadcast)--------------------------- > TIP 9: the planner will ignore your desire to choose an index scan if your > joining column's datatypes do not match > ---------------------------(end of broadcast)--------------------------- TIP 8: explain analyze is your friend