On Thu, Nov 10, 2016 at 10:52 AM, Jon Zeppieri <zeppi...@gmail.com> wrote:
> > > On Thu, Nov 10, 2016 at 10:45 AM, Jon Zeppieri <zeppi...@gmail.com> wrote: > >> >> >> On Thu, Nov 10, 2016 at 4:52 AM, George Neuner <gneun...@comcast.net> >> wrote: >> >>> >>> On 11/9/2016 2:18 AM, Ryan Culpepper wrote: >> >> >> >>> >>> Postgresql follows the ISO convention because the SQL standard follow >>> the ISO convention. Ask Postgresql for "+5" ... note I dropped the >>> separator and minutes (more below) ... and you will get back time in Mumbai >>> India. However, Postgresql has to interoperate with the opposing standard >>> TZ database, so if you ask for "EST" you will get the time for New York >>> City because Postgresql negated the offset. >>> >> >> I thought Postgres used the same convention as IANA, but it's been a >> while. >> >> > Ah, I see what's going on here. Right, so the tz database has certain time > zone names like: > > Etc/GMT-4 > > Where the *name itself* follows the POSIX convention, though it maps to an > offset that follows the ISO/Olson convention. You can see this if you look > at the source file "etcetera" in the tz database. You'll see lines like > this: > > Zone Etc/GMT-14 14 - +14 > Zone Etc/GMT-13 13 - +13 > Zone Etc/GMT-12 12 - +12 > Zone Etc/GMT-11 11 - +11 > > You can see that the time zone named Etc/GMT-14 maps to a single offset of > UTC+14. No joke. > > By the way, these time zones exist specifically *for* POSIX compatibility; that's why their names follow the POSIX convention. It's not that the tz database adopted the POSIX convention in general. Basically: don't use these time zones unless you have a very good reason to. Or ones like "EST." Stick to the ones that follow the continent_ish/city naming convention. - Jon -- You received this message because you are subscribed to the Google Groups "Racket Users" group. To unsubscribe from this group and stop receiving emails from it, send an email to racket-users+unsubscr...@googlegroups.com. For more options, visit https://groups.google.com/d/optout.
