On 14/12/17 21:39, Adriano dos Santos Fernandes wrote: >>> This year our politics was speculating to not start DST just days before the >>> initial date. Given the the number of changes to DST and simple offsets is very small, then the occurrence of problems is rare, and on the whole only affects events that do cross multiple timezones, although it has been known for events to have 'moved' time wise while participants have been flying to an event. Since short term changes affect many areas, governments do seem to be getting a little more organised, but there is nothing stopping some new administration changing an offset or DST rule within days of the event.
>> Let's discuss that example further. >> >> So, what do you expect the impact of the change to the DST would be for an >> applications. >> >> - You (in BrasÃlia) setup a phone call/meeting, 6 months ago, for today at >> 7am (Dec 12, 2017 == UTC -2) with customers in Mumbai (5:30pm -- UTC +5:30) >> and Adelaide Australia ( 10:30pm -- UTC +10:30) > 7am in UTC -2 => 9am in UTC+0 > 9am in UTC+0 => 2:30pm in UTC+5:30 > 9am in UTC+0 => 7:30pm in UTC+10:30 > Am I making a mistake or you? In my book YES ... because you don't know from that 'data' if any offset changes should the event need to be moved. The problem I had in the past was with meetings being moved over a DST boundary. And this was in a SINGLE timezone. The software was normalizing everything to UTC time, so that it could be displayed in local time of the client, but what was forgotten in the software was which timezone was used to store the data. It was JUST stored as an offset, so when the meeting moved the change in DST was missed. The fact that some timezones have DST changes and some do not means that one needs to store the the actual rule used and not just an offset. But more than that, one HAS to remember the version of the rule being used! So rather than simply adding an offset value to a datetime stamp and calling it 'time-zoned', one needs to properly manage the timezone information and store the identity of the information used to create the offset! Anything else should not be called 'time-zoned' ... -- Lester Caine - G8HFL ----------------------------- Contact - http://lsces.co.uk/wiki/?page=contact L.S.Caine Electronic Services - http://lsces.co.uk EnquirySolve - http://enquirysolve.com/ Model Engineers Digital Workshop - http://medw.co.uk Rainbow Digital Media - http://rainbowdigitalmedia.co.uk ------------------------------------------------------------------------------ Check out the vibrant tech community on one of the world's most engaging tech sites, Slashdot.org! http://sdm.link/slashdot Firebird-Devel mailing list, web interface at https://lists.sourceforge.net/lists/listinfo/firebird-devel
