On 10/05/2018 15:31, Lester Caine wrote: > On 10/05/18 18:47, Adriano dos Santos Fernandes wrote: >> 99.9% of our users will use the "official" database. > > And therefore will have no idea just which "official" database they > are using. This is just carrying on the current mess that is inherent > when one has no idea just which rules WERE USED to create the data. I > became involved with the TZ list because a large block of genealogical > data I was using was giving conflicting offsets. Over time the > historic rules have been change in much the same way the current rules > are change. North Korea has just added a rule change but it has still > to filter through all the "official" databases so we are all using the > new rule, but one needs to know that the UTC time logged two weeks ago > for the meeting next week HAS changed! The VERSION of the rule set > being used is just as important as the timezone and in a database with > many years of data the rules WILL be changing so one needs to know > just WHICH rule was applied when the data was stored against now. The > material I was working with was essentially trash as no one had > recorded the version of TZ that was being used, and as different > computer OS's used different version of TZ the whole thing became a mess. > > Today the CORRECT identification of a timezone rule set is 'tz > ident/version' and recording anything less is just a gamble on what > you get. > > I can give more examples of problems which NOT knowing which rule set > was used to create the 'international' timetable when local DST times > are changed at short notice ... TZDist is intended to prevent this > problem, but since there are no active sources we are still stuck with > the miss-match of data between different OS's and system. > if you want to work with fixed rules even when they change, you should have specialized treatment of the data. It's not difficult.
Store your data using the displacement syntax +/- HH:MM and add the region name to another column. No other database engine is maintaining various versions at the same time. Fortunately. Adriano ------------------------------------------------------------------------------ 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
