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The surprising whimsy of the Time Zone Database

muddy.jprs.me

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Re: The surprising whimsy of the Time Zone Database

#11

Post by phantomathkg »

GauntletWizard wrote: post #8
skissane wrote: post #7

Earlier quoted context omitted.

> Give each country it's own NS in the TLD and give them the authority to update it There are 193 UN member states. Then add to that the Vatican, Taiwan, and dozens of overseas (or otherwise special) territories having ISO 3166 country codes. Can you trust all those governments to reliably play their part in such a system? This is part of why the current setup works - it isn’t dependent on the cooperation of any gove…

Who cares if it works in places that won't play nice? They're digging their own grave if they don't publish, and only hurting themselves. The nice thing about massively distributed systems is that they can be as reliable as the people who depend on them need them to be, with the relevant authorities having the option to be as real or as clowny as they want to be. That said, I would never respect the DNS TTL of such a…

You would care if you want to track the hostile countries local time.

Re: The surprising whimsy of the Time Zone Database

#12

Post by shagie »

GauntletWizard wrote: post #8
skissane wrote: post #7

Earlier quoted context omitted.

> Give each country it's own NS in the TLD and give them the authority to update it There are 193 UN member states. Then add to that the Vatican, Taiwan, and dozens of overseas (or otherwise special) territories having ISO 3166 country codes. Can you trust all those governments to reliably play their part in such a system? This is part of why the current setup works - it isn’t dependent on the cooperation of any gove…

Who cares if it works in places that won't play nice? They're digging their own grave if they don't publish, and only hurting themselves. The nice thing about massively distributed systems is that they can be as reliable as the people who depend on them need them to be, with the relevant authorities having the option to be as real or as clowny as they want to be. That said, I would never respect the DNS TTL of such a…

Who maintains what time it was in Yugoslavia in 1970? Or Serbia? What country maintains the time information for the island of Taiwan? Or Hong Kong while under British rule or while under Japanese rule?

It might be possible to use that for the information of now - to answer the question of "what is local time for me based on UTC?" or "what is local time for someone else now?" ... but what about the information of yesterday? When it was 12:01 PM in Chicago in 1948, what time was it in Hong Kong?

Re: The surprising whimsy of the Time Zone Database

#13

Post by vincent-manis »

wolrah wrote: post #9
themafia wrote: post #2

> the Time Zone Database also contains a surprising amount of whimsy. Which I would find "cute" if the database contained an equal amount of reason. I am perennially irritated that "US/Pacific" which is an _official_ name of a time zone _as used_ by the relevant time keeping authority, is called "backwards." I still think we should move away from a tz database, a 1970s idea, and move to a .timezone TLD with tzinfo st…

That might work for the current form of the country-specific time zones officially acknowledged by countries that exist in TLD form, but the tz database contains many more current time zones more importantly piles of historical time zones. Representing just the historical forms of currently recognized time zones in DNS would be a mess, without even getting in to those that are not associated with a country that curre…

There once was a country named Czechoslovakia.

Re: The surprising whimsy of the Time Zone Database

#15

Post by themafia »

shagie wrote: post #4
themafia wrote: post #2

> the Time Zone Database also contains a surprising amount of whimsy. Which I would find "cute" if the database contained an equal amount of reason. I am perennially irritated that "US/Pacific" which is an _official_ name of a time zone _as used_ by the relevant time keeping authority, is called "backwards." I still think we should move away from a tz database, a 1970s idea, and move to a .timezone TLD with tzinfo st…

That would provide the machine readable version... but not the human documentation of time. You wouldn't be able to debug the Moroccan Ramadan rule (which is provided as some elisp code) and its predictions for future changes. Having it be managed by governments would mean that the whim of a politician could break things by changing the established name... say from "US/Pacific" to "USA/Pacific" or deciding by fiat to…

> but not the human documentation of time.

And a single database maintained by a volunteer and accountable to no one is the best way to achieve this?

> say from "US/Pacific" to "USA/Pacific"

Did the US assign itself the .us TLD? These things are already defined. A more realistic example would be the US changing the name of the "Pacific" timezone to the "Western" timezone. All users of that timezone have to incorporate that change anyways and most would probably want to.

> change the timezone for a political enclave within another one that doesn't have a TLD.

You could actually grant the entire Navajo Nation the .nsn.us.timezone subdomain. I'm sure they find it absolutely insulting to be instructed to use "America/Denver." Why is that better? We could directly grant them their own authority.

There's also a handful of countries the tzdb didn't bother with and instruct to use their neighboring countries definition. In some instances this arrangement can be rather insulting to the political history of the two countries. Why is this better?

> the compromises in the design

What compromise? Here Eggert is ostensibly trying to get a sovereign government to participate in the "TZDB's requirements" and since he can't has to invent a hack to make things appear to work. Which is completely backwards and highlights precisely why I think this whole centralized database concept for this problem is flawed.

Re: The surprising whimsy of the Time Zone Database

#16

Post by themafia »

rendaw wrote: post #5
themafia wrote: post #2

> the Time Zone Database also contains a surprising amount of whimsy. Which I would find "cute" if the database contained an equal amount of reason. I am perennially irritated that "US/Pacific" which is an _official_ name of a time zone _as used_ by the relevant time keeping authority, is called "backwards." I still think we should move away from a tz database, a 1970s idea, and move to a .timezone TLD with tzinfo st…

You need historic timezone information to interpret past dates, not just the current timezones.

You need it to encode or decode past dates to unix time or other time standards. You do not need it to "interpret" past dates.

Even then the tzdb only covers _offsets_ within a day. So even without it you can get an answer that is very close to the "correct" answer. For dates at that great of a remove the lack of accuracy to a precise second is rarely a problem.

I don't exactly need to schedule a remote video phone call with someone still using Double British Summer War Time. For those that do have this requirement they can use whatever specialty database they want.

Combining these two concerns with insanely different scopes is precisely the issue with the tzdb.

Re: The surprising whimsy of the Time Zone Database

#18

Post by mulmen »

dfc wrote: post #6

If you like this there has been a interesting discussion on the tzdb mailing list about how to handle the Vancouver change and the next releases of the tzdb and the Unicode Common Locale Data Repository: https://lists.iana.org/hyperkitty/list/tz@iana.org/thread/IE...

Interesting to see mention of how quickly this was implemented. It seemed sudden to me but I wasn’t sure if I was just out of the loop.

Re: The surprising whimsy of the Time Zone Database

#19

Post by themafia »

MadnessASAP wrote: post #3
themafia wrote: post #2

> the Time Zone Database also contains a surprising amount of whimsy. Which I would find "cute" if the database contained an equal amount of reason. I am perennially irritated that "US/Pacific" which is an _official_ name of a time zone _as used_ by the relevant time keeping authority, is called "backwards." I still think we should move away from a tz database, a 1970s idea, and move to a .timezone TLD with tzinfo st…

> Which I would find "cute" if the database contained an equal amount of reason. I am perennially irritated that "US/Pacific" which is an _official_ name of a time zone _as used_ by the relevant time keeping authority, is called "backwards." This assumes that every point on earth has exactly 1 governing body and that a significant majority of the people agree on who that governing body is and that the governing body…

> Or that everyone in a region agrees on what time it is.

And how does the existence of the tzdb solve this problem in any way?

> Or that ccTLDs are sufficient to unambiguously cover the entire earths surface.

The user can still pick whatever they want. Just as they can now. The user can resolve ambiguity for themselves. Unless the tzdb decides unilaterally that their politically organized name for their timezone is somehow "wrong" and must be moved to the "backwards" file to be removed entirely. In which case they must accept whatever ambiguity the tzdb has created for them. "US/Pacific" is unambiguous. "America/Los_Angeles" is not.

> Your solution is insufficiently complex to solve a problem of this complexity.

You need to solve one problem. Publishing official tz information. If you have extended needs, then by all means, it's a computer, do whatever you like, but for the overwhelming majority of the population of earth, they need one function.

"What time does my government think it is because that time controls when things open, when I'm late for work, and when official paperwork has to be filed."

If you want a "whimsical" database that correctly gets timezones right for certain Japanese islands during the war, then you have that, but honestly, what general use case is there for this?

Re: The surprising whimsy of the Time Zone Database

#20

Post by fzeindl »

I once digged into this database out of curiosity and found incredibly detailed research on many edge cases. Like time zones in Germany being temporarily aligned to Moscow during soviet occupancy after World War Two.

One particular commenter stood out to me, so I looked him up because I was interested which kind of people spend so much time correcting timezone information.

Turns out he was an astrologer and wanted his astrology-program to work perfectly correct.

I find it funny that we have to thank astrology for the correct calculations in our banking software :).

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