

Samoa cancels Friday 30th and travels one day forward in time - tjriley82
http://www.nytimes.com/2011/12/30/world/asia/samoa-to-skip-friday-and-switch-time-zones.html

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qntm
It's actually quite lucky that the world has a sensible longitude upon which
an International Date Line can be dropped. Imagine if there was an unbroken
ring of industrialised nations going all the way around the Earth, I can see a
situation where each nation wants to do business with the nation to its
immediate west so badly that they just adjust their clocks forward and forward
over the course of decades. Eventually, every nation on Earth has done it, and
an entire day has essentially disappeared from the calendar - except that the
UK is at UTC+24:00 now.

~~~
dkasper
Perhaps we would have a different notation of time if this were the case.

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rmc
It's cases like this that show that you should use a proper timezone library
in your code. Too often I see websites where the timezone field is given as
"+/- X from GMT". Just store everything in UTC, and use tzdata fields (e.g.
"Europe/London") to convert to something nice to show the user, and People
Cleverer Than You™ will make sure everything works.

~~~
grimlck
Storing everything in UTC is a huge improvement, but is still an imperfect
solution because the Tz database changes over time.

Suppose you are writing a appointment tracking system, and, at some point
before the olson tz database has been updated with this change, the user in
the Samoa timezone creates an future appointment for Jun 2, 2012. That would
be stored in UTC.

Now, you upgrade the olson TZ database file on your server to a newer version,
which incorporates the Somoa tz change. Now, without any user input, the
appointment is suddenly on Jun 3, 2012! (because the same UTC date, with the
updated TZ database, is Jun 3, 2012)

Is that what a user would have expected if they created the appointment for
Jun 2, 2012? I would say no. But that said, what if the appointment was for
Dec 30 2011? That date no longer exists, so it would have be pushed ahead
automatically.

Conclusion: time zones are hard

~~~
natrius
My assumption was that the TZ database noted when changes in time zones
happened so there was always an accurate one-to-one mapping between a Unix
time and a time in each time zone. Adding 2012's time zone information
wouldn't override 2010's. Is this incorrect?

~~~
rmc
> there was always an accurate one-to-one mapping between a Unix time and a
> time in each time zone

That's not true in general. When the "clocks go backwards", there are two
1:30ams on that morning.

The bug this comment is refering to, is where you convert from local to UTC as
soon as the user enters the datetime, and then use that from then on. Since
the "local to UTC" conversion might change between now and the date, as the
tzdata time is updated, you might get this bug.

~~~
mikeash
It seems to me that it's impossible to solve this bug in the general case. If
the user enters March 15, 2012 before the switch, should that become March 16,
2012 after the switch, or stay March 15? Either scenario could be correct
depending on the intent of the date. Messy.

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redthrowaway
Who decided to cancel _Friday_? Surely there would have been greater agreement
for cancelling Monday.

~~~
marquis
Then tuesday is the new monday.. you can't escape it. Also, easier to cope
with changes over the weekend for those doing international business.

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tlholaday
I was pleased that the author, Seth Mydans described January 1, 2000 as "what
was called the new millennium."

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technomancy
I love it when the news prompts flashbacks to Umberto Eco.

<http://en.m.wikipedia.org/wiki/The_Island_of_the_Day_Before>

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ars
I'm quite curious if local churches will follow along with the change.

I know Jews wouldn't, and I doubt Muslims would, but I don't think there are
any Jews there anyway, not sure about Muslims.

~~~
jonknee
Why not? It's arbitrary anyways--as the article mentions the same place
previously switched (which means if the Jews didn't like change they would
still be on the time that everyone is now switching back to).

~~~
ars
The Jewish religion has it's own date line that does not correspond to the
international one.

My question was what does Christianity do, and I guess no one here knows.

~~~
protomyth
Christianity is actually split on which day to keep. Those that follow the
Catholic Church (via canon 29 of the Council of Laodicea) worship on Lord's
Day[1] (Sunday). Those that feel the church could not change the day of
worship (e.g. Seventh Day Baptists) worship on the Sabbath (Saturday).

Wikipedia has a small breakdown for the 7th day in
<http://en.wikipedia.org/wiki/Sabbath> \- some going with local, some going
with time in Israel. Not being Jewish, I am not sure how accurate this one is
for Jews: <http://www.star-k.org/kashrus/kk-trav-dateline.htm>

It was my understanding that Catholics go with local to determine Sunday.

[1] <http://en.wikipedia.org/wiki/Lord%27s_Day>

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finnw
Another version of the story for non-NYT subscribers:

<http://www.bbc.co.uk/news/world-asia-16351377>

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AngryParsley
The change in timezone data exposed a bug in pytz:
<https://bugs.launchpad.net/pytz/+bug/885163>

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jorisw
I would not want to be a calendar software developer right now.

~~~
jonknee
Why not? It's a simple timezone change. Moreover, it's a timezone change that
effects a very small number of people.

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languagehacker
Samoa will do anything to make it easier to trade with Australia, including
switching what side of the road drivers should use. It's getting a little
ridiculous.

~~~
marquis
Samoans mostly live and work in/with Australia and New Zealand. Doesn't that
make more sense, than pretending they are closer to the U.S.?

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malvim
Here's hoping no samoans have their birthdays on December 30th. It would sure
suck if my government cancelled the entire day of my birthday!

------
Pelayo
And they become the first to celebrate the new year on the last new year there
will ever be.

