News for the tz database

#1

Post by Sir_Cmpwn » Fri, Jul 27, 2018, 8:38 PM UTC

News for the tz database
github.com

Re: News for the tz database

#2

Post by mikestaszel » Sat, Jul 28, 2018, 2:00 PM UTC

Amazing work I take for granted. Thank you to all the maintainers and contributors!

Re: News for the tz database

#3

Post by simonw » Sat, Jul 28, 2018, 2:02 PM UTC

One of my favorite surprising corners of the internet is the tz mailing list, where updates to the tz database are actively discussed:

https://mm.icann.org/pipermail/tz/2018-July/thread.html

The amount of effort and detail that goes into this database is astonishing - every few days there's a new twist introduced by timezone legislation somewhere around the world.

Even more impressive is their dedication to building a correct database of historic timezone changes - here's a post where someone submitted further details on the history of time in Macau for example: https://mm.icann.org/pipermail/tz/2018-May/026467.html

Re: News for the tz database

#4

Post by jessaustin » Sat, Jul 28, 2018, 2:11 PM UTC

It isn't clear why Ireland would need a negative DST? Don't they also "spring forward and fall back"?

Re: News for the tz database

#5

Post by teddyh » Sat, Jul 28, 2018, 2:18 PM UTC

Does every Docker container, snap, flatpack etc. need to be updated every time the tz database releases a new update? Do they?

Re: News for the tz database

#6

Post by x1798DE » Sat, Jul 28, 2018, 2:20 PM UTC

jessaustin wrote: post #4

It isn't clear why Ireland would need a negative DST? Don't they also "spring forward and fall back"?

In the Summer they call their time "Irish Standard Time", which indicates that they view the summer offset as the standard one and they are using "winter time" [1]. It's just a matter of perspective.

[1] https://en.wikipedia.org/wiki/Winter_time_(clock_lag)

Re: News for the tz database

#7

Post by jwilk » Sat, Jul 28, 2018, 2:57 PM UTC

You linked to a copy embedded in pytz.

Upstream database is here:

https://github.com/eggert/tz

Re: News for the tz database

#8

Post by sctb » Sat, Jul 28, 2018, 3:10 PM UTC

jwilk wrote: post #7

You linked to a copy embedded in pytz. Upstream database is here: https://github.com/eggert/tz

Thanks, we've updated the link from https://github.com/stub42/pytz/blob/master/tz/NEWS.

Re: News for the tz database

#9

Post by klodolph » Sat, Jul 28, 2018, 3:12 PM UTC

teddyh wrote: post #5

Does every Docker container, snap, flatpack etc. need to be updated every time the tz database releases a new update? Do they?

It is not necessary. Various backend systems can store dates and times as UTC, or UTC + time zone offset, and these cover the most common use cases. You can use these formats to communicate with clients, and have clients do the conversion for you, for example, in a browser you can use Date.getTimezoneOffset. One good thing about this is that if the time zone data is incorrect on a client's device, there is a reasonable chance that the client's clock is also showing the wrong time anyway. Most client OSs are aggressively updated so this is mostly solved. The remaining problems are any systems that need to do calendrical math, for example, calendar programs.

In practice, however, people write bad date/time code often enough that it’s a problem. I was recently using a client library that was completely broken if the client’s system had a negative offset from UTC more than 1 hour.

At work we get emails if we leave any container running that was built too long ago (three months or something?)

Re: News for the tz database

#10

Post by mikelward » Sat, Jul 28, 2018, 3:40 PM UTC

> Use "PST" and "PDT" for Philippine time.

I wonder if this will break anything. Some systems make the bad assumption that timezone abbreviations are unique, e.g. when parsing dates.