[tz] Doubt about releases/updates

John Haxby john.haxby at oracle.com
Wed Nov 30 17:40:11 UTC 2016

On 30/11/16 17:27, Pablo Sánchez wrote:
> I have a doubt about the TZ database release or updates, and maybe you
> can help me to solve it.
> So, is the database update BEFORE or AFTER a new DST has started? The
> reason why I need to know it is because we are having issues about
> calculating some ETAs and presenting the information on reports, because
> PHP internal database doesn't get updates automatically. So we decided
> to use an extension that uses IANA's Timezone Database (updated
> approximatelly 23 times an year). So, we need to know if those updates
> are released before the daylight saving time starts or if you release it
> before it starts. Since there are usually political decisions that
> delays or rushes the DST beginning, I believe those updates comes prior
> to the actual fact, with a data on wich day begin, so I should not worry
> on using the extension that updates itself with 24 hours delay, right?
> So, do you update it before DST comes, or after?

It would make little or no sense to publish a tzdata update after the
changes in it take effect.

Whenever possible changes are pushed out as soon as they are confirmed
which is before the time transition will take effect.   On a few
memorable occasions a government has changed the timezone with no notice
at all and that has caused problems for everyone involved.


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