Re: here does postgres take its timezone information from?

> 6 nov. 2019 kl. 03:03 skrev Thomas Munro <thomas(dot)munro(at)gmail(dot)com>:
>
> On Wed, Nov 6, 2019 at 2:20 PM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Thomas Munro <thomas(dot)munro(at)gmail(dot)com> writes:
>>> On Wed, Nov 6, 2019 at 12:02 PM Adrian Klaver <adrian(dot)klaver(at)aklaver(dot)com> wrote:
>>>> On 11/5/19 3:00 PM, Chris Withers wrote:
>>>>> Hmm. Is there any option to use the system timezone packages?
>>
>>>> --with-system-tzdata=DIRECTORY
>>
>>> I hope that most distributions do that*, because otherwise you
>>> could finish up with lots of out-of-sync copies of the tzdata database
>>> inside your database, your JVM, your libc, etc etc, and you want a
>>> single source of truth for that stuff.
>>
>> Right. Our recommendation is to use --with-system-tzdata if you're on
>> a platform where the vendor updates their copy of tzdata regularly.
>> The fact that we supply a copy of tzdata at all is really just a fallback
>> for folks on poorly-supported platforms. (Naming no names here ...)
>
> Incidentally, that's also why I don't want to give up on libc
> collations quite as easily as some, despite their limitations. It
> should be possible to get all the software on your system to agree on
> the ordering of two strings and the current time!
>
>>> *It looks like FreeBSD's port uses the copy of tzdata from the
>>> PostgreSQL source tree by default and thus that is what you get if you
>>> install PostgreSQL with "pkg". That's not a great default IMHO and
>>> should be changed.
>>
>> Ugh. Who can we poke there?
>
> Maybe Palle? (CCed).

Hi,

The decision to use postgresql's tzdata is quite old. It was based on the assumption that postgres is updated more frequently than the operating system, and that for that reason it was better to use postgresql's tzdata, since it would be more accurate more often. This is probably not true anymore, so I agree it should probably be changed to default=system-tzdata on FreeBSD.

I will commit an upgrade in Thursday, and unless anybody raise their voice against it, I will change the default setting then.

Regards,
Palle