On Wed, Nov 6, 2019 at 12:02 PM Adrian Klaver <adrian.klaver@xxxxxxxxxxx> wrote: > On 11/5/19 3:00 PM, Chris Withers wrote: > > Hmm. Is there any option to use the system timezone packages? > > https://www.postgresql.org/docs/11/install-procedure.html > > --with-system-tzdata=DIRECTORY By the way, you can see if your installation of PostgreSQL was built to use system-provided tzdata by running the pg_config program that was installed alongside it. That could be useful if it was built by a package maintainer (Debian etc) and you want to see how they configured it. You'll see something like CONFIGURE = '... --with-system-tzdata=/usr/share/... ' if it's using OS vendor tzdata files. 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. Once I was involved in rolling out a last minute DST rule change that happened in Australia due to politicians and an international sporting event, and we had to go hunting for copies of tzdata hiding on our servers that had to agree on when the financial markets were opening... we found many copies, and ever since then I complain wherever I see packages shipping their own copies of this stuff... Assuming you are using system tzdata, your other question was what you need to do after the tzdata files have been updated. I suspect that new PostgreSQL database sessions (processes) will see the new rules, but existing sessions may continue to see the old rules if they had loaded them already, because we cache them in per-process memory (see pg_tzset()). It would probably be safest to restart the PostgreSQL cluster. If you're using PostgreSQL's build-in tzdata, then you'll need to restart your cluster anyway once you install the version that shipped with the new tzdata rules, and depending on your package manager, that might happen automatically when you upgrade. *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.
