Upgrade Ubuntu 22 -> 24 may break PostgreSQL

'Tis the season again.

Ubuntu 24.04.1 has just been released, so many Ubuntu LTS users will now
be prompted to upgrade from 22.04 to 24.04.

A word of warning to those who use Postgresql from the Ubuntu repo (not
PGDG):

As usual, a newer Ubuntu version comes with a newer Postgres version (16
instead of 14). Also as usual, I got a message during the upgrade that
Postgres 14 is obsolete,. but the binaries have been left installed and
I should upgrade to Postgres 16 manually ASAP.

But after the reboot, PostgreSQL failed to start because it needed a
shared library (libldap) which was no longer there. So a normal
pg_upgradecluster wouldn't work.

In my case the quickest way to recover was to install postgresql-14 on a
VM, copy the data direcory into that instance and make a fresh dump,
then install postgresql-16 on my laptop and restore the dump. Annoying,
but no big deal for the small test database I keep on my laptop. If you
have multi-terabyte databases, your situation may be different.

I'm not exactly sure what went wrong (I got some conflicts during the
upgrade and maybe I shouldn't have invoked apt autoremove?), and you may
not have this problem, but make sure you have a backup before the
upgrade.

hp

--
_ | Peter J. Holzer | Story must make more sense than reality.
|_|_) | |
| | | hjp(at)hjp(dot)at | -- Charles Stross, "Creative writing
__/ | http://www.hjp.at/ | challenge!"