[11.x] [policy] Require PostgreSQL 16 for Drupal 11

Cross-linking the MySQL issue directly too.

Updating title, tags and version number based on recent announcement at https://www.drupal.org/about/core/blog/new-drupal-core-branching-scheme-...

With the two year release cadence PG 15 makes sense:

• Drupal 11 release Dec 2024, support 'til Mar 2029?
• The only version that comes close in terms of base support is 15 (16 & 17 will likely be out by then).
• 15 is in Ubuntu 22.04 LTS jammy (standard support ends Apr 2027, though +5-year cover available) and will be in Debian 12 bookworm (likely end LTS June 2028, with similar caveat for extended LTS). Users of Ubuntu 20.04 fossil and Debian 11 bullseye would have to use PostgreSQL's own repository.
• RHEL 9 initially provided 13 but their own install page explains how to get 15 in RHEL 9.2.
• SUSE Linux Enterprise Server 15 SP4 currently supports PostgreSQL 14, but has a SP5 beta out with PostgreSQL 15 that people must upgrade to. (SUSE Linux Enterprise Server 12 support ends 31 Oct 2024.)

Honestly PostgreSQL 16 would be a better match in terms of upstream timelines but obviously not for most distributions, and it is not clear that the changes are that significant from a development perspective. PostgreSQL 15 at least added MERGE and wider ICU collation support. Perhaps those coding the DB layer could chime in on features that might be important.

PostgreSQL 16 was released in September 2023 and will be in Debian Trixie. Given the longer support cycle for Drupal 10 I think it would be fine to require that - it will be coming through in distributions next year around when we're releasing Drupal 11, even if it's not widespread now.

+1 to PostgreSQL 16, as it seems like it is going to be included in next major Debian and Ubuntu releases.

Bumping to critical because we need to decide this six months before the June release window, which is soon.

It depends on whether we expect people to [be able to] upgrade to the latest available distro, or whether we want to work with PG from all distros that are still supported during part of the release period.

My experience is that sometimes you have a server and have to use it without potentially breaking other stuff by updating to a new version of a distro - especially if it's not your server to start with. But I'm not someone who installs lots of sites, and I imagine when you do that the process is to install a new OS too, perhaps by plonking it into a container. (It's also viable to install multiple versions of PostgreSQL on Drupal-derived distros, which isn't quite so easy for e.g. SQLite. But for RHEL/CentOS 7 and similar distributions this only works up to PostgreSQL 15.)

There's no doubt that PostgreSQL 16 has many improvements but few of them seem to relate to programming features - is the use of syntax such as JSON_ARRAY(), JSON_ARRAYAGG(), and IS JSON beneficial enough to say "you can't install without PG 16"? I didn't hear people speaking up when I asked about features.

As I said before, PG 16 matches the Drupal support lifetime better. I'm using it now on Drupal Bookworm using PostgreSQL's APT repo. I just want us to be clear that the cost is that in some cases Drupal 11 won't be usable with PostgreSQL on a still-supported system without being able to upgrade the OS or add a new repo and binaries for PG 16.

Re-titling so it's easier to see what the proposed resolution is now that there is one.

I doubled checked the Debian and Ubuntu release schedules and I agree with PostgreSQL 16.

I have updated Database server requirements and I see that there is already a Postgresql 16.0 test container, added in #3240346: Add Postgresql 15.4/16.0 to CI.

I opened #3421175: Update INSTALL.txt and hook_requirements() etc. with remaining Drupal 11 platform requirements to do when 11.x is ready for it.

This needs a CR. There can be a single CR for all the D11 DB requirements.

Change record added.