PostgreSQL 19 support in packaging images

[ihalatci]

Tracking issue for PostgreSQL 19 support in the packaging build images.

Current state

Initial support is being added in #1203:

• deb (templates/Dockerfile-deb.tmpl + generated dockerfiles/*-all/Dockerfile): the extra 19 component is appended to the PGDG apt source line (deb http://apt.postgresql.org/pub/repos/apt/ <release>-pgdg main 19), build deps switched to postgresql-server-dev-19, and DEB_PG_SUPPORTED_VERSIONS extended to 14 15 16 17 18 19.
• rpm (templates/Dockerfile-rpm.tmpl + dockerfiles/almalinux-9-pg19/): the pgdg19-updates-testing repo is enabled via sed on pgdg-redhat-all.repo, because the GA repo (pub/repos/yum/19/redhat/...) does not exist yet.
• version lists: 19 added to update_dockerfiles, update_image, and ci/push_images.
• CI matrices: PG19 is added as a one-off include entry (almalinux,9 only) in build-package.yml, build-package-test.yml, and image-health-check.yml, rather than in the main POSTGRES_VERSION cross-product list.

Nothing pins a specific beta (beta1/beta2/beta3); packages are installed unpinned, so a rebuild always picks up the newest 19 build PGDG publishes.

Known limitations while PG19 is pre-GA

• No EL8 packages. PGDG publishes no PostgreSQL 19 RPMs for EL8 — testing/19/redhat/rhel-8-x86_64/ is empty while rhel-9-x86_64/ is populated. update_dockerfiles, update_image, and ci/push_images therefore guard against release=8 + pgversion=19, and this is also why PG19 is an include entry in the CI matrices instead of being in the main list (the cross-product would otherwise pull in almalinux,8 and oraclelinux,8).
• Beta packages come from the testing channel. The RPM images depend on pgdg19-updates-testing; the deb images depend on the version-specific 19 component of the pgdg archive. Both are pre-GA mechanisms.

TODOs after PostgreSQL 19 GA

• rpm — drop the testing repo enable. Remove the sed -i '/\[pgdg19-updates-testing\]/...' line from templates/Dockerfile-rpm.tmpl and the pg19_sed_cmd conditional from update_dockerfiles, then regenerate with ./update_dockerfiles. Verify https://download.postgresql.org/pub/repos/yum/19/redhat/rhel-9-x86_64/ exists first (it currently 404s).
• deb — drop the extra 19 component. Revert the pgdg source line in templates/Dockerfile-deb.tmpl back to ... <release>-pgdg main once PG19 packages land in the default main component, then regenerate.
• Re-check EL8 availability. If PGDG ships PG19 for EL8 at GA, remove the release=8 guards in update_dockerfiles, update_image, and ci/push_images, and generate the almalinux-8-pg19 / oraclelinux-8-pg19 images. If EL8 remains unsupported (likely, given EL8 is near EOL), keep the guards and leave a short comment recording that it is permanent.
• Fold PG19 into the main CI matrices. Once the EL8 question is settled, move 19 from the include block into the POSTGRES_VERSION list in build-package.yml, build-package-test.yml, and image-health-check.yml (or keep the include if EL8 stays excluded).
• Rebuild and push images so the published citus/packaging tags carry GA PostgreSQL 19 rather than a beta build.
• Extend PG19 to the remaining RPM platforms if PGDG coverage grows beyond EL9 (e.g. EL10) by the time of GA.
• Update the release-side PostgreSQL version matrix (postgres-matrix.yml on the all-citus branch) once Citus itself declares PG19 support, so packages are actually built against PG19.