How will Postgresql upgrades work if they are running inside containers?

[ehelms]

We are versed in how Postgresql upgrades happen when using operating system packages but don't know how it is handled when Postgresql is running in containers. This issue is to research and understand how that process occurs and if it affects the design.

[ekohl]

Commonly pg_upgrade is used. This requires both the old and new installations to be present. AFAIK today postgresql-setup on EL wraps this as well. https://pat-s.me/performing-postgresql-major-version-upgrades-in-docker/ points to https://github.com/tianon/docker-postgres-upgrade.

Other approaches I saw online basically came down to doing a full DB dump and restore, which will be a lot slower.

[evgeni]

Quoting myself from #62:

The container does support running pg_upgrade if it starts with existing data and POSTGRESQL_UPGRADE variable was set:

• https://github.com/sclorg/postgresql-container/blob/e65d040374930106672d88a26b275ee02e56ab37/13/root/usr/bin/run-postgresql#L27
• https://github.com/sclorg/postgresql-container/blob/e65d040374930106672d88a26b275ee02e56ab37/13/root/usr/share/container-scripts/postgresql/common.sh#L408

So we might be rather lucky here and be able to orchestrate updates in a very similar way we do on base rhel