Rails initializer to check >= PG11 and otherwise warn in a helpful way
We just merged !35168 (merged) which gives the first example of using hash partitioning. This also uses foreign keys on the partitioned table, so this in fact requires PG11.
Internally, we've had GDK setups still on PG10 which blew up on this migration.
The idea here is to add a Rails initializer that makes sure we're on >=PG11 and if not, it
fails warns loudly with a clear explanation of what's happening.
So this is an extension of the already existing initializer: Add a version check to it. https://gitlab.com/gitlab-org/gitlab/blob/ab/revert-schema-create/config/initializers/1_postgresql_only.rb#L4