Thank you for the pointers! The good thing about the Doctrine's DBAL is that is not connected to the ORM and you don't have to use it construct queries if you don't want to. I'd say we should trying using it just for schema creation/compare and update.
So the closest RFC to this is https://www.mediawiki.org/wiki/Requests_for_comment/Abstract_table_definitions. Doctrine's way to represent the schema is http://docs.doctrine-project.org/projects/doctrine-dbal/en/latest/reference/schema-representation.html which kind of looks similar. But of course the devil is in the details.