a sequence of update operations which can be applied in sequence to bring the schema from any previous version up to the latest version, migrating existing data in the process.
Most recent known version, to which the schema will be updated.
Compare the schema version found in the DB with the latest version, and return a tuple showing the update to be applied, if needed.
a sequence of update operations which can be applied in sequence to bring the schema from any previous version up to the latest version, migrating existing data in the process.
a sequence of update operations which can be applied in sequence to bring the schema from any previous version up to the latest version, migrating existing data in the process.