[zzzzzzzza]

the ddl that creates the views/tables/triggers that replace the "idempotent code" should also be idempotent so you should be able to roll it back without rolling back any data

actually i wrote a couple tables/stored procedures that (should probably mostly) do this for postgres after looking at some other patch management libraries by depesz and steve purcell a couple weeks ago

https://github.com/NotBrianZach/postgres-sql-migrate