I really just want a deterministic (or sync-based) migration tool. The only two I'm aware of are Innovartis DBGhost and RedGate SQL Compare (though RedGate requires a license everywhere it runs, whereas DBGhost only requires a license to compile the package).

This stems from my work years ago with databases in on-premise products. Customers would modify the database schema, causing migration "up" scripts to fail, and it would be very difficult (and manually intensive) to baseline everything again and get the database back to a working state. Even though modifying the schema was clearly laid out as "not supported", it would still be something we'd have to fix, because ultimately they (and their account reps, etc) still need the product to work.

We used DBGhost, and then had custom pre- and post-deployment scripts to do certain types of changes, such as renaming a column (`if exists old_column { add new column; copy old to new; drop old_column; }`), or adding expensive indexes. One of the best parts is all it stores in source control is all the CREATE scripts for database objects (and the custom pre/post deployment scripts). Pull requests would let you trivially see a new column or index being added.

Compared to the pain of creating and maintaining up/down scripts and the long-term problem where deploying a new instance takes thousands of migration steps (or risking the inital CREATE scripts not matching what happens after all migrations), doing a schema sync was significantly simpler in nearly every respect.

I've been looking for something similar for Postgres and MySQL/MariaDB without any luck, and it really surprises me there's not more interest in doing migrations this way.