I've got a REST interface to a database, implemented in Python FastAPI + SQLAlchemy. I want to run some (relatively) costly operations on my data, such as calculating cryptographic hashes or signatures. My hope is to be able to:

1. Perform the insert, so that all referential integrity is checked by the database.
2. Return the REST response to the front-end (primary key of insert).
3. Asynchronously calculate the costly hash/signature/whatever, and update into the DB (same table).

I'd prefer to have a cross-database solution, but it seems running a trigger on insert/update might be the way to go. If so, my target in production is PostgreSQL.

Does anyone have a suggested approach they'd favour?