DropOp dependency ordering when dropping multiple associated entities about alembic_utils

[olirice]

The behavior your seeing is related to not doing dependency order resolution for the alembic DropOp

When resolution order is a problem the best bet is to break the migration down into smaller chunks:

For example, you could

• drop trigger A
• autogen migration
• drop function A
• autogen migration
• create new function B and trigger B
• autogen migration

alternatively, you could continue dropping both at the same time and manually re-order the drop_entity calls in the autogen'ed migration

---

Possible approaches to solving this upstream (if you'd like to submit a PR would be to update here

alembic_utils/src/alembic_utils/replaceable_entity.py

Lines 391 to 400 in fb39689

	# No match was found locally
	# If the entity passes the filters,
	# we should create a DropOp
	upgrade_ops.ops.append(DropOp(db_entity))
	logger.info(
	"Detected DropOp op for %s %s",
	db_entity.__class__.__name__,
	db_entity.identity,
	)

To

1. Order the drops so that PGTrigger is always first (this would solve you problem but not all problems)
2. Collect a list of the entities planned for dropping and then do drop order resolution before appending to upgrade_ops equivalent to

   alembic_utils/src/alembic_utils/depends.py

   Line 13 in fb39689

   def solve_resolution_order(sess: Session, entities):

where either implementation would need tests like this one https://github.com/olirice/alembic_utils/blob/master/src/test/test_depends.py

[tauseef13bok]

Hi .I created a fork , to solve the dependency ordering . My fork supports ordering of nested dependencies for both create and drop operation. Could you have a look?

[olirice]

If you could open a PR an annotate the changes I'd be happy to take a look!

[tauseef13bok]

Sure. done.