Updating an entity and many relationships: database vs application layer

Question

We are working on a transformation project

It has records in table entityA and entityB, which has a relation entityAB. We need to delete records in table entityA and recreate them with some other parameters, lets say new records are rowA'. Now based on user input of matching between rowA and rowA', we need to update records of relationAB to relationA'B, that is where rowA used to be now rowA' will be.

For doing this there are 2 approaches:

1. Do complete processing of taking backup, updating relation using sql procedures(pl/sql).
2. Do transformation of records in application server and persist them in db.

We have oracle 12c server, java8, hibernate, spring boot as our technology stack.

Which approach is better?

constraints

1. Fast completion of transformation(code wise).
2. Low maintenance, easy to extend.
3. Concurrent updates are not there.
4. large number of records to be processed.
5. many relations like relationAC, relationAD which also needs to be updated.
6. (Business wise)transformation can take long duration, like taking backup and deleting inventory may have a duration of a week or more, because of business constraints.