ban-drop-sequence

problem

Dropping a sequence may break existing clients. For example, an earlier application revision may still call nextval('s') after a database migration drops s. Rolling back the application does not restore the sequence, so that call fails. CASCADE can also remove defaults that depend on the sequence.

DROP SEQUENCE IF EXISTS s CASCADE;

solution

Update clients to stop using the sequence. Keep it until all running application revisions, including any revision used for rollback, no longer depend on it. Drop the sequence in a later migration.