Please add safeguards for drops on tables and indexes

[LearningRoutesIT]

I think drops should be part of optional strategy which should be opt able for Devs and by default it should avoid it. This is a big setback for production databases acquiring transactional data in real time.

[CaselIT]

Hi,

I think it's out of scope of alembic / sqlalchemy to provide such safeguards.
In case of alembic you can just as well do op.execute('drop table my_table') and what you are proposing would not block such cases. Or you could do op.execute('delete from my_table where true').

Overall the only safeguard is to verify that the upgrade script does what you expect and to have test env were you can test your changes on. backup also help