Dangers in dropping all tables in a schema with CASCADE

Question

The answer to this question suggests I can use the CASCADE option of DROP SCHEMA to remove all a schema and all its tables, but warns:

CASCADE - Automatically drop objects (tables, functions, etc.) that are contained in the schema, and in turn all objects that depend on those objects

Being a novice to databases, I'm unsure about what objects may depend on objects within a schema. Is it possible that a table or some other object outside the schema that is dependent on an object inside the schema will be dropped as well? If I just want to eliminate a schema and all its contents without changing anything else, is using CASCADE a good idea?

Answer 1

run it in a transaction, you'll get warnings for every cascading drop, ROLLBACK if don't like what you see.

Answer 2

I can't think of a case where an ordinary table in a different schema would get dropped.

If there is a foreign key constraint between tables in different schemas, the constraint itself would get dropped but the table in the non-dropped schema would not get dropped.

If the dropped schema contained a type which was used for a column in a table in a different schema, then that column of that table would get dropped, but the table itself would not.

I think the only real answer to this type of question is "try it in a test instance and see if you like the result". In this case, you should be able to set up a test instance with just the objects, not the data itself (e.g. using pg_dump -s on production and replaying it into the test server) and very quickly test it out and see what objects get dropped.