[19.0][IMP] database_cleanup: Drop dependent views before dropping tables

[quoc-pn]

Problems

The current implementation only removes constraints before dropping tables. However, PostgreSQL also prevents dropping a table when other database objects, such as views or materialized views, depend on it.

psycopg2.errors.DependentObjectsStillExist: cannot drop table hr_employee because other objects depend on it
DETAIL:  view hr_employee_public depends on table hr_employee
view hr_holidays_remaining_leaves_user depends on table hr_employee
view hr_leave_report_calendar depends on table hr_employee
HINT:  Use DROP ... CASCADE to drop the dependent objects too.

Solution

Before dropping a table, detect and remove all views or materialized views that reference the table. Once the dependent objects have been removed, the table can be dropped safely without raising DependentObjectsStillExist.