Problem/Motivation
The 3 modules Migrate, Migrate_drupal, Migrate_drupal_ui didn't implement any method to remove these tables or other data related to migration and have no use after complete migration.
After uninstall of migration modules the tables created are not removed. It is not reasonable to not have a mechanism to remove these tables.
Why are these tables left after uninstall of the migration modules
Since this is frequently asked, here is a summary.
The tables remain after the migration because they provide the necessary information to fix problems that may discovered later, even after initial testing of the migration results. It is completely up to you to choose when to remove the migrate tables. But do so with the knowledge that if problems appear later and are traced back to the migration, it will be very difficult, if possible at all, to fix. See #11 and #22
Proposed resolution
Add the method dropTables()to the existing sql id map concrete class (w/o any interface). Then we can just do an instance_of check when we iterate over id maps and only call the sql based ones.
Remaining tasks
- Add method
- Add tests