coderholic/django-cities — pull request #29 by ItsNotWorking (2012-02-21 15:56:23+00:00)
Title: Convert postal_codes.code to primary_key

If you run the import script again after you have imported all postcodes, all the primary keys could end up referencing different postcodes. Postcodes are a unique property and should therefore be the unique identifier in any postcode table.

Thanks