When a DROP USER statement is processed, the system places an EXCLUSIVE lock on the user being dropped.
Among the dictionary locks required for dropping the user, WRITE locks for deleting privileges from the partitioned DBC.AccessRights table are placed as follows:
- An all-AMP WRITE lock is placed on the partition range assigned to objects in the dropped user/database. Although DROP USER can only be executed after all objects in the user have been dropped, a final delete is done to clean up any leftover privileges on the user's dropped objects.
- For DROP USER only, an optional single-AMP WRITE lock is placed on the user's RowHash in all partitions if the user has been granted explicit privileges on objects in other users or databases that need to be deleted.