deleting particular rows takes longer time to execute oracle. have to kill the session <p>I have 3 tables Attribute_type, Attribute, Attribute_assignment which is referencing one another. Attribute has Attribute_id + Attribute_type_id, Attribute_assignment has Assignment_id + Attribute_id + Attribute_type_id</p> <p>There are some stale data in Attribute_assignment, whose parents are deleted and its dangling. So i tried to delete those rows. Few got deleted very easily , but last 4 rows are not getting deleted at all. It just takes long time. Because of this I am not able to add constraints as well. </p> <p>Please suggest.</p>