hibernate insert to a collection causes a delete then all the items in the collection to be inserted again

Question

I have a many to may relationship CohortGroup and Employee. Any time I insert an Employee into the CohortGroup hibernate deletes the group from the resolution table and ins

Answer 1

You have to define hashCode() and equals() on your CohortGroup and Employee entities. This can be done automatically by your IDE and it can either be on the primary key (sometimes not a good idea) or on a business key (preferable).

Read this article.