[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-3958) Superfluous generated updates cause Violation of UNIQUE KEY constraint

Superfluous generated updates cause Violation of UNIQUE KEY constraint ---------------------------------------------------------------------- Key: HHH-3958 URL: https://hibernate.onjira.com/browse/HHH-3958 Project: Hibernate ORM Issue Type: Bug Components: core Affects Versions: 3.3.1 Environment: 3.3.1 GA, SQLServer 2008 Reporter: Guenther Demetz Priority: Minor Attachments: Testcase.jar When deleting a entire closure of objects associated over @ManyToOne within one single transaction, then on commit the FlushEventListener creates update statements on objects which are going to be deleted anyway. These update statements seems not only be useless, in certain scenarios they lead to Constraint Violation Exceptions, see the example here: @Entity public class A { public A() { } @Id @GeneratedValue private long oid; } @Entity @Table(uniqueConstraints = {@UniqueConstraint(columnNames={"assA_oid"})}) public class B { public B() {}; @Id @GeneratedValue private long oid; @javax.persistence.ManyToOne protected A assA = null; } A a1 = new A(); em.persist(a1); A a2 = new A(); em.persist(a2); B b1 = new B(); b1.assA = a1; // set unique association B b2 = new B(); b2.assA = a2; // set unique association em.persist(b1); em.persist(b2); em.getTransaction().commit(); em.getTransaction().begin(); em.remove(a1); em.remove(a2); em.remove(b1); em.remove(b2); em.getTransaction().commit(); // p6spy report: // update B set assA_oid='',version=0 where oid=1 and version=0 // update B set assA_oid='',version=0 where oid=2 and version=0 --> this raises "Violation of UNIQUE KEY constraint on all DB's which don't allow multiple null values in a unique index See testcase in attachment