Hibernate version: Hibernate 3.0 beta 4

Mapping documents:

<?xml version="1.0"?>

<!DOCTYPE hibernate-mapping PUBLIC
"-//Hibernate/Hibernate Mapping DTD 3.0//EN"
"http://hibernate.sourceforge.net/hibernate-mapping-3.0.dtd">

<hibernate-mapping default-access="field">

<class name="Parent" table="Parent">
<id name="id" column="ParentID" type="integer">
<generator class="native"/>
</id>

<set name="childs" lazy="true" inverse="true" cascade="all-delete-orphan">
<key column="ParentID" on-delete="cascade"/>
<one-to-many class="Child"/>
</set>
</class>

<class name="Child" table="Child">
<id name="id" column="ChildID" type="integer">
<generator class="native"/>
</id>

<many-to-one name="parent" column="ParentID" not-null="true" cascade="none"
foreign-key="FK_Child_Parent"/>

<many-to-one name="subChild" column="SubChildID" cascade="all"
foreign-key="FK_Child_SubChild"/>

</class>

<class name="SubChild" table="SubChild">
<id name="id" column="SubChildID" type="integer">
<generator class="native"/>
</id>
</class>

</hibernate-mapping>

Code between sessionFactory.openSession() and session.close():

public static void main(String args[])
{
Configuration cfg = new Configuration();

cfg.configure("hibernate.cfg.xml");

cfg.setProperty(Environment.HBM2DDL_AUTO, "create");

SessionFactory factory = cfg.buildSessionFactory();

addTestData(factory);

deleteTestData(factory);

factory.close();
}

static void addTestData(SessionFactory factory)
{
Session s = factory.openSession();

Transaction tx=null;

try
{
tx = s.beginTransaction();

Parent parent = new Parent();

Child child = new Child();

child.setSubChild( new SubChild() );

parent.addChild(child);

s.save(parent);

tx.commit();
}
catch( RuntimeException e )
{
if (tx!=null) tx.rollback();
throw e;
}
finally { s.close(); }
}

static void deleteTestData(SessionFactory factory)
{
Session s = factory.openSession();

Transaction tx=null;

try
{
tx = s.beginTransaction();

List<Parent> list = (List<Parent>)s.createCriteria(Parent.class).list();

for( Parent parent: list )
{
System.out.println("Deleting "+parent);

s.delete(parent);
}

tx.commit();
}
catch( RuntimeException e )
{
if (tx!=null) tx.rollback();
throw e;
}
finally { s.close(); }

Full stack trace of any exception that occurs:

org.hibernate.exception.ConstraintViolationException: could not delete: [SubChild#1]
at org.hibernate.exception.SQLStateConverter.convert(SQLStateConverter.java:63)
at org.hibernate.exception.JDBCExceptionHelper.convert(JDBCExceptionHelper.java:43)
at org.hibernate.persister.BasicEntityPersister.delete(BasicEntityPersister.java:2005)
at org.hibernate.persister.BasicEntityPersister.delete(BasicEntityPersister.java:2133)
at org.hibernate.action.EntityDeleteAction.execute(EntityDeleteAction.java:61)
at org.hibernate.engine.ActionQueue.execute(ActionQueue.java:239)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:223)
at org.hibernate.engine.ActionQueue.executeActions(ActionQueue.java:141)
at org.hibernate.event.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:271)
at org.hibernate.event.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:24)
at org.hibernate.impl.SessionImpl.flush(SessionImpl.java:719)
at org.hibernate.transaction.JDBCTransaction.commit(JDBCTransaction.java:84)
at OnDeleteTest.deleteTestData(OnDeleteTest.java:74)
at OnDeleteTest.main(OnDeleteTest.java:20)
Caused by: java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]DELETE statement conflicted with COLUMN REFERENCE constraint 'FK_Child_SubChild'. The conflict occurred in database 'BirdDB', table 'Child', column 'SubChildID'.
at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processErrorToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReplyToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRPCRequest.processReplyToken(Unknown Source)
at com.microsoft.jdbc.sqlserver.tds.TDSRequest.processReply(Unknown Source)
at com.microsoft.jdbc.sqlserver.SQLServerImplStatement.getNextResultType(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.commonTransitionToState(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.postImplExecute(Unknown Source)
at com.microsoft.jdbc.base.BasePreparedStatement.postImplExecute(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.commonExecute(Unknown Source)
at com.microsoft.jdbc.base.BaseStatement.executeUpdateInternal(Unknown Source)
at com.microsoft.jdbc.base.BasePreparedStatement.executeUpdate(Unknown Source)
at org.hibernate.jdbc.NonBatchingBatcher.addToBatch(NonBatchingBatcher.java:23)
at org.hibernate.persister.BasicEntityPersister.delete(BasicEntityPersister.java:1988)
... 11 more

Name and version of the database you are using:
MSSQL 2000 SP3 Desktop Edition

The generated SQL (show_sql=true):

Hibernate: insert into Parent default values select scope_identity()
Hibernate: insert into SubChild default values select scope_identity()
Hibernate: insert into Child (ParentID, SubChildID) values (?, ?) select scope_identity()
Hibernate: select this_.ParentID as ParentID0_ from Parent this_
Hibernate: select childs0_.ParentID as ParentID__, childs0_.ChildID as ChildID__, childs0_.ChildID as ChildID0_, childs0_.ParentID as ParentID1_0_, childs0_.SubChildID as SubChildID1_0_ from Child childs0_ where childs0_.ParentID=?
Hibernate: select subchild0_.SubChildID as SubChildID0_ from SubChild subchild0_ where subchild0_.SubChildID=?
Hibernate: delete from SubChild where SubChildID=?

Debug level Hibernate log excerpt:

Excerpt from log starting from object deleting:

DEBUG hibernate.event.DefaultDeleteEventListener - deleting a persistent instance
DEBUG hibernate.event.DefaultDeleteEventListener - deleting [Parent#1]
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.engine.Cascades - processing cascade ACTION_DELETE for: Parent
DEBUG hibernate.engine.Cascades - cascade ACTION_DELETE for collection: Parent.childs
DEBUG hibernate.event.DefaultInitializeCollectionEventListener - initializing collection [Parent.childs#1]
DEBUG hibernate.event.DefaultInitializeCollectionEventListener - checking second-level cache
DEBUG hibernate.event.DefaultInitializeCollectionEventListener - collection not cached
DEBUG hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
DEBUG org.hibernate.SQL - select childs0_.ParentID as ParentID__, childs0_.ChildID as ChildID__, childs0_.ChildID as ChildID0_, childs0_.ParentID as ParentID1_0_, childs0_.SubChildID as SubChildID1_0_ from Child childs0_ where childs0_.ParentID=?
DEBUG hibernate.jdbc.AbstractBatcher - preparing statement
DEBUG hibernate.type.IntegerType - binding '1' to parameter: 1
DEBUG hibernate.jdbc.AbstractBatcher - about to open ResultSet (open ResultSets: 0, globally: 0)
DEBUG hibernate.loader.Loader - result set contains (possibly empty) collection: [Parent.childs#1]
DEBUG hibernate.engine.CollectionLoadContext - uninitialized collection: initializing
DEBUG hibernate.loader.Loader - processing result set
DEBUG hibernate.loader.Loader - result set row: 0
DEBUG hibernate.type.IntegerType - returning '1' as column: ChildID0_
DEBUG hibernate.loader.Loader - result row: EntityKey[Child#1]
DEBUG hibernate.loader.Loader - Initializing object from ResultSet: [Child#1]
DEBUG hibernate.persister.BasicEntityPersister - Hydrating entity: [Child#1]
DEBUG hibernate.type.IntegerType - returning '1' as column: ParentID1_0_
DEBUG hibernate.type.IntegerType - returning '1' as column: SubChildID1_0_
DEBUG hibernate.type.IntegerType - returning '1' as column: ParentID__
DEBUG hibernate.loader.Loader - found row of collection: [Parent.childs#1]
DEBUG hibernate.engine.CollectionLoadContext - reading row
DEBUG hibernate.type.IntegerType - returning '1' as column: ChildID__
DEBUG hibernate.event.DefaultLoadEventListener - loading entity: [Child#1]
DEBUG hibernate.event.DefaultLoadEventListener - entity found in session cache
DEBUG hibernate.event.DefaultLoadEventListener - attempting to resolve: [Child#1]
DEBUG hibernate.event.DefaultLoadEventListener - resolved object in session cache: [Child#1]
DEBUG hibernate.loader.Loader - done processing result set (1 rows)
DEBUG hibernate.jdbc.AbstractBatcher - about to close ResultSet (open ResultSets: 1, globally: 1)
DEBUG hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
DEBUG hibernate.jdbc.AbstractBatcher - closing statement
DEBUG hibernate.loader.Loader - total objects hydrated: 1
DEBUG hibernate.engine.TwoPhaseLoad - resolving associations for [Child#1]
DEBUG hibernate.event.DefaultLoadEventListener - loading entity: [Parent#1]
DEBUG hibernate.event.DefaultLoadEventListener - entity found in session cache
DEBUG hibernate.event.DefaultLoadEventListener - attempting to resolve: [Parent#1]
DEBUG hibernate.event.DefaultLoadEventListener - resolved object in session cache: [Parent#1]
DEBUG hibernate.event.DefaultLoadEventListener - loading entity: [SubChild#1]
DEBUG hibernate.event.DefaultLoadEventListener - creating new proxy for entity
DEBUG hibernate.engine.TwoPhaseLoad - done materializing entity [Child#1]
DEBUG hibernate.engine.CollectionLoadContext - 1 collections were found in result set
DEBUG hibernate.engine.CollectionLoadContext - collection fully initialized: [Parent.childs#1]
DEBUG hibernate.engine.CollectionLoadContext - 1 collections initialized
DEBUG hibernate.engine.PersistenceContext - initializing non-lazy collections
DEBUG hibernate.event.DefaultInitializeCollectionEventListener - collection initialized
DEBUG hibernate.engine.Cascades - cascading to delete: Child
DEBUG hibernate.event.DefaultDeleteEventListener - deleting a persistent instance
DEBUG hibernate.event.DefaultDeleteEventListener - deleting [Child#1]
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.engine.Cascades - processing cascade ACTION_DELETE for: Child
DEBUG hibernate.engine.Cascades - done processing cascade ACTION_DELETE for: Child
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.engine.Cascades - processing cascade ACTION_DELETE for: Child
DEBUG hibernate.engine.Cascades - cascading to delete: SubChild
DEBUG hibernate.event.DefaultLoadEventListener - attempting to resolve: [SubChild#1]
DEBUG hibernate.event.DefaultLoadEventListener - object not resolved in any cache: [SubChild#1]
DEBUG hibernate.persister.BasicEntityPersister - Materializing entity: [SubChild#1]
DEBUG hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
DEBUG org.hibernate.SQL - select subchild0_.SubChildID as SubChildID0_ from SubChild subchild0_ where subchild0_.SubChildID=?
DEBUG hibernate.jdbc.AbstractBatcher - preparing statement
DEBUG hibernate.type.IntegerType - binding '1' to parameter: 1
DEBUG hibernate.jdbc.AbstractBatcher - about to open ResultSet (open ResultSets: 0, globally: 0)
DEBUG hibernate.loader.Loader - processing result set
DEBUG hibernate.loader.Loader - result set row: 0
DEBUG hibernate.loader.Loader - result row: EntityKey[SubChild#1]
DEBUG hibernate.loader.Loader - Initializing object from ResultSet: [SubChild#1]
DEBUG hibernate.persister.BasicEntityPersister - Hydrating entity: [SubChild#1]
DEBUG hibernate.loader.Loader - done processing result set (1 rows)
DEBUG hibernate.jdbc.AbstractBatcher - about to close ResultSet (open ResultSets: 1, globally: 1)
DEBUG hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
DEBUG hibernate.jdbc.AbstractBatcher - closing statement
DEBUG hibernate.loader.Loader - total objects hydrated: 1
DEBUG hibernate.engine.TwoPhaseLoad - resolving associations for [SubChild#1]
DEBUG hibernate.engine.TwoPhaseLoad - done materializing entity [SubChild#1]
DEBUG hibernate.engine.PersistenceContext - initializing non-lazy collections
DEBUG hibernate.event.DefaultDeleteEventListener - deleting a persistent instance
DEBUG hibernate.event.DefaultDeleteEventListener - deleting [SubChild#1]
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.engine.Cascades - done processing cascade ACTION_DELETE for: Child
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.engine.Cascades - done cascade ACTION_DELETE for collection: Parent.childs
DEBUG hibernate.engine.Cascades - deleting orphans for collection: Parent.childs
DEBUG hibernate.engine.Cascades - done deleting orphans for collection: Parent.childs
DEBUG hibernate.engine.Cascades - done processing cascade ACTION_DELETE for: Parent
DEBUG hibernate.impl.SessionImpl - setting cache mode to: NORMAL
DEBUG hibernate.impl.SessionImpl - setting cache mode to: GET
DEBUG hibernate.engine.Cascades - processing cascade ACTION_DELETE for: Parent
DEBUG hibernate.engine.Cascades - done processing cascade ACTION_DELETE for: Parent
DEBUG hibernate.impl.SessionImpl - setting cache mode to: NORMAL
DEBUG hibernate.transaction.JDBCTransaction - commit
DEBUG hibernate.event.AbstractFlushingEventListener - flushing session
DEBUG hibernate.event.AbstractFlushingEventListener - processing flush-time cascades
DEBUG hibernate.event.AbstractFlushingEventListener - dirty checking collections
DEBUG hibernate.event.AbstractFlushingEventListener - Flushing entities and processing referenced collections
DEBUG hibernate.event.AbstractFlushingEventListener - Processing unreferenced collections
DEBUG hibernate.engine.Collections - Collection dereferenced: [Parent.childs#1]
DEBUG hibernate.event.AbstractFlushingEventListener - Scheduling collection removes/(re)creates/updates
DEBUG hibernate.event.AbstractFlushingEventListener - Flushed: 0 insertions, 0 updates, 3 deletions to 3 objects
DEBUG hibernate.event.AbstractFlushingEventListener - Flushed: 0 (re)creations, 0 updates, 1 removals to 1 collections
DEBUG hibernate.pretty.Printer - listing entities:
DEBUG hibernate.pretty.Printer - SubChild{id=1}
DEBUG hibernate.pretty.Printer - Child{subChild=SubChild#1, parent=Parent#1, id=1}
DEBUG hibernate.pretty.Printer - Parent{childs=[Child#1], id=1}
DEBUG hibernate.event.AbstractFlushingEventListener - executing flush
DEBUG hibernate.persister.BasicEntityPersister - Deleting entity: [SubChild#1]
DEBUG hibernate.jdbc.AbstractBatcher - about to open PreparedStatement (open PreparedStatements: 0, globally: 0)
DEBUG org.hibernate.SQL - delete from SubChild where SubChildID=?
DEBUG hibernate.jdbc.AbstractBatcher - preparing statement
DEBUG hibernate.type.IntegerType - binding '1' to parameter: 1
DEBUG hibernate.jdbc.AbstractBatcher - about to close PreparedStatement (open PreparedStatements: 1, globally: 1)
DEBUG hibernate.jdbc.AbstractBatcher - closing statement
DEBUG hibernate.util.JDBCExceptionReporter - could not delete: [SubChild#1] [delete from SubChild where SubChildID=?]
java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC][SQLServer]DELETE statement conflicted with COLUMN REFERENCE constraint 'FK_Child_SubChild'. The conflict occurred in database 'BirdDB', table 'Child', column 'SubChildID'.

So, can anyone comment this issue? Is this a bug or a feature?

As I understand, there is a problem with ordering of DELETE operators.

When I call session.delete(parent), Hibernate processing cascades and sheduled 3 DELETE operators (in this order: DELETE FROM Child, DELETE FROM SubChild, DELETE FROM Parent). However, due on-cascade="cascade" declaration in Parent->Child relation, deleting from Child is not invoked (since deleting of Parent should do this, only later).

Workaround there - removing on-delete="cascade" declaration. Is this the only way?

Seems reasonable to me. Alternatively disable cascade delete on the <many-to-one> to the subchild (cascade delete on a many-to-one is usually semantically wrong anyway...)

Sure, when this relation is used as real many-to-one. But there is a cases, when this relation used as replacement of one-to-one (suggestion of using 'a foreign key with a unique constraint' from reference, section 5.1.11).