Hibernate version: 1.2.0.2002

Mapping documents:

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

Full stack trace of any exception that occurs:

Name and version of the database you are using: SQL Sever 2005

The generated SQL (show_sql=true):

Debug level Hibernate log excerpt:


Problems with Session and transaction handling? No

We have a mapping document where an association is mapped as follows:

<bag name="Segments" access="field.camelcase-underscore" cascade="all">
<key column="TRIP_ID" />
<one-to-many class="SegmentImpl"/>

An instance of the class containing this collection is loaded. The collection is empty (i.e. it is non-null but has no items). No changes are made and the object is saved. On flushing the session, SessionImpl.IsUpdateNecessary(persister, cannotDirtyCheck, status, dirtyProperties, values, types) returns true, indicating the object is dirty and needs saving. Stepping through this function the visitor that looks at each property finds the bag and gets it's collection entry. The collection entry has a dirty flag set which is why IsUpdateNeccessary returns true.

Can someone explain this? We have a collection that is empty on retrieval and empty on saving so why is it considered dirty?

I have verified that if I comment out the association shown above from the HBM and save no updates occur.

Does that happen during a normal session flush or do you have a detached object that you are reattaching with Update() or SaveOrUpdate() ?

The containing object is transient and has been made persistent through a call to ISession.SaveOrUpdateCopy. The flush mode is "never" so after this call (as part of a decorator chain unwind) an explicit flush is called on the sesssion. It is in the processing of the flush that we see NHibernate detecting the Segments bag as dirty for every domain object existing before the new one was added causing an update to every corresponding row in the database.

A little more information we have after digging further. We have an interceptor that updates a couple of auditing columns in the database. This fires after NHibernate has determined the object is dirty. Subesequently there is code to build a collection of the indexes of the properties that are dirty. What we see is NHibernate only detects the 2 columns the interceptor changed as being dirty. Hence, at one point in the code the Segments bag is considered dirty, in a later part of the code it is not.

Hope this helps. As you can probably infer the problem is our auditing information is getting wiped out whenever a new domain object is added which is a big problem for us.

When you call session.Update() on a transient object, afaik hibernate will always send updates to the db. I think you can prevent that with specifying select-before-update on the class mapping or by using version/timestamp properties.