I don't know why, but NHibernate makes many queries to do unnecessary stuff when flushing the session after e.g. saving one item like:

- getting all lazy collections of objects in memory
- selecting, deleting and inserting again many-to-many data

I never changed these objects, so I don't know why NHibernates thinks they need to be updated with the DB again.

I made a small sample app copying all data access code from there, trying to reproduce it, but there everything went perfect.

I'm really desperate now, because my project, on which I worked for a year is now at stake. So please, if anyone have any suggestions, so please feel free to make them.

Thanks, Rainer.

Can you post your mappings? The cascade settings can be tricky here. If you set cascade of a relation to 'save-update' or 'all', NHibernate follows those relations to determine if there has anything changed, even when you know for sure that nothing has changed in the related objects.

I think the cascading updates are a part of the problem. But two interesting points on that:

When I set all cascadings to "none" and try to save an object, then the many-to-many stuff (Select, Delete, Insert same data again) stops. But in my sample app, I made a similar model, an there I setted the cascading to "all", and none of my problems came.

Second interesting point: although all cascadings are set to "none", at saving NHibernate still gets all lazy collections at flushing.

I can post my mappings, but because there are many classes, I first want to try, if we can isolate the problem.

I finally found the problem and as everyone thought already, it was me :oops: !!! I set the bag fileds in my classes as IList, but the properties as an inherited class of IList which I created. This caused my problems.

Thanks alot for your help.