Hello

Suppose I have class Parent and a class Child



First I retrieve a Parent from the database with all its children.
I close my session, so now I have 1 Parent with all its children as detached objects.

I now start a second session and only retrieve 1 child. But that child's parent is the same parent I retrived from the first session. So that child is also in the list of children I got from my first DB transaction.

But the problem is: they are both different java instances. So if I change the parent object I got from the first transaction, or I change the child from the second transaction, then I have 2 objects that represent the same row in DB but with different values.

Is there a way to solve/manage these kind of things?

thank you

If you are having two copies of the same data, it is better to go back to your design and see how best you can re-use the data instead of making two DB calls.

thank you for the reply, but I can imagine that that's not always possible

suppose if my second object(Child) that represents data I allready have somewhere in my application was fetched with a query that retrieved ALL Child objects from the DB? So suppose I wanted to retrieve all Child objects from the DB, should I then first check which ones I allready have in my application? and only query the rest of the Child objects? And if yes, what if some properties of child were not loaded on the first time I got my Child object from the DB?

I hope you can still follow me, this thing is bothering me for quite some time now...

hi berndvv

that case is like thread environment? one thread changes one child, second thread makes another changes

both threads have different objects but this objects are same db record, i got it??

now your question is how sync both objects to the database record?

well i read about hibernate caching and concurrence in book Java Persistence (long time ago, sorry) maybe u need read about this topic

regards

Grubhart