Hi everyone,

Consider the the following (abbreviated) mapping:



The problem that I am encountering is that when I load a node deep in the tree (say a leaf node) hibernate issues enough select stamements to load every node up to the root. For my application this incurs an unacceptable performance hit.

I tried using proxies by adding a attribute to the class tag. The problem with this that even though it avoid loading the parent location nodes, it doesn't load the actual node itself! So something like (pseudocode):


.... later ....



...throws an Exception

because lazily initialized objects cannot be accessed from a session different from the one they were loaded from.

I have also considered using a Set to map the children of each node in hibernate and retrieve the parent with HQL but i am having the same problem of causing exceptions when I access the children from a different session.

I am pretty stuck here and I feel that I have explored all the options provided by the documentation. The advice of someone who has had a similar problem is what I am hoping for.

Thanks in advance,
Giorgos

PS: I am using Hibernate 2.1.2 with MySQL and the Spring Framework

You can force initialize the loaded node by using Hibernate.initialize() or by accessing some of its properties.

Michael,

Thanks for your help.

I would like to ask one more question regarding caching:

What is the effect of using a <cache usage="read-only"> tag for a mutable class? In my mind, and what I would like to achieve, is that when an instance of the specified class is updated it's entry in the cache is simply invalitated. This strategy suits my appliciation as it is mainly read-only (with very few updates).

Thanks again,
Giorgos