Hi,

I'm having weird issues trying to use fetch="join" on the properties of more than one subclass of my hibernate mapping file.

First, the situation: I have a constellation of one-to-many tables related by foreign key to a single parent table. The parent table defines the superclass, then overlapping subsets of the related tables define the subclasses. So subclass A will have sets of type (X, Y, and Z) and subclass B will have sets of type (X, V, and W) .

The Hibernate Mapping file looks like this:

The Criteria query used looks like this:


Now, when I execute that Criteria (in order to get both As and Bs back), the select statement output left outer joins V, W, X, Y, and Z (just like you'd think it would). Attempts to access a returned object of type A's properties are successful without Lazy loading (as I want it to be), but any attempt to access an object of type B's properties results in them being lazy loaded, even though they should be available.

But it gets weirder! Which subclass has immediate access to the SELECTed information is position dependent! If I swap subclass B above subclass A in the mapping file, then it works fine, while class A does the lazy loading.

I've also tried moving class A out to an external mapping file, but the behavior is the same, it still insists on lazy loading its properties.

If anybody has seen this before and has a solution, or even has a suggestion about what I should try next, I would be extremely grateful. If I can provide any further information please don't hesitate to let me know. It seems to me that any behavior that treats one sibling differently from another is not working as designed.

Thanks for your time,

matt

I'm not an expert, but I think that all of those fetch=join will result in a cartesian product that will probably cause an OutOfMemoryError, if I understand it correctly.
The size of the number of tuples returned will be M x N x O x P where M,N,O, and P are the sizes of the eager fetched collections. If each collection had only 10 items, that would be 10,000 objects for a single query. Most of that data will be redundant.

You want to use lazy loading when you have that many collection properties.

Thanks for responding, les2. Everyone knows that this isn't the ideal situation, but it's what I have to put up with for a while. All the child tables are pretty sparse, so while it is multiplicative, it's not quite as bad as your example.

I should add to my original post that we're using Hibernate 3.2.5.ga.

Since my first post, I've removed all the 'lazy="false"' references, they don't make a difference in this case and could be distracting from the heart of the issue.

Thanks,

matt