Hibernate version: 2.1.8

Hi everybody! Here is the problem:

I have 5 tables and 5 classes: X, Y, I, G.
They are mapped with "one-to-many" as following:

X --one-to-many--> Y

I --one-to-many--> Y

I --one-to-many--> G

As you can see, there are 2 classes which are pointing to class Y.
In my program, i am loading class Y.
Loading of this class, should cause classes X and I to be loaded.

Now suppose that there is no data in table I, and the field in Y that points on I contains null. In that case there won't be any functional impact, because hibernate will generate OUTER-JOINS.

Those outer-joins will include joins:
1. from Y to X
2. from Y to I
3. from I to G

The problem is: because there is no data in table I, join #2 will retrieve no data, and join #3 will perform FULL TABLE SCAN.

My question is:
How to pervent this from happening?
Why does hibernate generate joins #2 and #3 despite there is null value in the relevant field in class Y?

Thanks a lot!
Michael.

Because when Hibernate does the query, there is no way to know that this field is null.
You should ask your DBA why your DB do a full scan in this case.

when using my hand and make a mapping to X Y I G, I could find only 4 classes and 4 tables. Thus I guess the full scan comes from the hidden table join.

Seriously, I suggest you configure hibernate to print out the generated queries and post them here.

Another guess is that table I is not really empty.