many-to-many assosiation and performance

Misha_Kan · **Joined:** Tue Jan 04, 2005 5:39 am **Posts:** 37

Hibernate version:3.0.5

Hi,

Here is my model:

Code:

class A {
     Set<B> bs;

     // many-to-many 
     Set<B> getBs() {return bs;}
}

class B {
     Set<A> as

     // many-to-many 
     Set<A> getAs() {return as;}    
}

When I'm calling a.getBs() method hibernate generates the following query:

Code:

select ...
from a_to_b a2b, b 
where a2b.b_id = b.id and 
a2b.a_id = XXX

My problem is: a_to_b table appears first in the from clause. This unbelievably harms Oracle's performance (don't ask why :), its a long story...)

My question are:
1. Can I control the way in which this query is created from code or mappings?
2. If not, can I somehow define to hibernate custom query which will handle this association?
3. If not, what can I do? :)

Thanks a lot!
Michael.

jbosseur · **Posted:** Wed May 31, 2006 2:46 pm

Not sure if this will help to solve your problem but there is a way
to inform a query for loading a collection.... but I think it onlu works
with the session.load(...) method
take a look at:

SQL for loading

Misha_Kan · **Joined:** Tue Jan 04, 2005 5:39 am **Posts:** 37

Thanks!

I looked at the hibernate3.pdf which was probably not finished in 3.0.5 !!! :-)

This part was missing from it!