[jboss-user] [Persistence, JBoss/CMP, Hibernate, Database] - JBoss CMP loading behavior problem

I am observing, via CMP log records (and poor system performance), unexpected relationship loading behavior by JBoss CMP. No document I've seen has been clear on how CMR works with read-ahead, so I'm not really sure what I should expect. The situation: * JBoss 4.0.2 * Two entities, A and B, with a 1-many relationship from A to B. * Both entities running with the predefined 'Instance per Transaction' container configuration * no CMP optimizations defined, other than the default ones in standardjbosscmp-jdbc.xml: ... <read-ahead> on-load <page-size>1000</page-size> <eager-load-group>*</eager-load-group> </read-ahead> <list-cache-max>1000</list-cache-max> <clean-read-ahead-on-load>false</clean-read-ahead-on-load> ... The problem is with the following simplified code scrap (running in a stateful Session method, within a transaction): 1) A a = ... 2) Collection bs = a.getBs(); 3) Iterator I = bs.iterator(); 4) B b = (B)iterator.next(); 5) System.err.println(b.getFoo()); 6) while (I.hasNext()) 7) System.err.println((I.next()B).getFoo()); 8) System.err.println(b.getFoo()); Everything is fine until line 8. At line 2 I see a relationship load query executed: SELECT OID FROM B where (a=?). At line 5 I see : SELECT OID, foo from B where (OID=?) OR (OID=?) OR ... The number of parameters seems to match the number of Bs that were found at line 2. So this looks like read-ahead to me, even though I've not specified a relationship configuration; perhaps its the default at work? This is evidenced by the the fact that lines 6-7 run without another query being executed. The problem is that at line 8, the same query as in line 5 is reexecuted! It appears that instances loaded within the transaction are discarded by going back and invoking on the first iterated B. This is not what I expect. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4184884#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...