[hibernate-dev] Some HQL->SLQ optimizations missing?

At Devoxx some guys are selling a product that compiles some flavor of OQL into SQL and have optimized the case of deep hierarchies mapped as table per subclass (AFAIR). In some case it has quite dramatic effects. They happened to have miscoded their HQL query by using inner joins instead of left outer joins in a few critical places but I don't think that accounts for all optimizations. They do seem to pay careful attention to the list elements returned by the select clause and remove unnecessary joins based on that. Here is their more dramatic example http://fastoql.com/oql_vs_hql.html We might be able to find a couple of optimization to reuse. Emmanuel