If I have a bidirectional 1-M relationship that is lazy.

[1] Order <--> [Many] Requirements

When I retrieve the Order (either though Load or Query), NHibernate issues a SQL query to retrieve the non-lazy properties.

When I iterate over each Requirement in the Order, NHibernate issues a SQL query for the non-lazy properties of a Requirement. However, since Requirement has a backward reference to Order, it also joins all the Order properties in the Query. Why does it do this, since the Order is already loaded in the Session. Is there a way to prevent this.

Thanks,
craig

Do you have outer-join or fetch specified on the Order's Requirement property? You can use an HQL query to override this behavior.

outer-join is true. Are you suggesting set it to false since the parent must be present? What exactly will be the effect of setting outer-join to false in this case?

thanks,
craig

Yes, outer-join is what causes the join since NHibernate doesn't try to deduce whether the parent is or isn't loaded already. If you set it to false, then every time you try to load a child it will just select from the child table and won't add a join to parent. Once again, if you will need to override this in some specific case, you can do so using an HQL or criteria query.

Thanks.

That makes perfect sense and is very helpful advice.

craig