hi there,

i have a unidirectional one-to-many relationship "events" from a class user to a class event, i.e. a user has a set of events. but events don't know about user. it's unidirectional because the OO design has a clear dependency check and the event class really doesn't need to know about the user.

now if i want to query events with user information or have constraint based on user attribute, i think i can do this:

from user u, event e where e in elements(u.events) and u.name != 'blah'

since the relationship is unidirectional, i cannot do a more natural one like this: (if there were a bidirectional relationship from event to user as well)

from user u, event e where e.user = u and u.name != 'blah'

my question is the first query looks more expensive than the 2nd one because it's doing a "in", is that right? is there anyway to do something like the 2nd query while keeping the unidirectional relationship? (because i really hate to change the object model just for the sake of better query performance.)

thanks in advance.

you can check the exact sql query executed by turning on sql output.

<property name="hibernate.show_sql">true</property>

That will tell you if the query is much more expensive.

Try this:
from user u inner join u.events e where u.name != 'blah'