What are the FetchType Lazy and Eager?

[woo hwang]

I doo not understand the meaning of LAZY and EAGER exactly.
I have a problem to deploy 2 entities bean with one to many relaionship.
On the one side, default vaule of fetchtype is lazy.
And i have a problem with this message on JBOSS 4.2.1
"org.hibernate.LazyInitializationException: failed to lazily initialize a collection of role: ejb3.Member.spreadsh
eets, no session or session was closed"

If i change the fatchtype to eager on the one side.. another problem is happened
javax.persistence.PersistenceException: org.hibernate.HibernateException: cannot simultaneously fetch multiple bags

|A| 1 ..* |B| 1..* |C|

how should i fix this? and what is exact meaning of fetch?
cheers

[Fernando Ocampo]

For future references with the problem "cannot simultaneously fetch multiple bags" it seems like a hibernate bug. Check these links:

http://lists.jboss.org/pipermail/hibernate-issues/2006-August/000259.html
http://www.jroller.com/eyallupu/entry/hibernate_exception_simultaneously_fetch_multiple

Regards,