[Hibernate] session and size of PersistentSet

[umrzyk <um...@gm...>]

hi, 

i have a simple ManyToMany relation between profile and and
roles. there are 3 tables: profile(id, name), profile_role(profile_id,
role_id) and role(id, name) and following mapping:

@Entity
@Table(name = "profile")
@SequenceGenerator(name = "PROFILE_SEQ", sequenceName = "profile_id_seq")

class Profile
{
@ManyToMany(cascade = { CascadeType.PERSIST, CascadeType.MERGE }, fetch = FetchType.LAZY)
@Cascade({ org.hibernate.annotations.CascadeType.SAVE_UPDATE })
@JoinTable(name = "profile_role", joinColumns = @JoinColumn(name = "profile_id"), inverseJoinColumns = @JoinColumn(name = "role_id"))
@Sort(type = SortType.COMPARATOR, comparator = Role.class)
public SortedSet<Role> getRoles()
}

here is resulting query:

select PR.profile_id, PR.role_id, R.id, R.name from profile_role PR left outer join role R on PR.role_id=R.id where PR.profile_id=?

it works perfect. well almost, i have just checked session size using
MessAdmin tool and something strange appeared. Profile object is 13 MB
having only one role inside!

Hibernate version is 3.2.2GA. Moreover previously i was using xdoclet
for mappings and above getRoles() property was mapped like this:

	/**
	 * @hibernate.set table="profile_role" cascade="save-update" lazy="true"
	 * @hibernate.collection-key column="profile_id"
	 * @hibernate.collection-many-to-many class="org.model.domain.Role" column="role_id"
	 */
	public Set<Role> getRoles()

which resulted in following queries:

select RP.profile_id, RP.role_id from profile_role RP where RP.profile_id=?
select R.id, R.name from role R where R.id=?

so previous query has been splitted into 2 separate ones, but resulting
object size in session was 14 KB.

Could anyone explain me what is the difference between these two xdoclet
and annotation mappings and why it has so significant impact on
size of resulting PersistenSet ?

thanks,
jm.