I am following the Hibernate documentation for Bidirectional one-to-many with Join tables between Person entity and Address entity and my mapping file is same as the one given in doc:
<class name="Person">
<id name="id" column="personId">
<generator class="native"/>
</id>
<set name="addresses"
table="PersonAddress">
<key column="personId"/>
<many-to-many column="addressId"
unique="true"
class="Address"/>
</set>
</class>
<class name="Address">
<id name="id" column="addressId">
<generator class="native"/>
</id>
<join table="PersonAddress"
inverse="true"
optional="true">
<key column="addressId"/>
<many-to-one name="person"
column="personId"
not-null="true"/>
</join>
</class>
Now when I try to fetch the Person and the corresponding Address's using code:
List<Person> persons = session.createQuery("from Person").list();
for (Person person : persons) {
System.out.println(person);
for (Address address : person.getAddresses()) {
System.out.println(address);
}
}
When the line person.getAddresses() is run then the query generated by hibernate is :
Hibernate: select addresses0_.personId as personId2_1_0_, addresses0_.addressId as addressId1_2_0_, address1_.addressId as addressId1_0_1_, address1_1_.personId as personId2_2_1_
from PersonAddress addresses0_
inner join ADDRESS address1_ // INNER JOIN between PersonAddress & Address
on addresses0_.addressId=address1_.addressId
left outer join PersonAddress address1_1_ // Now LEFT OUTER JOIN with PersonAddress
on address1_.addressId=address1_1_.addressId
where addresses0_.personId=?
If we can get the data using only single LEFT OUTER JOIN between PersonAddress & Address then why Hibernate uses first and INNER JOIN then a LEFT OUTER JOIN? Can some please help me in understanding this.
