Fetching data only for specified mapping in HQL query

Question

I have following hbm.xml file

    <hibernate-mapping>
      <class catalog="test_user" name="test.user" table="user">
        <id name="id" type="java.lang.Long">
          <column name="id"/>
          <generator class="identity"/>
        </id>
        <property name="name" type="string">
          <column length="200" name="name" unique="true"/>
        </property>

    <set fetch="join" inverse="true" lazy="true" name="education" table="user_education">
          <key>
            <column name="aid"/>
          </key>
          <one-to-many class="test.UserEducation"/>
        </set>
<set fetch="join" inverse="true" lazy="true" name="employment" table="user_employment">
          <key>
            <column name="aid"/>
          </key>
          <one-to-many class="test.UserEmployment"/>
        </set>
<set fetch="join" inverse="true" lazy="false" name="otherProfiles" table="user_other_profile">
          <key>
            <column name="aid"/>
          </key>
          <one-to-many class="test.OtherProfile"/>
        </set>
<set fetch="join" inverse="true" lazy="false" name="settings" table="user_setting">
          <key>
            <column name="aid"/>
          </key>
          <one-to-many class="test.Setting"/>
        </set>
<set fetch="join" inverse="true" lazy="false" name="images" table="user_images">
          <key>
            <column name="aid"/>
          </key>
          <one-to-many class="test.Images"/>
        </set>
 ..
..
...

and many tables associate with user here I am using fetch="join" for maximum tables. In other queries I have to fetch data from few other related tables so I made fetch="join" .

I want to execute quest

from user as u
left join fetch u.settings
where u.id=25

My problem is when I want to fetch data from user it always fetch data from all associated table where fetch="join" . I want to know how to fetch only related join data. For above query only data from user and settings data should be fetched not from other tables when we have specified fetch="join" for multiple tables.

Answer 1

You should not use fetch="join" because EAGER fetching can lead to Cartesian Products and it's not very efficient .

You need to set those associations to lazy="true" and only fetch themon a query basis:

from user as u
left join fetch u.settings
where u.id=25

This way, you will only fetch Users along with their settings and without join fetching the other associations.