Hibernate doesn't delete master row when subclass is deleted

Question

I have following hibernate mapping and java classes structure:

<class name="A" abstract="true" table="tableA" lazy="false">
        <id name="id" type="long">
            <generator class="native" />
        </id>

        <discriminator column="type" type="string" />       
        <!--common properties-->    

        <subclass name="B" abstract="true" >        
            <join table="tableB">
                <key column="aId"/>             
                <!--subclass common properties-->                                           
            </join> 

            <subclass name="B1" discriminator-value="B1TYPE" >
                <!--subclass properties-->                                  
            </subclass>     

            <subclass name="B2" discriminator-value="B2TYPE" >
                <!--subclass properties-->          
            </subclass>         
    </subclass>         
</class>

 <class name="C" table="tableC">
        <id name="id" type="long">
                <generator class="native" />
            </id>
            <set name="items" cascade="all,delete-orphan">
                <key column="id" not-null="true" />
                <one-to-many class="A" />
            </set> 
     </class>

And java part:

abstract class A
{
}

abstract class B extends A
{
}

class B1 extends B
{
}
class B2 extends B
{
}

class C
{
  Set<A> items;
}

The problem is that there are cases when row deleted from tableB, but is not deleted from tableA. What possible reasons could be for that ?

edit:

When item is removed from class C, and C is stored from its repository class:

C.items.remove(B1);
CRepository.store(C);

Answer 1

The reason is that you have to explicitly define the action on-delete of the tableB foreign key declaration pointing to aId.

By default, this is noaction: this means that when you delete any B entity, the corresponding A related entity is not deleted.

Find more informations on Hibernate documentation, 5.1.11.3. Key

Give a try to this mapping:

<subclass name="B" abstract="true" >        
        <join table="tableB">
            <key column="aId" on-delete="cascade"/>             
            <!--subclass common properties-->                                           
        </join> 

        <subclass name="B1" discriminator-value="B1TYPE" >
            <!--subclass properties-->                                  
        </subclass>     

        <subclass name="B2" discriminator-value="B2TYPE" >
            <!--subclass properties-->          
        </subclass>         
</subclass>