I'm using Hibernate 3.1.3

This is a simple class model

public abstract Cat {
private String name;
private int age;
public abstract boolean processAge();
// setter and getter methods
........
}

public BigCat{
public boolean processAge(){
...........
}
}

public LittleCat{
public boolean processAge(){
...........
}
}

(In real enviroment I have about ten subclass)

and a mapping like:

<hibernate-mapping>
<class name="Cat" table="CATS">
<id name="catId" type="long" column="CAT_ID">
<generator class="native"/>
</id>
<discriminator column="internalDiscriminator" type="string"/>
<property name="name"/>
<property name="age"/>

<subclass name="BigCat"/>
<subclass name="LittleCat"/>

</class>
</hibernate-mapping>



It works, but if I try a java statement
List result = getSession().createQuery("BigCat").list();
Hibernate process two select from the table CATS, one for each subclass with internalDiscriminator='BigCat' and internalDiscriminator='LittleCat'.

I find this inefficient and unjustified, how can I perform only one select?

Add polymorphism="explicit" in your mapping file for class element. Read about polymorphic queries in Hibernate reference doc.

Thanks, JayeshJ

I voted your replay