Finally, polymorphic persistence requires the declaration of each subclass of the root persistent class. For the table-per-class-hierarchy mapping strategy, the <subclass> declaration is used.

<subclass
        name="ClassName"
        discriminator-value="discriminator_value"
        proxy="ProxyInterface"
        lazy="true|false"
        dynamic-update="true|false"
        dynamic-insert="true|false"
        entity-name="EntityName"
        node="element-name"
        extends="SuperclassName">

        <property .... />
        .....
</subclass>

name: The fully qualified class name of the subclass.

discriminator-value (optional - defaults to the class name): A value that distiguishes individual subclasses.

proxy (optional): Specifies a class or interface to use for lazy initializing proxies.

lazy (optional, defaults to true): Setting lazy="false" disables the use of lazy fetching.

Each subclass should declare its own persistent properties and subclasses. <version> and <id> properties are assumed to be inherited from the root class. Each subclass in a heirarchy must define a unique discriminator-value. If none is specified, the fully qualified Java class name is used.

For information about inheritance mappings, see Chapter 9, Inheritance Mapping.