select productdow0_.person as person__, productdow0_.download as download__, productdow0_.download as id0_, productdow0_1_.person as person3_0_, productdow0_.release as release4_0_ from products.downloads productdow0_ inner join public.downloads productdow0_1_ on productdow0_.download=productdow0_1_.id where productdow0_.person=?

public abstract class Download {
  ...
  private Integer id;
  private Person person;
  ...
}

public class ProductDownload extends Download {
  ...
  private Release release;
  ...
}

public class ... extends Download {
  ...
}

<hibernate-mapping>
  <class name="Download" table="downloads" schema="public">
    <id name="id">
      <generator class="sequence">
        <param name="sequence">downloads_id_seq</param>
      </generator>
    </id>
    ...
    <many-to-one name="person" class="Person" />
    ...
    <joined-subclass name="ProductDownload" table="product_downloads" schema="products">
      <key column="download" />
      ...
      <many-to-one name="release" class="Release" />
      ...
    </joined-subclass>
    <joined-subclass name="..." table="..." schema="...">
      <key column="download" />
      ...
    </joined-subclass>
  </class>
</hibernate-mapping>

<hibernate-mapping>
  <class name="Person" table="persons" schema="contacts">
    <id name="id">
      <generator class="sequence">
        <param name="sequence">persons_id_seq</param>
      </generator>
    </id>
    ...
    <property name="name" />
    <property name="email" />
    ...
    [b]<set name="productDownloads" inverse="true">
      <key column="person" />
      <one-to-many class="ProductDownload"  />
    </set>[/b]
  </class>
</hibernate-mapping>

CREATE TABLE public.downloads (
  id serial NOT NULL,
  person integer NOT NULL,
  ...
  PRIMARY KEY (id),
  ...
  FOREIGN KEY (person) REFERENCES contacts.persons (id)
  ...
);

CREATE TABLE products.downloads (
  download integer NOT NULL,
  release integer NOT NULL,
  ...
  PRIMARY KEY (download),
  ...
  FOREIGN KEY (download) REFERENCES public.downloads (id),
  FOREIGN KEY (release) REFERENCES products.product_releases (id)
  ...
);

class Index extends Object {
...
   private Table table;
...
}

class Table extends Object {
...
   private Set indexes;
...
}

class Object {
...
   private Owner owner;
...
}

class Owner {
...
   private Set tables;
...
}

select * from object, table where table.ownerId = ?

select * from object, index where object.tableId = ?

User Table
----------
USER_ID
DATE_CREATED
NAME
ADDRESS_LINE


Item Table
----------
ITEM_ID
DATE_CREATED
NAME

//
// User mapping
//
<hibernate-mapping>
   <class
      name="User" table="USER">
   <id
      name="id" column="USER_ID">
      <generator class="increment"/>
   </id>
   <property
      name="dateCreated" column="DATE_CREATED"/>
   <property
      name="name" column="NAME"/>
   <property
      name="address" column="ADDRESS_LINE"/>
   </class>
</hibernate-mapping>

//
// Item mapping
//
<hibernate-mapping>
   <class
      name="Item" table="ITEM">
   <id
      name="id" column="ITEM_ID">
      <generator class="increment"/>
   </id>
   <property
      name="dateCreated" column="DATE_CREATED"/>
   <property
      name="name" column="NAME"/>
   </class>
</hibernate-mapping>

//
// Class definitions
//
public class Basic_Class
{
   private Long id;
   private Date createdDate;

     // setters
   protected void setId(Long id) { this.id = id; }
   void setCreateDate(Date date) { createdDate = date; }

   // getters
   public Long getId()         { return id; }
   public Date getCreateDate() { return createdDate;  }
}

public class User extends Basic_Class
{
   private String name;
   private String address;

   // setters
   public void setName(String name)    { this.name = name; }
   public void setAddress(String addr) { this.address = addr; }

   // getters
   public String getName()    { return name; }
   public String getAddress() { return address; }
}

public class Item extends Basic_Class
{
   private String name;

   // setters
   public void setName(String name) { this.name = name; }

   // getters
   public String getName()          { return name; }
}