Eclipse Community Forums
Forum Search:

Search      Help    Register    Login    Home
Home » Eclipse Projects » EclipseLink » Table is referenced twice (due to inheritance?)
Table is referenced twice (due to inheritance?) [message #1011034] Mon, 18 February 2013 17:47
Marian Seitner is currently offline Marian SeitnerFriend
Messages: 5
Registered: August 2010
Junior Member
Hi!

I have the following set of entities:

// Customer, Channel //

@Entity
@SequenceGenerator(name = "CUSTOMER_SEQ", sequenceName = "CUSTOMER_SEQ")
public final class Customer {

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "CUSTOMER_SEQ")
  private int	id;

}

@Entity
@SequenceGenerator(name = "CHANNEL_SEQ", sequenceName = "CHANNEL_SEQ")
public final class Channel {

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "CHANNEL_SEQ")
  private int					id;

  @ManyToOne
  @JoinColumn(name = "customer_id")
  private final Customer		customer;

}

// Subject hierarchy //

@Entity
@Inheritance
@DiscriminatorColumn(name = "SUBJECT_TYPE", length = 1)
@SequenceGenerator(name = "SUBJECT_SEQ", sequenceName = "SUBJECT_SEQ")
public abstract class Subject implements Serializable {

  @Id
  @GeneratedValue(strategy = SEQUENCE, generator = "SUBJECT_SEQ")
  private int					id;

}

@Entity
@DiscriminatorValue("U")
public class User extends Subject {
	
  ...
	
}

@Entity
@DiscriminatorValue("S")
public class Server extends Subject {
  
  ...
  
}

// RoleAssignment hierarchy //

@Entity
@Inheritance
@DiscriminatorColumn(name = "ASSIGNMENT_TYPE", length = 2)
@SequenceGenerator(name = "ROLE_ASSIGNMENT_SEQ", sequenceName = "ROLE_ASSIGNMENT_SEQ")
public abstract class RoleAssignment {

  @Id
  @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "ROLE_ASSIGNMENT_SEQ")
  private int				id;

  @ManyToOne
  @JoinColumn(name = "subject_id", referencedColumnName = "id")
  private final Subject	subject;

  @ManyToOne
  @JoinColumn(name = "role_id", referencedColumnName = "id")
  private final Role		role;
  
}

@Entity
@DiscriminatorValue("CU")
public final class CustomerRoleAssignment extends RoleAssignment {

  @ManyToOne
  @JoinColumn(name = "customer_id", referencedColumnName = "id")
  private final Customer	customer;
  
}

@Entity
@DiscriminatorValue("CH")
public final class ChannelRoleAssignment extends RoleAssignment {

  @ManyToOne
  @JoinColumn(name = "channel_id", referencedColumnName = "id")
  @QueryInit("customer")
  private final Channel	channel;
  
}


... and this JPQL query:

select distinct user from User user
inner join ChannelRoleAssignment channelRoleAssignment on channelRoleAssignment.subject.id = user.id
where channelRoleAssignment.channel.customer = ?1


While it returns the desired result the generated SQL query references the subject table twice:

SELECT DISTINCT t2.ID, t2.SUBJECT_TYPE, t2.EMAIL, t2.FIRSTNAME, t2.LASTNAME, t2.TYPE, t2.customer_id
FROM SUBJECT t3, SUBJECT t2, CHANNEL t1, ROLEASSIGNMENT t0 
WHERE (((t1.customer_id = ?) AND (t2.SUBJECT_TYPE = ?)) AND ((((t3.ID = t0.subject_id) AND (t3.ID = t2.ID)) AND (t0.ASSIGNMENT_TYPE = ?)) AND (t1.ID = t0.channel_id)))

bind => [1, U, CH]


The subject table is already explicitly included via "from User user" so there's no need to join it again. I would expect the following query, which returns the exact same result:

SELECT DISTINCT t2.ID, t2.SUBJECT_TYPE, t2.EMAIL, t2.FIRSTNAME, t2.LASTNAME, t2.TYPE, t2.customer_id
FROM SUBJECT t2, CHANNEL t1, ROLEASSIGNMENT t0
WHERE (((t1.customer_id = ?) AND (t2.SUBJECT_TYPE = ?)) AND (((t2.ID = t0.subject_id) AND (t0.ASSIGNMENT_TYPE = ?)) AND (t1.ID = t0.channel_id)))


Can anybody explain why this happens or how to avoid it?


Thanks,
Marian
Previous Topic:DynamicEntities performance
Next Topic:EclipseLink Download Error
Goto Forum:
  


Current Time: Sat Nov 29 07:44:32 GMT 2014

Powered by FUDForum. Page generated in 0.01619 seconds
.:: Contact :: Home ::.

Powered by: FUDforum 3.0.2.
Copyright ©2001-2010 FUDforum Bulletin Board Software