Hibernate composite key mapping issue

Question

I'm trying to map entities of the same class (MyData) to each other through a mapping table. MyData has a composite primary key (id1 and id2). When I create the class (see below), it seems like Hibernate is reversing the order of the FK mappings (i.e. a_id1 is pointing to b_id2, etc...). This does not seem right. Does the inverseJoinColumns have to be the opposite order of joinColums? I couldn't find many examples online with composite keys...

public class MyData {
  // has composite key (id1, id2) 

  // ... //

  @ManyToMany
  @Cascade(org.hibernate.annotations.CascadeType.SAVE_UPDATE)
  @JoinTable(name = "MyData_foo", 
    joinColumns = {
      @JoinColumn(name = "a_id1"), 
      @JoinColumn(name = "a_id2") 
    }, 
    inverseJoinColumns = {
      @JoinColumn(name = "b_id1"),
      @JoinColumn(name = "b_id2") })
  )
  private Set<MyData> mySet = new HashSet<MyData>();

  // ... //
}


CREATE TABLE `MyData_foo` (
  `b_id2` bigint(20) NOT NULL default '0',
  `b_id1` bigint(20) NOT NULL default '0',
  `a_id2` bigint(20) NOT NULL default '0',
  `a_id1` bigint(20) NOT NULL default '0',
  PRIMARY KEY  (`a_id1`,`a_id2`,`b_id1`,`b_id2`),
  KEY `FKCD44188BB2B7A1BE` (`b_id1`,`b_id2`),
  KEY `FKCD44188B7997E326` (`a_id1`,`a_id2`),
  CONSTRAINT `FKCD44188B7997E326` FOREIGN KEY (`a_id1`, `a_id2`) REFERENCES `MyData`  (`b_id2`, `b_id1`),
  CONSTRAINT `FKCD44188BB2B7A1BE` FOREIGN KEY (`b_id1`, `b_id2`) REFERENCES `MyData`  (`a_id2`, `a_id1`)
) ENGINE=InnoDB DEFAULT CHARSET=latin1;

Answer 1

Your mapping is wrong. You need to add "referencedColumnName" to all of your JoinColumn annotations, e.g.

@JoinTable(name = "MyData_foo",
 joinColumns = {
  @JoinColumn(name = "a_id1", referencedColumnName = "id1"), 
  @JoinColumn(name = "a_id2", referencedColumnName = "id2") 
}, 
inverseJoinColumns = {
  @JoinColumn(name = "b_id1", referencedColumnName = "id1"),
  @JoinColumn(name = "b_id2", referencedColumnName = "id2")
})
)