how to avoid duplicate constraints in mysql table

[javatwo]

Hi, we are using Mysql 5.x and JBoss 5.1.0.

We stop/start JBoss often, and found duplicate constraints, for example,

mysql> show create table Book

CONSTRAINT `FK61687183494D1F9` FOREIGN KEY (`userId`) REFERENCES `user` (`id`),
CONSTRAINT `FK61687183494DD3C` FOREIGN KEY (`userId`) REFERENCES `user` (`id`),
CONSTRAINT `FK61687183494E0FD` FOREIGN KEY (`userId`) REFERENCES `user` (`id`),

This will harm mysql performance.

How to prevent Hibernate from generating duplicate constraints? Thanks.
Dave

[wdfink]

Do you know to which table the CONSTRAINT is linked?

Also how your entity is annotated and how the deployment descriptor looks like?

- create / remove table by deploy

- anntotation of relation

[javatwo]

public class Merchandise {

@ManyToOne
@JoinColumn(name="unit")
public Unit getUnit() {
  return unit;
}

}

public class Unit {

...  

}

show create table Merchandise

CONSTRAINT `FK859C7BA3FBCB8305` FOREIGN KEY (`unit`) REFERENCES `unit` (`id`),
CONSTRAINT `FK859C7BA3FBCB8307` FOREIGN KEY (`unit`) REFERENCES `unit` (`id`)

Hibernate:　set "hibernate.hbm2ddl.auto" to "update".

How to tell Hibernate not to create such duplicate FOREIGN KEY constraints.  Thanks for help.

Dave