SchemaExport is not adding 'CASCADE ON ..." when it creates foreign keys during the schema creation. I have a feeling that this is specific to using org.hibernate.dialect.MySQL5InnoDBDialect and the translation between the JPA annotations and the SQL.

With hibernate.hbm2ddl.auto set to 'create' I get the SQL shown in the log below. From what I understand, both foreign key constraints should have 'on delete cascade' at the end of them.

Hibernate Core version: 3.2.2
Hibernate Annotations version: 3.2.1
Hibernate Entity Manager version: 3.2.1

Name and version of the database you are using: MySQL 5.0 InnoDB

The generated SQL (show_sql=true):
15:54:05,387 DEBUG SchemaExport:303 - create table FirstTable (id integer not null auto_increment, primary key (id)) ENGINE=InnoDB
15:54:05,507 DEBUG SchemaExport:303 - create table FirstTable_SecondTable (FirstTable_id integer not null, seconds_id integer not null) ENGINE=InnoDB
15:54:05,627 DEBUG SchemaExport:303 - create table SecondTable (id integer not null auto_increment, primary key (id)) ENGINE=InnoDB
15:54:05,747 DEBUG SchemaExport:303 - alter table FirstTable_SecondTable add index FK95CB7BF97BA45F79 (FirstTable_id), add constraint FK95CB7BF97BA45F79 foreign key (FirstTable_id) references FirstTable (id)
15:54:06,038 DEBUG SchemaExport:303 - alter table FirstTable_SecondTable add index FK95CB7BF91A00BD6 (seconds_id), add constraint FK95CB7BF91A00BD6 foreign key (seconds_id) references SecondTable (id)
15:54:06,298 INFO SchemaExport:196 - schema export complete

The java files:



This does appear to be a bug to me, but I'd like to get some feedback before I file it on JIRA. Any comments/questions are appreciated!

Thanks,
Jim

you probably need to use @OnDelete

and no this is not a bug :-)

Using:
@OnDelete(action=OnDeleteAction.CASCADE)

I get:
org.hibernate.MappingException: only inverse one-to-many associations may use on-delete="cascade":

Apparently this does not work for many-to-many associations. When I delete a row from FirstTable, I would like any rows in FirstTable_SecondTable that reference that row to be deleted. How should I approach this? Do I need explicit code for the link table?

It looks like I have some more reading to do... I just found a note about cascading and ManyToMany on page 24 of the EJB persistence spec, it's a no-no.

What do you think about EntityManager throwing an exception when a cascade annotation is applied to a ManyToMany, instead of just ignoring it?

cascading as defined in the spec has nothing to do with FK cascading, the spec does not define FK cascading actually.

Your problem is different.
A logical @manuToMany cannot combine with @OnDelete, it does not make much sense since other entities might be associated to the target entity

But a
@OneToMany @JoinTable could
Unfortunately, I think Hibernate core will still complain.