We have been trying to annotate a two column unique constraint onto a table with no success.

The annotation looks like this:

@Entity
@Table( name="mytable",
uniqueConstraints={
@UniqueConstraint(
columnNames={ "MY_COLUMN_1",
"MY_COLUMN_2"
} )
} )
public class MyEntity ...etc

We have the following libraries in the build:
hibernate-core 3.5.6-Final
hibernate-jpa-2.0-api 1.0.0.Final
hibernate-annotations 3.5.6-Final
hibernate-c3p0 3.5.6-Final

And we're running against DB2.

We can build the database successfully from the hibernate annotations, the @Table annotation is being applied (we can use it to change the name of the table) but the unique constraint is never applied and no errors are reported.

It is clearly trying to apply the constraint because if we supply wrong column names an exception is reported.

Any ideas gratefully received.

Hmm ... dogged persistence sometimes pays off. After we set the columns to non-nullable and updated to the versions above and probably did something else the whole thing started working.

May be there's a bug in there somewhere - it would be good to see an exception thrown whenever unique constraints cannot be applied.