We have a situation where a table, Type1, has multiple composite foriegn keys to other tables but where one of the columns is repeated across those foriegn keys: is this
supported by Hibernate?

<class name=Type1 table="Type1" mutable="true">
<id name="id" column="id" type="java.lang.Integer"/>
<property name="property1" column="property1" />
<property name="property2" column="property2" />
<many-to-one name="foreignKey2" class="Type2">
<column name="property2" />
<column name="property3" />
</many-to-one>
<many-to-one name="foreignKey3" class="Type2">
<column name="property2" />
<column name="property4" />
</many-to-one>
</class>


<class name="Type2" table="Type2" mutable="false" lazy="false">
<composite-id>
<key-property name="property2" column="property2" />
<key-property name="property3" column="property3" />
</composite-id>
<property name="property5" column="property5" />
</class>


<class name="Type3" table="Type3" mutable="false" lazy="false">
<composite-id>
<key-property name="property2" column="property2" />
<key-property name="property4" column="property3" />
</composite-id>
<property name="property6" column="property6" />
</class>

With the above mapping we get the org.hibernate.MappingException
Repeated column in mapping for entity: Type1 column: property2
(should be mapped with insert="false" update="false")

Looks like what we need is the ability to specify a <many-to-one> where we are able to specify the <insert>,<update> attributes
at a <column> level instead of at a <many-to-one> level : that way we can specify the repeated column to be insert=false,update=false
and use insert=true,update=true for the other column.

I realise the same topic has appeared a number of times in the forum : the gist of them seems to me to say that Hibernate does not support having the same column in multiple composite foriegn keys in the same table : is that so or if not what is the solution?

(I am sorry if the solution has already been specified in the forum but if so I seem to be missing it)

Use <formula>property2</formula>

thanks that worked

Gavin's short response suggests he's encountered this problem before, and that he has a baked answer for it. On the other hand, "formula" doesn't seem to have been designed to solve this problem (overlapping keys) -- and since the problem can't be solved with "column", that Hibernate was not designed to solve it.

So, since Hibernate was not designed to manage overlapping keys, can you comment on the potential consequences of using overlapping keys? Is it safe?

To be clear, by overlapping keys I am referring to the example of a column that is included in a composite natural primary key AND one or more composite natural foreign keys.