What should I do to define a functional index

http://www.postgresql.org/docs/7.3/inte ... ional.html

in hibernate/xdoclet?

I currently have:

/**
* @hibernate.property
* @hibernate.column
* name="email"
* index="email_address_email_ix"
* length="80"
* not-null="true"
* unique="true"
*/

which generates:

create index email_address_email_ix on email_address (email);

but I want:

create index email_address_email_ix on email_address (lower(email));


What are my options? Is this directly supported? Is there a workaround?

Thanks, Patrick.