In zend_db 1.x we used reference_map to implements constaints and relations in the data mapper classes. In zend_db 2.0 where should the reference map go?
There is no referencing possible in ZF 2.0
You can see from my previous question that in ZF 2 you'll be either using a full blown ORM like Doctrine 2 or Propel for these kind of purposes or to write your own SQL Queries. The Zend DB Component is seen as a lightweight abstraction to handle simple task related stuff.