Our stack includes CouchDB consumed in Rails applications. Every time a new developer starts working in it, the first complain is how human thought is designed to create associations everywhere, and how the patterns the mind build are better represented by RDBS.

To them, I just ask them, to let go. Let go all your attachments, let the attachments go into stand alone documents. Stop expecting relationships to be for ever, but embrace them in a nested structure with relevant data. Stop expecting that the world won't change, and drop any idea of implementing schemas in a non RDBS.

Document Based data bases are not best or worst than RDBS, they are a different paradigm, and approach the world in a different way. Somethings are hard, others easier. But it will be impossible if you keep thinking relational while doing non RDBS.