title: Is CouchDB per-user database approach feasible for users with lots of shared data?
body: <p>I want to implement a webapp - a feed that integrates data from various sources and displays them to users. A user should only be able to see the feed items that he has permissions to read (e.g. because they belong to a project that he is a member of). However, a feed item might (and will) be visible by many users.</p>
  
  <p>I'd really like to use CouchDB (mainly because of the cool _changes feed and map/reduce views). I was thinking about implementing the app as a pure couchapp, but I'm having trouble with the permissions model. AFAIK, there are no per-document permissions in CouchDB and this is commonly implemented using per-user databases and replication.</p>
  
  <p>But when there is a lot of overlap between what various users see, that would introduce a LOT of overhead...stuff would be replicated all over the place and duplicated in many databases. I like the elegance of this approach, but the massive overhead just feels like a dealbreaker... (Let's say I have 50 users and they all see the same data...).</p>
  
  <p>Any ideas how on that, please? Alternative solution?</p>