gistfile1.js

function incrementalView() { 

  db.changes({
    since: x, 
    onChange: function(doc) {

      // we cant do this, but lets just pretend the map returned 
      // an array of emitted [{key: akey, val: anobj}];
      var viewData = designDoc.map(doc); 

      // Delete all the old stuff relating to this document
      // PROBLEM: this is missing, couchdb without a view engine
      // only has a single index, we can index by the doc._id, or the 
      // view key but not both
      
      // We need an index on the key as that is what is queried
      
      // We need an index on doc._id so that when we get updates / deletions
      // we know to delete the stale view data
      
      // We cant implement our view engine with views, thats crazy
      viewDb.getAll(doc._id, function(docs) {
        docs.forEach(delete);               
      });

      // store the new viewObjects
      viewData.each(function(viewDoc) { 
        var newKey = [viewDoc.key, doc._id];
        viewDb.put(newKey, viewDoc.val);
      });

    }
  });

}

// With the above, queries are simple allDocs queries with a little processing on the way out