You need to use the each() method, not forEach(). forEach() is going to iterate over every document in the batch - as you've discovered this defaults to 101. each() will iterate over every document in the cursor. From the documentation:

each

Iterates over all the documents for this cursor. As with
{cursor.toArray}, not all of the elements will be iterated if this
cursor had been previouly accessed. In that case, {cursor.rewind} can
be used to reset the cursor. However, unlike {cursor.toArray}, the
cursor will only hold a maximum of batch size elements at any given
time if batch size is specified. Otherwise, the caller is responsible
for making sure that the entire result can fit the memory.

http://mongodb.github.io/node-mongodb-native/api-generated/cursor.html

Example code:

// Grab a cursor

      var cursor = collection.find();



      // Execute the each command, triggers for each document

      cursor.each(function(err, item) {



        // If the item is null then the cursor is exhausted/empty and closed

        if(item == null) {



          // Show that the cursor is closed

          cursor.toArray(function(err, items) {

            assert.ok(err != null);



            // Let's close the db

            db.close();

          });

        };

      });