I use the Javascript client from Rethink. I write an application to upload files using something similar to sockets. The uploaded files are written into the Rethink database. Besides the file data, I also store some file information.
To get some better performance I separated the server and "worker". To run multiple workers, the NodeJS cluster function is used. The server only manages the file information and has a small API for getting, updating, creating.
The worker listens to all changes that happen in the table where all file information are saved. Every time a new file is inserted, one of the worker starts a listener for the new file on the sockets. When the client sends some file data the worker processes it and simply writes it into the database.