require 'rubygems'
require 'mongo'

uid, aid = BSON::ObjectID.new, BSON::ObjectID.new
db = Mongo::Connection.new.db('testing')
db.drop_collection('ratings')
db.create_collection('ratings')

ratings = db['ratings']
ratings.create_index([[:user_id, Mongo::ASCENDING], [:article_id, Mongo::ASCENDING]], :unique => true)

ratings.save({:user_id => uid, :article_id => aid}, :safe => true)
ratings.save({:user_id => uid, :article_id => aid}, :safe => true)