title: Modelling a user ranking system with NoSQL technologies
body: <p>How would you model a system that ranks users based on the row creation date in a world-wide scale? Entries can only be added/removed once a day (as in a batch, for example). And the following requirements/facts must be observed:</p>
  
  <ul>
  <li>No relational database systems can be used</li>
  <li>The response time for a query should be ~ 1 second (a <code>query</code> in a system like this means something like: <code>fetch what's the ranking of user XYZ</code>) </li>
  <li>We're talking about something around 10MM users world-wide</li>
  </ul>