title: What NoSQL DB should I choose for multi-user project collaboration app?
body: <p>I'm trying to develop <strong>iphone app back-end by PHP or Node.js</strong> (which I haven't decided yet). The app will be like <strong>multi-user project collaboration tool</strong>. For example, each user from iPhone can <strong>create a project</strong> and other <strong>invited members</strong> can discuss <strong>how much</strong> they want <strong>to spend</strong> on this particular project. Each user can <strong>add up single cost</strong> and the <strong>server</strong> will handle the <strong>calculation</strong> of <strong>total expense</strong> and update back to all project members. So it's less likely a real-time app but still, alot of updates record and updates needed to be done by the Database.</p>
  
  <p>As far as I googled...</p>
  
  <p>CouchDB is little bit slower than MongoDB and Radis. </p>
  
  <p>MongoDB is fast but there is a chance to loss old data. Since all data must be persistance for my project, shall I rely on MongoDB?</p>
  
  <p>Radis is much faster than those two, but it's such a over-kill for my project and need to spend more time to learn.</p>
  
  <p>Anyway, I still want to hear from those experienced people from here ... what kind of NoSQL DB is best for my scenario?</p>