title: Mongoose.js transactions
body: <p>I know MongoDB doesn't support transactions as relational databases do, but I still wonder how to achieve atomicity for several operations. Hunting around the web, I see people mentioning <a href="http://www.infoq.com/presentations/Transactions-without-Transactions">Transactions without Transactions</a>. Reading through the slides, I am still not clear how to implement that with Mongoose.js.</p>
  
  <p>Take this code snippet for example:</p>
  
  <pre><code>player.save(callback1);
  story.save(callback2);
  </code></pre>
  
  <p>How do I implement callback1 and callback2 so that they either succeed together or fail together?</p>