title: mongodb aggregation php
body: <p>I'm using mongodb 2.1 and how to translate this query into php </p>
  
  <pre><code>db.counter.aggregate([ 
   { $match:{ page_id:123456 }}, 
   { $group:{_id:"$page_id",total:{$sum:"$pageview"}} } 
   ]);
  </code></pre>
  
  <p>Thanks</p>