title: MongoDB: sorted arrays
body: <p>Consider the following MongoDB document:</p>
  
  <pre><code>SomeObject {
      nested_objects_ids : [
          ObjectId( "1..." ), 
          ObjectId( "2..." ),
          ...
          ObjectId( "N..." )
      ]
  }
  </code></pre>
  
  <p>The length of <code>nested_object_ids</code> is not limited.
  Is there an elegant way to keep the <code>nested_object_ids</code> array sorted after pushing arbitrary values (i.e. ObjectIds)? </p>
  
  <p>Thank you!</p>