title: Auto compact the deleted space in mongodb?
body: <p>The mongodb document says that</p>
  
  <blockquote>
    <p>To compact this space, run db.repairDatabase() from the mongo shell (note this operation will block and is slow).</p>
  </blockquote>
  
  <p>in <a href="http://www.mongodb.org/display/DOCS/Excessive+Disk+Space">http://www.mongodb.org/display/DOCS/Excessive+Disk+Space</a></p>
  
  <p>I wonder how to make the mongodb free deleted disk space <strong>automatically</strong> ?</p>
  
  <p>p.s. We stored many downloading task in mongodb, up to 20GB, and finished these in half an hour.</p>