title: pymongo method of getting statistics for collection byte usage?
body: <p>The <a href="http://docs.mongodb.org/manual/faq/developers/#how-do-i-optimize-storage-use-for-small-documents">MongoDB Application FAQ mentions</a> that short field names are a technique that can be used for small documents. This led me to thinking, "what's a small document anyway?"</p>
  
  <p>I'm using pymongo, is there any way I can write some python to scan a collection, and get a feel of the ratio of bytes used for field descriptors vs bytes used for actual field data?</p>
  
  <p>I'm tangentially curious on what the basic byte overhead is per doc, as well.</p>