title: Can MongoDB compress or mark a word that shows up frequently (such as "shopping") as s1 to save space?
body: <p>Say if the app is like Digg, where users post a web link and add tags.  Then there will be many tags that says "shopping", repeatedly in the value part of the key/value pair.</p>
  
  <p>Will MongoDB automatically or be configured so that it will remember that word as "s1" so as to reduce the size of the database?  What if it is the key part that repeat a lot instead (almost always repeat if each "document" has the same property names.)</p>