title: What is difference between "size" and "storageSize" displayed by Mongo stats() function
body: <p>What is difference between "size" and "storageSize" displayed by Mongo <code>stats()</code> function? Which one shows the actual size on disk for a particular collection? Refer sample data returned by command</p>
  
  <pre><code>db.getCollection('temp_collection').stats()
  
  
  {"ns" : "DB1.temp_collection",
      "count" : 1035219,
      "size" : 1186,
      "avgObjSize" : 1202,
      "storageSize" : 177,
      "capped" : false,
      "wiredTiger" : 
  }
  </code></pre>