title: Understanding mongo db explain
body: <p>I fired a query and tried to explain it on mongo console and got </p>
  
  <pre><code>"isMultiKey" : true,
  "n" : 8,
  "nscannedObjects" : 17272,
  "nscanned" : 17272,
  "nscannedObjectsAllPlans" : 21836,
  "nscannedAllPlans" : 21836,
  "scanAndOrder" : true,
  "indexOnly" : false,
  "nYields" : 0,
  "nChunkSkips" : 0,
  "millis" : 184,
  </code></pre>
  
  <p>Most of the things are explained in <a href="http://www.mongodb.org/display/DOCS/Explain" rel="noreferrer">http://www.mongodb.org/display/DOCS/Explain</a>, but I cannot understand what does nscannedObjectsAllPlans, nscannedAllPlans means. Can anyone help?</p>
  
  <p>Thanks</p>