title: How do i know the size of my mongodb collections so that i can compare that with RAM Size
body: <p>When i googled for MongoDB best pratices , i found out that , the size of collection in mongodb must be smaller when compared to RAM Size of the CPU 
  I have got 6 collections in my mongodb Database .</p>
  
  <p>Please tell me how can i know the size of collections present in MongoDB </p>
  
  <p>The status for one of my collection is </p>
  
  <pre><code>db.chains.stats()
  {
          "ns" : "at.chains",
          "count" : 2967,
          "size" : 89191980,
          "avgObjSize" : 30061.33468149646,
          "storageSize" : 335118080,
          "numExtents" : 18,
          "nindexes" : 3,
          "lastExtentSize" : 67136000,
          "paddingFactor" : 1.0099999999999996,
          "flags" : 1,
          "totalIndexSize" : 34742272,
          "indexSizes" : {
                  "_id_" : 155648,
                  "symbol_1" : 172032,
                  "unique_symbol_1" : 34414592
          },
          "ok" : 1
  }
  </code></pre>
  
  <p>Do i need to sum up the size of all the 6 collections i got and compare that with the RAM Size ??</p>
  
  <p>Or is there any other way ??</p>
  
  <p>Thanks in advance .</p>