title: Azure MongoDB find operation query time is slow
body: <p>I used <code>Robo 3T</code> to test <code>Azure Cosmos MongoDb</code> and Another MongoDb has exactly same data in a VM. </p>
  
  <p>I run very simple query in my local machine (Windows): </p>
  
  <p><code>db.getCollection('PSTN_inspector_wav_data').find({})</code></p>
  
  <p>I can control how many documents I want to get. The result is shown here.</p>
  
  <p>For Azure Cosmos Mongodb:</p>
  
  <ol>
  <li>If I want to fetch 500 documents, it takes 2.135s:
  <a href="https://i.stack.imgur.com/KdNoC.png" rel="nofollow noreferrer">The capture image</a></li>
  <li>If I want to fetch 5000 documents, it takes 18.308s:
  <a href="https://i.stack.imgur.com/7xZWb.png" rel="nofollow noreferrer">The capture image</a></li>
  <li>If I want to fetch 25000 documents, it takes 84.097s:
  <a href="https://i.stack.imgur.com/HC5sG.png" rel="nofollow noreferrer">The capture image</a></li>
  </ol>
  
  <p>For the mongoDb in Vm:</p>
  
  <p>If I want to fetch 25000 documents, it only takes 1.448s
  <a href="https://i.stack.imgur.com/Yuwlf.png" rel="nofollow noreferrer">The capture image</a></p>
  
  <p>It seems for <code>Azure Cosmos Mongodb</code>, the query time has a linear relationship with the documents size.</p>
  
  <p>I already checked the network, it doesn't have any problem.</p>
  
  <p>So can anybody give some guess why it is slow?</p>