title: mongodump with query on slave db
body: <p>I'm trying to dump from my secondary so I don't hurt the live traffic.</p>
  
  <p>I can dump from it successfully. but if I add a query I get 0 documents.</p>
  
  <p>What do I need to add to query succesfully to my slave?</p>
  
  <pre><code>0 Documents:
  mongodump --host xxxx --port 27017 --username xxx --password xxx --db test --collection xxxx --query "{date_visited:{'$gte':new Date(1451606400000)}}" --out /dumps/xxxx-after-2016-01-01.json
  
  All Documents:
  mongodump --host xxxx --port 27017 --username xxx --password xxx --db test --collection xxxx --out /dumps/xxxx.json
  </code></pre>