title: elasticsearch _update_by_query doesn't work
body: <p>Elasticsearch: 2.3.3</p>
  
  <p>Below are the sequence of my commands</p>
  
  <p>Index a doc</p>
  
  <pre><code>POST test-index/doc
  {
    "name":"sahas"
  }
  </code></pre>
  
  <p>Retrieve the doc</p>
  
  <pre><code>GET test-index/_search
  {
    "query": {
      "match": {
        "name": "sahas"
      }
    }
  }
  </code></pre>
  
  <p>Update the doc</p>
  
  <pre><code>POST test-index/doc/_update_by_query?name=subramanian
  {
    "query": {
      "match": {
        "name": "sahas"
      }
    }
  }
  </code></pre>
  
  <p>Result of update </p>
  
  <pre><code>{
    "took": 9,
    "timed_out": false,
    "total": 1,
    "updated": 1,
    "batches": 1,
    "version_conflicts": 0,
    "noops": 0,
    "retries": 0,
    "failures": []
  }
  </code></pre>
  
  <p>But when I query the document again, its not updated.
  Is there anyway to figure out why update is not working here?
  am i missing something silly?</p>
  
  <p>Appreciate any inputs..</p>