title: Elastic search date_histogram extended_bounds
body: <p>I want to get date_histogram during specific period, how to restrict the date period? Should I use the extended_bounds parameter? For example : I want to query the date_histogram between '2016-08-01' and '2016-08-31', and the interval is day. I query with this expression : </p>
  
  <pre><code>{
    "aggs": {
      "cf_loan": {
        "date_histogram": {
          "field": "createDate",
          "interval": "day",
          "format": "yyyy-MM-dd",
          "min_doc_count": 0,
          "extended_bounds": {
            "min": "2016-08-01",
            "max": "2016-08-31"
          }
        }
      }
    }
  }
  </code></pre>
  
  <p>But I get the date_histogram not in the range.</p>