title: Elasticsearch date histogram returning only maximum of 13 buckets
body: <p>I'm trying to run the following query, and expecting 24 buckets to be present but 13 buckets are returned by elasticsearch.</p>
  <pre><code>{
    &quot;query&quot;: {
      &quot;bool&quot;: {
        &quot;must&quot;: [
          {
            &quot;range&quot;: {
              &quot;timestamp&quot;: {
                &quot;gte&quot;: start_time,
                &quot;lte&quot;: start_time + 86400
              }
            }
          },
          {
            &quot;term&quot;: {
              &quot;some_field&quot;: &quot;some_value&quot;
            }
          }
        ]
      }
    },
    &quot;aggs&quot;: {
      &quot;hourly_data&quot;: {
        &quot;date_histogram&quot;: {
          &quot;field&quot;: &quot;timestamp&quot;,
          &quot;fixed_interval&quot;: &quot;60m&quot;,
          &quot;min_doc_count&quot;: 0
        },
        &quot;aggs&quot;: {
          &quot;unique_some_agg_name&quot;: {
            &quot;cardinality&quot;: {
              &quot;field&quot;: &quot;some_other_field&quot;
            }
          }
        }
      }
    },
    &quot;size&quot;: 0
  }
  </code></pre>
  <p>I'm not able figure out how to set the bucket size of data_histogram.</p>