title: Pinot fasthll and distinctcounthll returns different values
body: <p>we are using pinot hll, and got suggested to switch from fasthll to distinctcounthll, but we got the count very different, with the same condition we have 1000x difference.
  Example:</p>
  
  <pre><code>SELECT fasthll(my_hll), distinctcounthll(my_hll)
  FROM counts_table WHERE timestamp &gt;= 1500768000
  </code></pre>
  
  <p>I get results:</p>
  
  <pre><code>"aggregationResults": [
      {
          "function": "fastHLL_my_hll",
          "value": "68685244"
      }, {
          "function": "distinctCountHLL_my_hll",
          "value": "50535"
      }]
  </code></pre>
  
  <p>Could anyone suggest what's the big difference between them?</p>