title: Drill Error: UNSUPPORTED_OPERATION ERROR: Only COUNT, MIN and MAX aggregate functions supported for VarChar type
body: <p>below is csv file.</p>
  
  <p>csv file: </p>
  
  <pre><code>STATE,place,populationmales,populationfemales,literatemales,literatefemales
  JAMMU &amp; KASHMIR,Urban,1855942,1558164,1386708,960337
  Kupwara,Rural,418370,357952,245342,148633
  Kupwara,Urban,56756,42486,39055,21046
  </code></pre>
  
  <p>Query:</p>
  
  <pre><code>select `state`,sum(`populationmales`) from dfs.`/Users/ks1162/Documents/pmv.csv` GROUP BY `state`;
  </code></pre>
  
  <p>When i query sum of 'populationmales' which is not a varchar type still getting error  </p>
  
  <p>error:</p>
  
  <pre><code>UNSUPPORTED_OPERATION ERROR: Only COUNT, MIN and MAX aggregate functions supported for VarChar type
  </code></pre>
  
  <p>Below is configuration of csv file in storage plugin:</p>
  
  <pre><code>"csv": {
    "type": "text",
    "extensions": [
      "csv"
    ],
    "extractHeader": true,
    "delimiter": ","
  },
  </code></pre>