title: Map two columns into one on Athena using SerDe properties
body: <p>I'm trying to map two columns into one on Athena using JsonSerDe properties.</p>
  
  <p>In this case, I want to map both columns <code>conversionsRate</code> and <code>cr</code> from jsons 1 and 2 to column <code>cr_new</code> (doing like a coalesce).</p>
  
  <p><em>json1</em></p>
  
  <pre><code>{
    "deviceType": "TABLET",
    "day": "2018-10-27",
    "conversionsRate": 0,
    "clicksCount": 3
  }
  </code></pre>
  
  <p><em>json2</em></p>
  
  <pre><code>{
    "deviceType": "TABLET",
    "day": "2018-10-29",
    "cr": 2,
    "clicksCount": 5
  }
  </code></pre>
  
  <p>The expected result on Athena:</p>
  
  <pre><code>|deviceType|day       |cr_new|clicksCount|
  |TABLET    |2018-10-27|0     |3          |
  |TABLET    |2018-10-29|2     |5          |
  </code></pre>
  
  <p>Is it possible to achieve such a result on athena table mapping using SerDe?</p>