title: AWS Athena (Presto with JsonSerde) fails quietly on some Column Names, which ones are acceptable?
body: <p>I tried creating this simple table in Athena:</p>
  
  <pre><code>CREATE EXTERNAL TABLE ctc.rets (
    `SystemID` string,
    `blah` string
  ) 
  ROW FORMAT SERDE 'org.openx.data.jsonserde.JsonSerDe'
  WITH SERDEPROPERTIES (
    'mapping.SystemID' = 'L_ListingID',
    'mapping.blah' = 'Ext_Char10_11' 
  ) 
  LOCATION 's3://xyz.bucket/mydata/'
  TBLPROPERTIES ('has_encrypted_data'='false');
  </code></pre>
  
  <p>The field named <code>blah</code> maps fine, but the field named <code>SystemID</code> comes up blank on every row.</p>
  
  <p>And then it gets really interesting:</p>
  
  <ul>
  <li>I change the <code>SystemID</code> field name to <code>WTF</code>, or <code>foobar</code>, or <code>strawberry</code>, and <strong>it works fine</strong> (the data shows up).</li>
  <li>I change the <code>SystemID</code> field name to <code>_SystemID</code>, <code>f_SystemID</code>, <code>ystemID</code>, <code>System_I_D</code>, and <strong>none of them work</strong></li>
  </ul>
  
  <p>There is never an error message.</p>
  
  <p>What are the actual rules that need to be followed for the field names?</p>