title: HiveQL: Merge array columns
body: <p>I have a table with columns having arrays, how to write HiveQL to merge the array columns?</p>
  
  <pre><code>| id | colA             | colB            | colC 
  +----+------------------+-----------------+------------------    
  | 1  | ["john", "james"]| ["peter"]       | ["sam","peter"]
  | 2  | ["jane"]         | ["doug"]        | ["mary","peter"]
  | 3  | ["jan", "james"] | ["peter","mary"]| ["sam","peter"]
  </code></pre>
  
  <p>Write query to display data like this:</p>
  
  <pre><code>| id | newcol
  +----+------------------------------------------------------    
  | 1  | ["john", "james", "peter", "sam","peter"]
  | 2  | ["jane", "doug", "mary","peter"]
  | 3  | ["jan", "james", "peter","mary","sam","peter"]
  </code></pre>