title: Coalesce array of integers in Hive
body: <p><code>foo_ids</code> is an array of type <code>bigint</code>, but the entire array could be null.  If the array is null, I want an empty array instead.</p>
  
  <p>If I do this: <code>COALESCE(foo_ids, ARRAY())</code></p>
  
  <p>I get:
  <code>
  FAILED: SemanticException [Error 10016]: Line 13:45 Argument type mismatch 'ARRAY': The expressions after COALESCE should all have the same type: "array&lt;bigint&gt;" is expected but "array&lt;string&gt;" is found
  </code></p>
  
  <p>If I do this: <code>COALESCE(foo_ids, ARRAY&lt;BIGINT&gt;())</code></p>
  
  <p>I get a syntax error: <code>FAILED: ParseException line 13:59 cannot recognize input near ')' ')' 'AS' in expression specification</code></p>
  
  <p>What's the proper syntax here?</p>