title: Distinct on specific column in Hive
body: <p>I am running Hive 071
  I have a table, with mulitple rows, with the same column value
  e.g.</p>
  
  <pre><code> x | y |
  ---------
   1 | 2 |
   1 | 3 |
   1 | 4 |
   2 | 2 |
   3 | 2 |
   3 | 1 |
  </code></pre>
  
  <p>I want to have the x column unique, and remove rows that have the same x val
  e.g.</p>
  
  <pre><code> x | y |
  ---------
   1 | 2 |
   2 | 2 |
   3 | 2 |
  </code></pre>
  
  <p>or</p>
  
  <pre><code> x | y |
  ---------
   1 | 4 |
   2 | 2 |
   3 | 1 |
  </code></pre>
  
  <p>are both good
  as distinct works only on the whole rs in hive, I couldn't find a way to do it</p>
  
  <p>help please
  Tx</p>