title: Parallel reducing with Hadoop mapreduce
body: <p>I'm using Hadoop's MapReduce.  I have a a file as an input to the map function, the map function does something (not relevant for the question).  I'd like my reducer to take the map's output and write to two different files. 
  The way I see it (I want an efficient solution), there are two ways in my mind:</p>
  
  <ol>
  <li>1 reducer which will know to identify to different cases and write to 2 different contexts.</li>
  <li>2 parallel reducers, which each one will know to identify his relevant input, ignore the other one's and this way each one will write to a file (each reducer will write to a different file).</li>
  </ol>
  
  <p>I'd prefer the first solution, due to the fact it means I'll go over map's output only once instead of twice parallel - but if the first isn't supported in some way - I'll be glad to hear a solution for the second suggestion. </p>
  
  <p>*Note:  These two final files are supposed to be separated, no need into joining them at this point.</p>