title: What vaue to be set for mappers and reducers while executing jobs in hadoop and how to decide it?
body: <p>I am running Hive jobs on hadoop cluster. I just came to know to know that the performance will get improve/change if you just concentrate on different behavior mapper and reducer. But I haven't played with it until. Until no I just played with Hive and executing queries with default mapper and reducer?</p>
  
  <p>As I know about the mapper and reducer I am worried that what value to be set the mapper and reducer so that performance will get vary. I also thinking that is it need to set to master node only or we have to set for all nodes? </p>
  
  <p>Anyone who has idea related to this please explain me scenario about this.</p>
  
  <p>Also what are the other parameters do we need to set while executing jobs?</p>