title: What are the advantages of setting "hive.exec.parallel" to false in Hive ?
body: <p>I came to know that when hive.exec.parallel is set to true in hive i.e </p>
  
  <pre><code>set hive.exec.parallel=true;
  </code></pre>
  
  <p>then independent tasks in a query can run in parallel. </p>
  
  <p>Thanks to Qubole for this:
  <img src="https://i.stack.imgur.com/sgwoQ.png" alt="hive parallel execution"></p>
  
  <p>Are there any advantages of setting this parameter to false? 
  I'll iterate myself here: Obviously, whenever possible, you would like to run things in parallel and have more throughput. Why would someone set this parameter to false - are there any disadvantages too? </p>