title: Spark: persist and repartition order
body: <p>I have the following code:</p>
  
  <pre><code>val data = input.map{... }.persist(StorageLevel.MEMORY_ONLY_SER).repartition(2000)
  </code></pre>
  
  <p>I am wondering what's the difference if I do the repartition first like:</p>
  
  <pre><code>val data = input.map{... }.repartition(2000).persist(StorageLevel.MEMORY_ONLY_SER)
  </code></pre>
  
  <p>Is there a difference in the order of calling reparation and persist? Thanks!</p>