title: Spark Dataframe .does saving the output of an ordered dataframe to a parquet file preserve order
body: <p>if I  create a dataframe from a call to the orderBy method in the Dataframe class. </p>
  
  <p>I then save the result of this dataframe to a  parquet  file.  </p>
  
  <p>Does this write  operation preserve the order of the rows? </p>
  
  <p>I cannot find any documentation that could be present any guarantees . </p>