title: Spark custom output path after partition columns
body: <p>In Spark, is it possible to have suffix in the path after partition by columns? </p>
  
  <p>For example:
  I am write the data to the following path:
  /db_name/table_name/dateid=20171009/event_type=TEST/</p>
  
  <pre><code>`dataset.write().partitionBy("event_type").save("/db_name/table_name/dateid=20171009");`
  </code></pre>
  
  <p>Is it possible to create it to the following with dynamic partition?
  /db_name/table_name/dateid=20171009/event_type=TEST/1507764830</p>