title: spark: dataframe.count yields way more rows than printing line by line or show()
body: <p>New to Spark; using Databricks. Really puzzled. </p>
  
  <p>I have this dataFrame: df. </p>
  
  <p><code>df.count()</code> yields Long = 5460</p>
  
  <p>But if I print line by line: 
  <code>df.collect.foreach(println)</code> I get only 541 rows printed out. Similarly, <code>df.show(5460)</code> only shows 1017 rows. What could be the reason?</p>
  
  <p>A related question: how can I save "df" with Databricks? And where does it save to? -- I tried to save before but couldn't find the file afterwards. I load the data by mounting an S3 bucket, if that's relevant. </p>