https://community.cloudera.com/t5/Support-Questions/Fetch-distinct-values-of-a-column-in-Dataframe-using-Spark/m-p/174631#M136894 <P>Can you share full details of error message?You are probably missing some libraries. If you are reading data from hdfs and running in yarn-cluster mode your parallelism by default will be equal to number of hdfs blocks. As best practice you should avoid doing collect operation unless its small test dataset and instead use saveAsTextFile method to write result dataset to hdfs or local file.</P> Mon, 15 Aug 2016 10:17:45 GMT rreddy 2016-08-15T10:17:45Z