https://blog.cloudera.com/blog/2016/12/achieving-a-300-speedup-in-etl-with-spark/
blog-post-300-percent-etl-speedup-apache-spark#optimal-query-format1 2file dumps, typically in a format like CSV, are regularly uploaded to EDH, where they are then unpacked, transformed into optimal query format, and tucked away in HDFS where various EDH components can use them blog-post-300-percent-etl-speedup-apache-spark#optimal-query-format1 2