Holden Karau is a software development engineer at Databricks and is active in open source. She is the author of an earlier Spark book. Prior to Databricks she worked on a variety of search and classification problems at Google, Foursquare, and Amazon. She graduated from the University of Waterloo with a Bachelors of Mathematics in Computer Science. Outside of software she enjoys playing with fire, welding, and hula hooping.