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 paying with fire, welding, and hula hooping. Most recently, Andy Konwinski co-founded Databricks. Before that he was a PhD student and then postdoc in the AMPLab at UC Berkeley, focused on large scale distributed computing and cluster scheduling. He co-created and is a committer on the Apache Mesos project. He also worked with systems engineers and researchers at Google on the design of Omega, their next generation cluster scheduling system. More recently, he developed and led the AMP Camp Big Data Bootcamps and first Spark Summit, and has been contributing to the Spark project. Matei Zaharia is a PhD student in the AMP Lab at UC Berkeley, working on topics in computer systems, cloud computing and big data. He is also a committer on Apache Hadoop and Apache Mesos. At Berkeley, he leads the development of the Spark cluster computing framework, and has also worked on projects including Mesos, the Hadoop Fair Scheduler, Hadoop's straggler detection algorithm, Shark, and multi-resource sharing. Matei got his undergraduate degree at the University of Waterloo in Canada.