This document discusses Robert Vandehey's experience moving from C#/.NET to Hadoop/MongoDB at Rovi Corporation. The three main points are: 1) Rovi was experiencing slow ETL and data loading times from their SQL databases into their applications. They implemented a solution using Hadoop to extract, transform, and load the data, and MongoDB to serve the data to applications. 2) Some challenges in the transition included moving the .NET development team to Linux/Java, backwards compatibility for web services, and writes to MongoDB overwhelming disks. 3) Lessons learned include using Hadoop and Pig for as much processing as possible, properly sizing and configuring MongoDB for writes from H