Spark 2.1.0 is released

Apache Spark 2.1.0 was released on Dec 28, 2016. This release mainly focuses on usability, stability, and polish, resolving over 1200 tickets. In this release, Spark SQL has over 580 tickets. The release note only briefly mentions the important features and fixes made in Spark SQL. In the following posts, I will attempt to provide a technical deep dive on the updates of Spark SQL in the 2.1.0 release.