In this chapter, we introduced you to Spark SQL, SparkSession (primary entry point to Spark SQL), and Spark SQL interfaces (RDDs, DataFrames, and Dataset). We then described some of the internals of Spark SQL, including the Catalyst and Project Tungsten-based optimizations. Finally, we explored how to use Spark SQL in streaming applications and the concept of Structured Streaming. The primary goal of this chapter was to give you an overview of Spark SQL while getting you comfortable with the Spark environment through hands-on sessions (using public Datasets).
In the next chapter, we will get into the details of using Spark SQL to explore structured and semi-structured data typical to big data applications.
