In this section, we'll stop being all high level and hand-wavy and go into a little bit more depth about how Spark works from a technical standpoint. In Spark, under the hood, there's something called the Resilient Distributed Dataset object, which is like a core object that everything in Spark revolves around. Even for the libraries built on top of Spark, such as Spark SQL or MLlib, you're also using RDDs under the hood or extensions to the RDD objects to make it look like something a little bit more structured. If you understand what an RDD is in Spark, you've come ninety per cent of the way to understanding Spark.
Let's talk about the RDD in a reverse order because I'm weird like that. So, fundamentally, the RDD is a dataset, and it is an abstraction for a giant set of data, which is the main thing you need to know as a developer. What you'll do is to set up RDD objects and the RDD will load them up with big datasets and then call...