The first step in using Spark is connecting to a cluster.
In practice, the cluster will be hosted on a remote machine that's connected to all other nodes. There will be one computer, called the master that manages splitting up the data and the computations. The master is connected to the rest of the computers in the cluster, which are called slaves. The master sends the slaves data and calculations to run, and they send their results back to the master.
When you're just getting started with Spark it's simpler to just run a cluster locally. Thus, for this course, instead of connecting to another computer, all computations will be run on DataCamp's servers in a simulated cluster.
Creating the connection is as simple as creating an instance of the
SparkContext class. The class constructor takes a few optional arguments that allow you to specify the attributes of the cluster you're connecting to.
An object holding all these attributes can be created with the
SparkConf() constructor. Take a look at the documentation for all the details!
For the rest of this course you'll have a
sc already available in your workspace.
How do you connect to a Spark cluster from PySpark?