Sampling data with Spark SQL APIs

Often, we need to visualize individual data points to understand the nature of our data. Statisticians use sampling techniques extensively for data analysis. Spark supports both approximate and exact sample generation. Approximate sampling is faster and is often good enough in most cases.

In this section, we will explore Spark SQL APIs used for generating samples. We will work through some examples of generating approximate and exact stratified samples, with and without replacement, using the DataFrame/Dataset API and RDD-based methods.