Foundations of Scalable Systems

Chapter 10. Scalable Database Fundamentals

In the early 2000s, the world of databases was a comparatively calm and straightforward place. There were a few exceptions, but the vast majority of applications were built on relational database technologies. Systems leveraged one of a handful of relational databases from the major vendors, and these still dominate the top ten spots in database market share ranking today.

If you could jump into a time machine and look at a similar ranking from 2001, you’d probably find 7 of the current top 10—all relational databases—in similar places to the ones they occupy in 2022. But if you examine the top 20 in 2022, at least 10 of the current database engines listed did not exist 20 years ago, and most of these are not relational. The market has expanded and diversified.

This chapter is the first of four in Part III that focuses on the data—or persistent storage—tier. I’ll cover the ever-changing and evolving scalable database landscape, including distributed nonrelational and relational approaches, and the fundamental approaches that underpin these technologies.

In this chapter, I’ll explain how traditional relational databases have evolved to adopt distributed architectures to address scalability. I’ll then introduce some of the main characteristics of the new generation of databases that have emerged to natively support distribution. Finally, I’ll describe the architectures utilized for distributing data across multiple database nodes and the ...