Query engines make me feel like a wizard. I cast my incantation: “Give me all the directors and the movies where Arnold Schwarzenegger was a cast member”. Then charges zip through wires, algorithms churn on CPUs, and voila, an answer bubbles up. How do they work? In this essay, we will build a query engine from scratch and find out. In 100 lines of Javascript, we’ll supports joins, indexes, and find our answer for Arnold! Let’s get into it. Choice Our first step is to choose which language we’ll...