Probably the most impactful thing you could learn about when writing efficient SQL is indexing. A very close runner-up, however, is the fact that a lot of SQL clients demand tons of "unnecessary, mandatory work" from the database. Repeat this after me: Unnecessary, Mandatory Work What is "unnecessary, mandatory work"? It's two things (duh): Unnecessary … Continue reading Many SQL Performance Problems Stem from “Unnecessary, Mandatory Work”