Senior Tony

Jul 4, 2024 · Databases

Why MySQL Joins Aren’t Always Slow: Inside the Four Join Algorithms

This article uses a realistic interview scenario to explore why multi-table joins in MySQL are not inherently slow, detailing four join algorithms—simple nested-loop, index nested-loop, block nested-loop, and batched key access—along with their pseudo‑code, execution steps, performance trade‑offs, and the impact of features like MRR and recent optimizer changes.