Query Performance

Why it got slow — indexes, plans, and the round trips an ORM hides from you.

4 concepts · 160 minutes

• Validation & InjectionNever trust the client — schema validation at the boundary, parameterised queries below it.
• ORMs & Query BuildersConvenience with a leak — you still have to know the SQL it writes for you.
• Indexes & Query PlansWhy one query is 2ms and the identical-looking one is 8 seconds — read the plan.
• The N+1 ProblemOne query becomes 501 — the most common performance bug in application code.