PostgreSQL Query Rewriting Techniques The previous articles in this series covered performance problems you fix by adding indexes, restructuring joins, or tuning memory. This one is about the queries where the plan is "fine" — every node is doing something reasonable — but the query itself is asking the wrong question, producing unnecessarily large intermediate results or forcing the planner dow
This section is the map for the rest of the book. The five stages introduced in the 1.1 chapter overview (parse, analyze/rewrite, plan, portal, execute) are traced here through the actual code: which functions implement each stage, and in what order they get called. The mechanics of each of the five stages are unpacked in later chapters. Here, only the skeleton matters: how a backend starts up, ho
PostgreSQL Internals · Chapter 1 Query Processing Suppose a client sends SELECT * FROM users WHERE id = 1. The path that single line travels before coming back as a result row is longer than you might expect. Inside the PostgreSQL backend, that SQL goes through a five-stage pipeline. Backend entry and dispatch. The backend receives the message from the client and decides which processing path it s
Il y a quelques années, au lycée (entre 2022 et 2025), un professeur m'a donné le déclic pour l'informatique. Je passais mes journées sur des forums à décortiquer le fonctionnement des réseaux et de la sécurité. Mais j'ai vite été frappé par une réalité : apprendre la tech aujourd'hui demande souvent de "donner un organe". Il faut une connexion fibre, un abonnement coûteux, et surtout, on laisse s
SQL is widely known for data querying and manipulation but systems do grow; data becomes larger; processes become repetitive and operations become sensitive. SQL has some features which enables it to be considered a fully fledged programming language. Some of the features which I discuss in this article are procedures, functions and transactions. Each of these concepts serve distinct purposes. Sto
Introduction Placing RDS in a private subnet protects it from unauthorized external access — but it also means you can no longer connect directly from your developer machine. This article walks you through a step-by-step guide to securely connect to a private-subnet RDS (PostgreSQL) instance using AWS Client VPN. Developer PC │ │ UDP 443 (TLS / Mutual Certificate Authentication) ▼ Client
A correct JWT verifier does eight things. Most production verifiers I have read do four or five of them. The other three or four get skipped because the library defaults aren't loud about them, the docs gloss over them, or someone copied a "it works" snippet from Stack Overflow circa 2018. Here is the full eight-check list, what each one prevents, and what it looks like to implement them with stru
Billing code is the most dangerous place to have subtle bugs. It rarely crashes — it just silently does the wrong thing. Here are two we found and fixed in ClipCrafter, an AI video clip extraction tool. We track how many seconds of video each user processes per day to enforce plan limits. The original increment looked like this: const { data } = await db .from("users") .select("daily_usage_sec