Vol. I · A Postgres Handbook

The Query & the Schema

A reading-room reference for writing PostgreSQL by hand — selects to window functions, with the schema in plain view.

IntermediateAdvanced PostgreSQL

Theory: ACID Properties

The query

SQL
-- Q: Explain ACID in the context of PostgreSQL.
-- Atomicity: "All or nothing" (Transactions either commit fully or rollback).
-- Consistency: Data must adhere to all constraints and rules.
-- Isolation: Concurrent transactions don't interfere with each other.
-- Durability: Committed data is permanently saved even in a crash (via WAL).
Tested against PostgreSQL 16

Note

“PostgreSQL is strictly ACID-compliant by default, unlike some databases that sacrifice it for speed.