LEVEL 8 · BACKEND ENGINEERING

Course Core

Database engineering

Relational databases in depth with PostgreSQL: SQL, modelling and normalisation, indexes and query plans, transactions, isolation and locks, operations, and typing database code.

0 of 5 lessons done

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When you finish, you can

  • Write SQL for any everyday query, including joins and aggregates
  • Model data in tables, normalise it, and denormalise on purpose
  • Read a query plan and add the index that fixes it
  • Choose an isolation level and prevent lost updates and deadlocks
  • Plan migrations, connection pools and backups
  • Type rows, entities and DTOs without confusing them

You build: A normalised, indexed schema for a shop, with migrations and typed repositories

MODULE 1

Design and performance

  1. 1Modelling data for a shopTurn a messy spreadsheet of orders into a normalised PostgreSQL schema for a shop, see each anomaly on real data, add constraints, and walk a category tree.55 min
  2. 2Indexes and query plansRead PostgreSQL query plans, see how a B-tree finds rows, and add composite, partial, expression and covering indexes that make a 100,000-order shop fast again.55 min

MODULE 2

Correctness and operations

  1. 3Transactions, isolation and locksMake a ₦ wallet transfer correct under concurrency with ACID transactions, isolation levels, row locks, deadlock-free ordering and optimistic version checks.60 min
  2. 4Operating databasesRun PostgreSQL behind a live shop: size connection pools, ship migrations with zero downtime, seed safely, restore from backups, and read from replicas.60 min
  3. 5Typing database codeGive database rows honest TypeScript types: nullable columns, entities vs DTOs, typed repositories, generated types, and query builder or ORM trade-offs.55 min

Course checkpoint

Prove you can move on. The checkpoint picks 20 questions at random from every lesson in this course. Get 16 right to pass. Your result is saved in this browser only.