04. Databases
Where the data lives. Most modern web apps store users, content, and state in a database. This section covers what databases are, the main families (SQL vs NoSQL), the specific tools I use (Postgres via Supabase), and the patterns and traps that come with each.
Entries
| # | Entry | Status | One-line description |
|---|---|---|---|
| 1 | What is a database? | 🟩 COMPLETE | A persistent, organized store for your app’s data |
| 2 | SQL vs NoSQL | 🟩 COMPLETE | The two main database philosophies and when each fits |
| 3 | SQL — the language | 🟩 COMPLETE | SELECT/INSERT/UPDATE/DELETE and the rest of the basics |
| 4 | Postgres | 🟩 COMPLETE 🟦 LIVING | The world’s most powerful open-source relational database |
| 5 | Supabase | 🟩 COMPLETE 🟦 LIVING | Postgres + auth + storage + APIs, packaged as a service |
| 6 | Schema design | 🟩 COMPLETE | Tables, columns, types — designing them so you don’t regret it |
| 7 | Migrations | 🟩 COMPLETE | Versioned, replayable changes to your database structure |
| 8 | Row-Level Security (RLS) | 🟩 COMPLETE | Per-row access control — Postgres/Supabase’s killer security feature |
| 9 | Indexes & performance | 🟩 COMPLETE | The single biggest lever for speeding up queries |
| 10 | Joins & relationships | 🟩 COMPLETE | How tables connect to each other — one-to-many, many-to-many, etc. |
| 11 | Transactions & ACID | 🟩 COMPLETE | All-or-nothing operations — why your bank loves them |
Suggested reading order
1 → 2 → 3 → 4 → 5 → 6 → 8 → 7 → 10 → 9 → 11. If you only read three, read 1, 5, and 8 — Supabase + RLS is the day-to-day reality.
See also
- 03. Backend — what usually talks to the database
- 07. Security & auth — auth and RLS are deeply intertwined
- Gotchas — Supabase