Database

PostgreSQL

The gold-standard open-source relational database.

Official site

Monthly cost

Free

Free to self-host; hosting costs extra

Popularity

5/5

LLM knowledge

5/5

Difficulty

Medium

#open-source#self-hostable

What PostgreSQL is good at

Strengths

+Rock solid
+Rich feature set (JSON, FTS, vectors)
+Huge ecosystem

Tradeoffs

−You manage scaling yourself
−Backups and HA are on you

Coding-agent prompt

Drop into Claude / Cursor to get idiomatic PostgreSQL code.

You're working with PostgreSQL. Follow these rules:

- Parameterized queries only — never string-interpolate user input into SQL.
- Index columns that appear in `WHERE`, `JOIN`, `ORDER BY`. Check `pg_stat_user_tables` to find missing indexes.
- Use `jsonb` (not `json`) for schemaless columns; index with `GIN`.
- Row-Level Security (`ALTER TABLE ... ENABLE ROW LEVEL SECURITY`) for multi-tenant isolation.
- Transactions with `BEGIN; ... COMMIT;` for any multi-statement mutation.
- Use `EXPLAIN ANALYZE` before shipping anything slow.
- Prefer `text` over `varchar(n)` unless you have a hard business constraint on length.

Beginner's guide to PostgreSQL

In one line: A powerful, free database where you store data in tables with rows and columns.

Postgres is a relational database — data lives in tables, like very strict spreadsheets. You query it with SQL (Structured Query Language): 'give me all users who signed up this week'. It's the gold-standard open-source database.

Think of Excel, but built for millions of rows and many users at once.

Try it in your terminal

```
brew install postgresql@16
```
Install Postgres on macOS.
```
psql -d postgres
```
Open the Postgres command-line shell.