Database TransactionsLearn from verified, runnable examples

Isolation levels, anomalies, locking, MVCC, and real-world concurrency patterns — every claim on this site is proven by code that just ran against a real database.

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Learn PostgreSQL transactions

Learn MySQL transactions

How this site works

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Verified, not vibed

Every session transcript is generated from a real run. CI re-verifies all of them on every change — the site cannot drift from actual database behavior.

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Runnable at home

Clone the repo, `docker compose up`, `bun test`. Every lesson is an executable scenario you can tweak, break, and learn from.

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Built for working devs

You already use transactions. These lessons show you the anomalies hiding in your code — and the patterns that fix them.