In progress · 24 min
09 · Connection pooling
Why your app dies at 200 concurrent users, and the twelve lines that fix it.
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Eighteen lessons. You are on nine.
Next up · 31 min
10 · Transactions and isolation
Build a booking system, then break it with two people clicking at once.
Locked · 28 min
11 · Indexing for real queries
Read a query plan, add the wrong index on purpose, watch it get slower.
Learn by breaking
Every lesson ends with you causing the failure on purpose, then fixing it. Reading about a deadlock teaches nobody anything.
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- 01
09 · Connection pooling
In progress · 24 minutes
- 02
10 · Transactions and isolation
Next up · 31 minutes
- 03
11 · Indexing for real queries
Locked · 28 minutes
- 04
12 · The N+1 you keep writing
Locked · 19 minutes
- 05
13 · Migrations without downtime
Locked · 34 minutes
- 06
14 · Reading a query plan
Locked · 26 minutes
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“The lesson where they make you cause the deadlock yourself taught me more than a year of reading about them.”
Daniel Okafor
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Do I need to install anything?
No. Each lesson provisions a real database and server in the browser in about four seconds, and throws it away when you leave.
How long is a lesson?
Twenty to thirty-five minutes, and each one ends with something running. You can stop between lessons without losing the thread.
Is the first track really free?
All eighteen lessons, no card and no trial timer. Finish it and then decide whether the rest is worth paying for.
What if I get stuck?
Every lesson has a hint chain and a full solution. Using them is not cheating; getting stuck for an hour teaches nobody anything.
First track is free, all of it.
No card, no trial timer. Finish it and decide whether the rest is worth paying for.
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