Product pages at lunchtime — Architecture trainer

We’re very sorry, but system design is better done on a computer.

Send yourself the link and pick it up at your desk.

Scenario

A shop's product pages each call a product API, which reads the product — name, description, price, stock — from a SQL database. At lunchtime that is 2,000 page loads a second, almost all of them for the same few hundred popular products. A product's price or stock changes a few times a day. Today the database sits at 90% CPU at lunchtime and pages take 800 ms.

Requirements

product pages answer in under 100 ms at lunchtime
the database serves at most 300 reads per second at peak
a changed price shows on the product page within 1 minute
checkout always charges the current price
restarting the cache at lunchtime does not overload the database

Constraints

two engineers, no dedicated ops
one region
the SQL database stays the only source of truth for price and stock

Hints

0/5 requirements ticked