Even most toy databases "built in a weekend" can be very stable for years if:

- No edge-case is thrown at them

- No part of the system is stressed ( software modules, OS,firmware, hardware )

- No plug is pulled

Crank the requests to 11 or import a billion rows of data with another billion relations and watch what happens. The main problem isn't the system refusing to serve a request or throwing "No soup for you!" errors, it's data corruption and/or wrong responses.