Backend and databases
PHP, Laravel, SQL, API design, queues and caching — what decides whether a site survives its second thousand customers.
3
Easy
2
Medium
2
Hard
Tests in this topic
2 tests at the “Hard” level. Clear the filter to see the whole topic.
Indexes, transactions and locking
Twelve questions for people who already design schemas and read query plans: selectivity, column order in a composite index, covering indexes, EXPLAIN, isolation levels, deadlocks and what an index costs on writes. The last question is open and reviewed by a human.
- Questions in the test
- 12 questions
- Time limit
- 12 min
Queues, caching and scaling
Twelve questions about what breaks once a service stops being a single process: handler idempotency, retries and dead letter, cache invalidation and cache stampede, in-process state across replicas, health checks and graceful shutdown. Hard level, for people who have already fixed this in production. The last question is open and reviewed by a human.
- Questions in the test
- 12 questions
- Time limit
- 12 min