AnthropicVerified interview challenge
TTL database bug hunt
Review an in-memory key-value store and find where its expiry behaviour breaks the contract.
Unlock with Full AccessThe challenge
Values in the store can expire, be replaced or be deleted. Read the implementation and identify the faults that make its operations disagree about whether a value is still available. Explain the effect of each bug and how you would fix it.
What you'll practise
Time-based behaviour
Check how the store behaves as values reach their expiry time.
Consistent operations
Follow the state changes across reads, writes, scans and deletes.
Explaining a fix
Connect each fault to its consequence and a focused correction.
TTL store implementationCode included in the full challenge
Your diagnosis
Explain the expiry faults and how you would fix them.
The code, instructions and feedback are included with Full Access.