System design · Fundamentals
3 conversations.
medium free ✓ reviewed
Consistent hashing solves a problem you have to feel to understand
Add one server to a naive hash-mod-N cache and almost every key moves. Consistent hashing exists to make "almost every" become "almost none."
32 turns · 2 traps · read → hard ✓ reviewed
Rate limiting, and why the counter you'd reach for first is broken
The obvious "count requests per minute" quietly lets through double the limit at the worst possible moment. The fix is a bucket that thinks in refill rate, not windows.
32 turns · 2 traps · read → medium free ✓ reviewed
A URL shortener is a lookup problem wearing an algorithm costume
Everyone reaches for a clever hash. The interview is really testing whether you notice this is a read-heavy key-value problem, not a puzzle.
34 turns · 2 traps · read →