Perplexity·Software Engineer·Onsite - System Design / Architecture
Jul 2026
Perplexity system design round for a software engineering role. The core problem was building a timestamped key-value store from scratch with time-travel and rollback, which sounds manageable until you actually have to think through all the edge cases live.
- Design and implement an in-memory key-value store where every operation carries a monotonically increasing timestamp. It must support set, get, delete, a range query over a time interval, and a full-store rollback to any past timestamp. Discuss the data structures you'd use and any assumptions about ties at the same timestamp.
“This is a meaty one.”