Design a Concurrent, Memory-Bounded Tally Service
Company: Meta
Role: Software Engineer
Category: Software Engineering Fundamentals
Difficulty: medium
Interview Round: Technical Screen
Overview: Design a tally service that records timestamped events and answers inclusive range-count queries, beginning with an exact baseline and evolving toward high concurrency and bounded memory. Discuss retention and accuracy contracts, late events, contention, query performance, overflow, clock assumptions, and durability without assuming infinite exact history.