E-commerce Inventory Design: Concurrency Control

Problem Overview

Design an e-commerce system that supports two core operations: (1) query availability — allow users to check whether items are in stock, and (2) place order — allow users to purchase items. The design must address data contention problems that arise under concurrent usage (e.g., multiple users trying to buy…

• 1 candidate-reported follow-up — the exact probes interviewers asked, with the trigger for each
• The rest of the problem statement — full requirements, constraints, and edge cases
• Approach and trade-offs — what passing candidates did, and the mistakes that sink people