Clarify requirements and constraints.

Designing location-based systems like Yelp or Facebook's "Nearby Friends".

The book by Alex Xu and Sahn Lam is a highly sought-after resource for software engineers preparing for high-level technical interviews. While the search term "system design interview alex xu volume 2 pdf github upd" often leads users to unofficial repositories or document-sharing sites, the most reliable and updated versions are available through official channels. Core Content of Volume 2