Can you articulate why you chose SQL over NoSQL, or centralized over distributed caching?

Most guides tell you what to do. Alex Wu tells you what not to do.

For years, one resource has stood head and shoulders above the rest to help engineers navigate this complexity: .

The application checks the cache. On a miss, it reads from the database and updates the cache. (Fast, but risk of stale data). Why Downloading Shady PDFs Breaks Your Preparation

What features are we building? (e.g., Can users post images, or just text?)

If you are looking for the "new" content, you are likely looking for the topics covered in Volume 2 and updated sections of Volume 1, such as: Google Maps (Quadtree/GeoHash) Metrics Monitoring and Alerting Systems Distributed Message Queues S3-like Object Storage How to Effectively Use the "System Design Interview" PDF