In Week 2 , I shifted focus from high-level scalability concepts to how data is actually stored, retrieved, and optimized in real systems.

The main goals this week were to:

Build intuition around storage engines and access patterns

Understand SQL vs NoSQL trade-offs

Learn where indexes and caching fit into system design

Apply these ideas by designing and implementing a User Profile Service

Compared to Week 1, this week went deeper into backend fundamentals—and required slowing down to truly understand what happens under the hood.

Key Learnings from Designing Data-Intensive Applications — Chapter 3

Chapter 3 (Storage & Retrieval) was significantly more challenging than earlier chapters—but also much more rewarding.

Storage Engines: Why Data Layout Matters

One of the biggest takeaways was that databases are not magic .…