System Design Foundations — How the Pieces Fit Together
A calm summary of system design foundations, showing how core concepts connect into one mental model.
Vivek Molkar
Sharding (How Systems Split Data — and Why It’s Harder Than It Looks)
A first-principles explanation of sharding, why systems split data to scale writes, and the trade-offs that make sharding powerful but dangerous.
Replication (Why Copying Data Improves Resilience — and Introduces Disagreement)
A first-principles explanation of replication, why systems copy data for resilience, and how multiple copies inevitably introduce disagreement.
Read-Heavy vs Write-Heavy Systems (Why Optimizing One Often Hurts the Other)
A first-principles explanation of read-heavy vs write-heavy systems, how workload shapes architecture, and why optimizing one often hurts the other.
Databases vs Caches (Why Some Systems Decide — and Others Just Remember)
A first-principles explanation of databases vs caches, clarifying sources of truth, memory, and why confusing the two leads to fragile systems.
CDN (How Caching Goes Global — and Why Geography Matters)
A first-principles explanation of CDNs, how caching moves closer to users, and why distance and geography still matter on the internet.
Consistency Models (Why Different Users See Different Truths - and Why That’s Sometimes Okay)
A first-principles explanation of consistency models, focusing on agreement over time, real-world trade-offs, and why eventual consistency is often intentional.
Cache Invalidation (Why Making Things Fast Is Easy — Keeping It Correct Is Hard)
A first-principles explanation of cache invalidation, why it is hard, and how correctness quietly breaks in fast systems.
Caching (Why Some Requests Never Reach Your Servers at All)
A first-principles explanation of caching, why it works, where it lives, and why it quietly powers fast systems.
Reverse Proxy (The Silent Middle Layer Most Systems Rely On)
A first-principles explanation of reverse proxies, why they exist, and how they simplify modern system design.