Archive - System Design Classroom

Every repeated LLM call is money on fire

Redis 8 just changed the game with semantic caching that understands meaning, not just keys.

Aug 11 •

July 2025

Retries Have an Evil Twin: Duplicates

Every distributed system has a duplication bug; it just hasn’t been triggered yet.

Jul 28 •

Your Database Doesn't Trust the Server. That's Why It Writes Everything Twice.

What Every Backend Engineer Should Know About Write-Ahead Logs

Jul 9 •

June 2025

High Availability Isn't About Luck

It's About Patterns.

Jun 26 •

Distributed Transactions Are the Root of All Complexity

SAGAs provides a structured way to deal with them.

Jun 19 •

Dead Letter Queues Are Not Your Safety Net

They’re a visibility tool. Most teams misuse them, and lose data silently.

Jun 14 •

You can learn System Design while waiting for your coffee.

A coffee shop operates like a Distributed System; You will learn how below.

Jun 11 •

May 2025

April 2025

What if this happens twice?

The Painful Truth About Retries, Replays, And The Myth Of Perfect Delivery.

Apr 24 •

Why Just Publishing Events Isn’t Enough

Domain Events vs Change Data Capture: The Hard Truth About Using the Right Pattern for the Right Job

Apr 19 •

and

Marcos F. Lobo 🗻🧭

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