System Design Classroom

80% Of The Times, Scaling Is Not a Rewrite Problem

How a single interview question reveals who understands load, risk, and trade-offs

Jan 10 • Raul Junco

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December 2025

Happy Teams Build Better Products

6 lessons every engineer eventually learns the hard way.

Dec 12, 2025 • Raul Junco

27

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October 2025

Performance Doesn’t Start at SELECT; It Starts at CREATE.

Stop blaming your queries. Most database slowness comes from design mistakes made on day one.

Oct 28, 2025 • Raul Junco

112

13

8

CDC Isn’t the Shortcut You Think It Is

7 hidden costs of “free” event publishing

Oct 7, 2025 • Raul Junco

50

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September 2025

What Uber’s Slackbot Taught Me About Building Smart AI Assistants

Forget dashboards. The fastest path to insight is an agent that speaks your data’s language.

Sep 30, 2025

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Most Engineers Want Both Consistency and Scalability.

Reality Doesn't Work That Way.

Sep 25, 2025

70

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To Cache or Not to Cache

A 7-question framework for making caching a design decision, not a default.

Sep 16, 2025 • Raul Junco

100

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August 2025

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, 2025 • Raul Junco

85

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July 2025

Retries Have an Evil Twin: Duplicates

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

Jul 28, 2025 • Raul Junco

45

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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, 2025 • Raul Junco

90

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June 2025

High Availability Isn't About Luck

It's About Patterns.

Jun 26, 2025 • Raul Junco

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Distributed Transactions Are the Root of All Complexity

SAGAs provides a structured way to deal with them.

Jun 19, 2025 • Raul Junco

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