The Coder Cafe | Teiva Harsanyi | Substack

Welcome to The Coder Cafe!

AI is getting better every day. Are you? At The Coder Cafe, we serve fundamental concepts to make you an engineer that AI won't replace.

Nov 3, 2024 • Teiva Harsanyi

Most Popular

Working on Complex Systems

May 7, 2025 • Teiva Harsanyi

So, I Wrote a Book

Apr 8, 2025 • Teiva Harsanyi

Unit Tests As Documentation

Oct 17, 2024 • Teiva Harsanyi

How Linux 7.0 Broke PostgreSQL

Apr 29 • Teiva Harsanyi

Recent posts

Services in Space

From a disastrous job interview to building service architecture for spacecraft.

Jun 3 • Teiva Harsanyi

Metastable Failures in Distributed Systems

The system is technically up, effectively down.

May 27 • Teiva Harsanyi

LSM Trees Explained

LSM trees make a deliberate choice: optimize for updates, accept read amplification as the cost.

May 20 • Teiva Harsanyi

The Coder Cafe

The Coder Cafe

AI is getting better every day. Are you? At The Coder Cafe, we serve fundamental concepts to make you an engineer that AI won't replace. Written by a Google SWE, trusted by thousands of engineers worldwide.

The latest from

Teiva Harsanyi

Services in Space

Concepts

Metastable Failures in Distributed Systems

The system is technically up, effectively down.

May 27 • Teiva Harsanyi

LSM Trees Explained

LSM trees make a deliberate choice: optimize for updates, accept read amplification as the cost.

May 20 • Teiva Harsanyi

AI for Production

Active incidents can be cognitively brutal.

May 13 • Teiva Harsanyi

Cache Use Cases Explained

The cache didn't change. The code didn't change. The system grew around the cache, and the cache quietly became load-bearing.

May 6 • Teiva Harsanyi

How Linux 7.0 Broke PostgreSQL

Linux 7.0 delivered roughly half the throughput of Linux 6.x on the same hardware and workload.

Apr 29 • Teiva Harsanyi

Systems Thinking Explained

Your system isn't broken because of bad engineering. It's broken because you're reacting to events without seeing the structure that produces them.

Apr 22 • Teiva Harsanyi

How an SSD Works

Your SSD doesn't just store data, it relies on quantum physics to do it.

Apr 15 • Teiva Harsanyi

Working on Complex Systems

My Talk at the Monster SCALE Summit 2026

Mar 24 • Teiva Harsanyi

3 Bullets and a Call to Action

When communicating via email or chat, people prefer short and memorable messages that do not require too much cognitive effort to process.

Mar 18 • Teiva Harsanyi

Categories

Distributed Systems

Lattes & Stories

Services in Space

From a disastrous job interview to building service architecture for spacecraft.

Jun 3 • Teiva Harsanyi

The Story of The Coder Cafe

I love sharing, and you give me an audience.

Oct 9, 2025 • Teiva Harsanyi

What I Learned During My Paternity Leave

Life itself is unrepeatable in its details.

Sep 16, 2025 • Teiva Harsanyi

Why I Switched to Vim Keybindings

After switching to Vim keybindings, I found I was not only consistent in my editing but faster than ever.

Jul 24, 2025 • Teiva Harsanyi

The Coding Corner

Build Your Own Key-Value Storage Engine—Week 8

Mar 11 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 7

Block-Based SSTables and Indexing

Feb 26 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 6

Block-Based SSTables and Indexing

Jan 21 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 5

Leveling and Key-Range Partitioning

Jan 14 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 4

Deletes, Tombstones, and Compaction

Dec 17, 2025 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 3

Durability with Write-Ahead Logging

Dec 3, 2025 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 2

LSM Tree Foundations

Nov 19, 2025 • Teiva Harsanyi

Build Your Own Key-Value Storage Engine—Week 1

In-Memory Store

Nov 5, 2025 • Teiva Harsanyi

Announcements

The Reading Room is Open

And You're Invited

Apr 24 • Teiva Harsanyi

🎉 1,000 Subscribers, 1 Coding Challenge!

We just hit a big milestone at The Coder Cafe! To celebrate, we’re launching our own Discord server and kicking off a coding challenge with prizes.

Apr 23, 2025 • Teiva Harsanyi

The Coder Cafe: Learn One Concept With Your Coffee

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