Teiva Harsanyi

The Cold Start Problem: How to Spark Network Effects The cold start problem is a chicken-and-egg trap: no users without value, no value without users.

"The cold start problem is a chicken-and-egg problem: no users without value, no value without users."

read.thecoder.cafe/p/cold-start...

Build Your Own Key-Value Storage Engine—Week 4 Deletes, Tombstones, and Compaction

Build Your Own Key-Value Storage Engine: Week 4 (Written in collaboration with @scylladb.com)
This week, we explore how to handle deletes and compaction in LSM trees.
read.thecoder.cafe/p/build-your...

Build Your Own Key-Value Storage Engine—Week 3 Durability with Write-Ahead Logging

Build Your Own Key-Value Storage Engine—Week 3: Durability with Write-Ahead Logging (Written in collaboration with
@scylladb.com )
This week, we explore how to make data durable with the use of a WAL.
read.thecoder.cafe/p/build-your...

Linus Torvalds vs. Ambiguous Abstractions: When a Helper Function Hides the Intent There’s no issue with abstracting code into a helper function. If we want to optimize for cognitive load, the intent should be as clear as possible, starting with the name.

Linus Torvalds vs. Ambiguous Abstractions
read.thecoder.cafe/p/linus-torv...

Build Your Own Key-Value Storage Engine—Week 2 LSM Tree Foundations

Build Your Own Key-Value Storage Engine—Week 2: In-Memory Store (Written in collaboration with @scylladb.com)

This week, we explore the foundations of LSM trees: memtable and SSTables.
read.thecoder.cafe/p/build-your...

Nothing Beats Kindness: Celebrating World Kindness Day No act of kindness, no matter how small, is ever wasted.

"No act of kindness, no matter how small, is ever wasted."

[New post] Nothing Beats Kindness: Celebrating World Kindness Day 🎉
read.thecoder.cafe/p/nothing-be...

Build Your Own Key-Value Storage Engine—Week 1 In-Memory Store

Build Your Own Key-Value Storage Engine—Week 1: In-Memory Store

The beginning of the series written in collaboration with @scylladb.com where we explore key-value storage engines. This week, we start with a simple in-memory storage and the validation client.
read.thecoder.cafe/p/build-your...

Horror Coding Stories: Therac-25 — A deadly race condition and overflow In total, there were six known radiation overdoses involving the Therac-25,and at least three were fatal.

🎃 Horror Coding Stories: Therac-25—A deadly race condition and overflow
read.thecoder.cafe/p/therac-25

Falsehoods Programmers Believe About Names
www.kalzumeus.com/2010/06/17/f...

[New post]
Speed vs. Velocity: The Difference Between Moving Fast and Moving Forward
read.thecoder.cafe/p/speed-vs-v...

At long last, @chris.blue and I have submitted the final manuscript of Designing Data-Intensive Applications, second edition, to the publisher. There is always more that could be improved but at some point we just have to call it done. Now it goes into production; probably shipping in ~4 months.

I just got my 🇬🇧 visa.

Conflict-Free Replicated Data Types (CRDTs): Convergence Without Coordination No matter when or how often the nodes sync, they always end up with the same state.

[New post]
Conflict-Free Replicated Data Types (CRDTs): Convergence Without Coordination
read.thecoder.cafe/p/crdt

I created a new root website for thecoder.cafe and moved the newsletter to read.thecoder.cafe. Thanks to @Cloudflare, which enabled a smooth transition.

I vibe code the same way I play: saving my progress every 15 seconds.

An image with P99 CONF speakers

P99 CONF is next week! Which talks are on your "can't miss" list?

Agentic Design Patterns Agentic Design Patterns A Hands-On Guide to Building Intelligent Systems, Antonio Gulli Table of Contents - total 424 pages = 1+2+1+1+4+9+103+61+34+114+74+5+4 11 Dedication, 1 page Acknowledgment,...

Agentic Design Patterns
docs.google.com/document/d/1...

The Story of The Coder Cafe: Celebrating the First Year I love sharing, and you give me an audience.

The Story of The Coder Cafe: Celebrating the First Year

This is my story behind the creation of a tech newsletter: the process, the ideas, the struggles, etc.
www.thecoder.cafe/p/the-coder-...

The Coder Cafe book cover.

Today marks the birthday of my newsletter 🥳!

It turns out that I wrote quite a bit during the year, so I decided to compile all the posts and release them as a book (260 pages).

The book is available on Leanpub: DRM-free EPUB/PDF.

Get the book: leanpub.com/thecodercafe...
RT appreciated 🙏.

On-on-one - Teiva Harsanyi

I re-enabled my Calendly session: calendly.com/teiva-harsan...
If you want to chat about tech, non-tech topics, whatever, feel free to book a slot!

Does that help?
- www.vldb.org/pvldb/vol15/...
- cwiki.apache.org/confluence/d...
- cwiki.apache.org/confluence/d...

Organic Growth vs. Controlled Growth: What Kind of Garden Is Your Codebase? A codebase is like a garden: left to grow organically, it becomes colorful but chaotic.

📢 New post: Organic Growth vs. Controlled Growth
What Kind of Garden Is Your Codebase?
www.thecoder.cafe/p/organic-gr...

It explains why, for example, LSM trees achieve low write/update cost but pay in read amplification or memory.

The whitepaper: openproceedings.org/2016/conf/ed...

TIL: The RUM Conjecture

In short, the conjecture says that any access method faces a 3-way trade-off among read overhead, update overhead, and memory/space overhead and you can optimize at most two.

My notes on the SILK: Preventing Latency Spikes in LSM Key-Value Stores whitepaper.

substack.com/@teivah/note...

😁

Sort Lines in Source Code This article was adapted from a Google Tech on the Toilet (TotT) episode. You can download a printer-friendly version of this TotT epis...

Sort Lines in Source Code
testing.googleblog.com/2025/09/sort...

What Makes System Calls Expensive: A Linux Internals Deep Dive An explanation of how Linux handles system calls on x86-64 and why they show up as expensive operations in performance profiles

What Makes System Calls Expensive: A Linux Internals Deep Dive.
blog.codingconfessions.com/p/what-makes...

Another great post by @abhi9u.bsky.social. I learned a lot, including vDSO.

What I Learned During My Paternity Leave: Books, Code, and Fatherhood Life itself is unrepeatable in its details.

📢 New post

What I Learned During My Paternity Leave
Books, Code, and Fatherhood
www.thecoder.cafe/p/paternity-...

Latency and User Experience: How to Minimize Perceived Latency Sometimes, we can’t make things faster, but we can make them feel faster.

I've updated one of my top posts with additional examples from Gmail and Instagram.

Latency and User Experience
www.thecoder.cafe/p/latency-an...