Napkin Math #22: turbopuffer, fast search on object storage

July 9, 2024

A little more than a year ago, I started hacking on a new search engine on object storage, starting with vector search: turbopuffer. Today, we’re a full-...

Napkin Math #21: Index Merges vs Composite Indexes in Postgres and MySQ

November 27, 2022

While working with Readwise on optimizing their database, I found myself asking the question: How much faster is a composite index compared to letting the...

Napkin Math #20: Scaling Causal's Spreadsheet Engine from Thousands to Billions of Cells: From Maps to Arrays

July 6, 2022

Earlier this year, I spent a few weeks working with Causal on their core spreadsheet engine. Causal is a spreadsheet built for the 21st century to help...

Napkin Math #19: Metrics For Your Web Application's Dashboards

March 20, 2022

In the beginning of the year I was helping readwise.io get some of their observability up to snuff. A few weeks later "What should I monitor?" came up on...

Napkin Math #18: Neural Net from Scratch

January 3, 2022

Happy new year everyone! In this most recent post, we will establish a mental model for how a neural network works by building one from scratch! In a future...

Careful Trading Complexity for Improvement

November 30, 2021

Whenever you find yourself arguing for improving infrastructure by yanking up complexity, you need to be very careful. Published a new article this morning...

Napkin Problem 16: When To Write a Simulator

September 16, 2021

My rule for when to write a simulator: Simulate anything that involves more than one probability, probabilities over time, or queues. Anything involving...

Napkin Problem 15: Increase Performance by Fitting In the Initial TCP Slow Start Window

July 29, 2021

Did you know that if your site’s under ~12kb the first page will load significantly faster? Servers only send a few packets (typically 10) in the initial...

Napkin Problem 14: Using checksums to verify syncing 100M database records

January 2, 2021

A common problem you’ve almost certainly faced is to sync two datastores. This problem comes up in numerous shapes and forms: Receiving webhooks and writing...

Napkin Problem 13: Filtering with Inverted Indexes

November 8, 2020

Database queries are all about filtering. Whether you’re finding rows with a particular name, within a price-range, or those created within a time-window....

Napkin Problem 12: Recommendations

September 27, 2020

Since last, I sat down with Adam and Jerod from The Changelog podcast to discuss Napkin Math! This ended up yielding quite a few new subscribers, welcome...

Napkin Problem 11: Circuit Breakers

August 22, 2020

You may have heard of a “circuit breaker” in the context of building resilient systems: the art of building reliable systems from unreliable components. But...

Napkin Problem 10: MySQL transactions per second vs fsyncs per second

July 17, 2020

Napkin friends, from near and far, it’s time for another napkin problem! Since the beginning of this newsletter I’ve posed problems for you to try to answer....

Napkin Problem 9

June 7, 2020

Napkin friends, from near and far, it’s time for another napkin problem! As always, consult sirupsen/napkin-math to solve today’s problem, which has all the...

Napkin Problem 8

May 3, 2020

Napkin friends, from near and far, it’s time for another napkin problem! As always, consult sirupsen/napkin-math to solve today’s problem, which has all the...

Napkin Problem 7

April 11, 2020

Napkin friends, from near and far, it’s time for another napkin problem! As always, consult sirupsen/napkin-math to solve today's problem, which has all the...

Napkin Problem 6

March 7, 2020

Napkin friends, from near and far, it’s time for napkin problem number 6! As always, consult sirupsen/napkin-math to solve today’s problem, which has all the...

Napkin Problem 5

February 3, 2020

Napkin friends, from near and far, it’s time for napkin problem number 5! If you are wondering why you’re receiving this email, you likely watched my talk on...

Napkin Problem 4

January 7, 2020

Napkin friends, from near and far, it’s time for napkin problem number four! If you are wondering why you’re receiving this email, you likely watched my talk...

Napkin Problem 3

December 14, 2019

Napkin friends, from near and far, it's time for napkin problem number three! If you are wondering why you're receiving this email, you likely watched my...

Napkin Problem 2

November 1, 2019

Fellow computer-napkin-mathers, it's time for napkin problem #2. The last problem's solution you'll find at the end! I've updated sirupsen/napkin-math with...

Napkin Problem 1

October 18, 2019

Napkin friends around the world: it's time for your very first system' estimation problem! Confused why you're receiving this email? Likely you attended my...