Doogal Simpson

I'm a Senior Staff Engineer and former start-up founder. I'm trying to help developers bridge the gap from technical competence to professional engineering.

Joined on Dec 11, 2025 https://doogal.dev/page/links

Doogal Simpson

Mar 18

Why Your Database Hates COUNT(DISTINCT) and Why HyperLogLog is the Cure

#algorithms #probabilisticdatastructures #backendengineering

3 min read

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Doogal Simpson

Mar 18

Stop Joining Millions of Rows for Every Single Swipe

#computerscience #softwareengineering #datastructures

4 min read

Doogal Simpson

Mar 18

How Big Tech Scales View Counts: The Power of HyperLogLog and Harmonic Means

#datastructures #scalability #computerscience

4 min read

Doogal Simpson

Mar 15

How to build a profanity filter that actually works

#softwareengineering #datastructures #algorithms

4 min read

Doogal Simpson

Mar 14

How Docker Actually Works: A Deep Dive into Namespaces and Cgroups

#docker #linux #devops

4 min read

Doogal Simpson

Mar 13

Scaling Profanity Filters: Why I Use Tries for Real-Time Chat

#datastructures #gamedev #algorithms

4 min read

Doogal Simpson

Mar 13

Why Your Linked List Wants to Be a Bloody Tree

#datastructures #algorithms #softwareengineering

4 min read

Doogal Simpson

Mar 11

32-Element Branching: How Scala Vectors Solve Immutable Memory Pressure

#scala #datastructures #functional

4 min read

Doogal Simpson

Mar 11

Why the Ring Buffer is the Foundation of High-Performance Systems

#datastructures #computerscience #performance

4 min read

Doogal Simpson

Mar 9

Your Undo Button is Just a Stack of Pancakes

#datastructures #algorithms #computerscience

4 min read

Doogal Simpson

Mar 8

Why Your Distributed System is a Brawl (and How Queues Fix It)

#architecture #messagequeues #backenddevelopment

3 min read

Doogal Simpson

Mar 7

Why Dynamic Arrays Aren't Actually Dynamic

#datastructures #algorithms #softwareengineering

3 min read

Doogal Simpson

Mar 6

Why removing the Head of Linked List is O(1)

#datastructures #computerscience #algorithms

4 min read

Doogal Simpson

Mar 5

The Pointer Arithmetic of Constant Time: Why Arrays Scale O(1)

#computerscience #datastructures #softwareengineering

4 min read

Doogal Simpson

Mar 4

NASA’s $125M Unit Error: Why Your API Needs Explicit Naming

#softwareengineering #apidesign #backenddevelopment

3 min read

Doogal Simpson

Mar 3

Why Doing Nothing is Mathematically Your Fastest Debugging Tool

#softwareengineering #productivity #problemsolving

4 min read

Doogal Simpson

Mar 2

Why Your Backup Strategy Might Be a $100 Million Gamble

#softwareengineering #devops #sysadmin

4 min read

Doogal Simpson

Jan 26

Clear Tests SCREAM "AAA"! — Arrange, Act, Assert

#beginners #java #testing #webdev

3 min read

Doogal Simpson

Jan 23

Your Comments Are Rotting, So I Hope Your Tests Have A Long Shelf Life

#beginners #webdev #java #programming

3 min read

Doogal Simpson

Jan 21

Stop Letting Third-Party Libraries Hold Your Codebase Hostage

#webdev #beginners #java #programming

3 min read

Doogal Simpson

Jan 19

The Cognitive Budget: How I Write Code I Can Actually Maintain

#beginners #webdev #javascript #programming

3 min read

Doogal Simpson

Jan 16

Silent Failures: The Junior Trap You Need to Avoid

#java #webdev #beginners #cleancode

4 min read

Doogal Simpson

Jan 14

The Law of Loudness: Why Your Code Should Scream, Not Whisper

#webdev #javascript #programming #beginners

4 min read

Doogal Simpson

Jan 5

The 3-Argument Rule: How to Stop "Argument Bankruptcy"

#javascript #beginners #productivity #webdev

3 min read

Doogal Simpson

Jan 2

Don't Let the Domains Touch! The Professional Way to Avoid The Switch Smell

#javascript #beginners #refactoring #webdev

3 min read

Doogal Simpson

Dec 31 '25

The TL;DR Rule: How I Structure Files to Not Annoy My Team

#beginners #javascript #career #programming

3 min read

Doogal Simpson

Dec 29 '25

The "And" Test: How I Spot a Monster Function Before it Bites Me

#beginners #career #javascript #software

3 min read

Doogal Simpson

Dec 26 '25

Stop "Saving Keystrokes". I Spend 3 Seconds to Save 3 Hours

#javascript #career #programming #beginners

3 min read

Doogal Simpson

Dec 24 '25

The Squint Test: How I fix Code that looks like a Grey Brick

#beginners #java #career #webdev

3 min read

Doogal Simpson

Dec 22 '25

Localhost is a Lie: The Happy Path Fallacy

#javascript #java #career #beginners

3 min read

Doogal Simpson

Dec 19 '25

Stop Writing Comments: Why Senior Devs Hate "Stale Lies"

#beginners #cleancode #javascript #career

3 min read

Doogal Simpson

Dec 16 '25

Code is a User Interface (And Yours Might Be Terrible)

#beginners #productivity #career #javascript

3 min read

Doogal Simpson

Dec 11 '25

The Sleep-Deprived Senior Test: Why I Hate Your "Magic Numbers"

#beginners #javascript #codenewbie #career

3 min read

DEV Community

Doogal Simpson

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2 Week Community Wellness Streak

1 Week Community Wellness Streak

Writing Debut

Why Your Database Hates COUNT(DISTINCT) and Why HyperLogLog is the Cure

Want to connect with Doogal Simpson?

Stop Joining Millions of Rows for Every Single Swipe

How Big Tech Scales View Counts: The Power of HyperLogLog and Harmonic Means

How to build a profanity filter that actually works

How Docker Actually Works: A Deep Dive into Namespaces and Cgroups

Scaling Profanity Filters: Why I Use Tries for Real-Time Chat

Why Your Linked List Wants to Be a Bloody Tree

32-Element Branching: How Scala Vectors Solve Immutable Memory Pressure

Why the Ring Buffer is the Foundation of High-Performance Systems

Your Undo Button is Just a Stack of Pancakes

Why Your Distributed System is a Brawl (and How Queues Fix It)

Why Dynamic Arrays Aren't Actually Dynamic

Why removing the Head of Linked List is O(1)

The Pointer Arithmetic of Constant Time: Why Arrays Scale O(1)

NASA’s $125M Unit Error: Why Your API Needs Explicit Naming

Why Doing Nothing is Mathematically Your Fastest Debugging Tool

Why Your Backup Strategy Might Be a $100 Million Gamble

Clear Tests SCREAM "AAA"! — Arrange, Act, Assert

Your Comments Are Rotting, So I Hope Your Tests Have A Long Shelf Life

Stop Letting Third-Party Libraries Hold Your Codebase Hostage

The Cognitive Budget: How I Write Code I Can Actually Maintain

Silent Failures: The Junior Trap You Need to Avoid

The Law of Loudness: Why Your Code Should Scream, Not Whisper

The 3-Argument Rule: How to Stop "Argument Bankruptcy"

Don't Let the Domains Touch! The Professional Way to Avoid The Switch Smell

The TL;DR Rule: How I Structure Files to Not Annoy My Team

The "And" Test: How I Spot a Monster Function Before it Bites Me

Stop "Saving Keystrokes". I Spend 3 Seconds to Save 3 Hours

The Squint Test: How I fix Code that looks like a Grey Brick

Localhost is a Lie: The Happy Path Fallacy

Stop Writing Comments: Why Senior Devs Hate "Stale Lies"

Code is a User Interface (And Yours Might Be Terrible)

The Sleep-Deprived Senior Test: Why I Hate Your "Magic Numbers"