Architecture

Correlated Subqueries Explained: From Confusing to Intuitive

Hey everyone! 👋 It's been a while since I posted here. Over the past few days, I've been revisiting SQL from the ground up—not just solving problems, …

Designing Cloud Systems That Accept Temporary Confusion to Handle Massive Load

When thousands of field workers badge into active construction sites at seven in the morning, traditional cloud database designs hit a hard performanc…

The `featured` Column That Cost Us Money (and the Schema That Fixed It)

We run a US directory of special needs schools and ABA therapy providers. Providers pay to be promoted in the places where parents are searching. The …

Data Migration, Conversion, and ETL — What I Actually Did, Across Two Eras

Three words that engineers use interchangeably and shouldn't: Migration is a one-time move — different system, different schema, run once, archive the…

Optimizing an 18 TB Azure SQL Hyperscale Database — Part 2: Smoothing the CPU Load

Previously: we migrated this database from Azure SQL Managed Instance to Azure SQL Hyperscale — not because of its size at the time, but because we co…

Mastering Hive in Flutter: A Step by Step Beginner's Guide to Fast Local Storage

Introduction When building a Flutter application, you'll often need to store data on the user's device. For example: Saving user preferences Storing l…

AWS retired its free database migration assessment tool. The reason should change how you build developer tools.

On May 20, 2026, AWS ended support for DMS Fleet Advisor. Fleet Advisor answered a question every migration team asks first: what is actually in my da…

LioranDB V2 Pre-Alpha Benchmark Summary

Over the past few weeks I've been benchmarking LioranDB V2 , a document database engine written completely from scratch in Rust . Instead of publishin…

Built, not assembled

Most cloud platforms are not platforms. They are holding companies. A database startup gets acquired. A serverless product gets bolted on. An AI infer…

Fast at Lunch. Slow at Scale: Why Your App Gets Slow When Real Data Arrives

A page that feels instant with a few users can become painfully slow when your business grows. The code hasn’t changed. The server hasn’t changed. The…

i have a requirement to create a feedback app, the feedback should be visible only to the person who got the feedback and HR admin, no one else should see the feedback including support person, DBA and others, what is the best way to design it using keys

How to Build Rock-Solid Real-Time Data Pipelines from the Factory Floor IoT

Lessons from hooking up stamping presses, welding cells, and MES without dropping a single byte of data. If you’ve ever been tasked with trying to fee…

Building SaarDB, Part 4: Transactions

In Parts 1-3, we built a storage engine: WAL, memtable, SSTables, and compaction. Every operation is a single GET or PUT. But real applications rarely…

SQLite vs PostgreSQL: Choosing the Right Database

SQLite vs PostgreSQL: Choosing the Right Database tags: database, sql, tutorial, programming tags: database, sql, tutorial, programming Imagine you're…

X-MaP (Cross-Mapped Programming): Treating the Header Row as a Schema, Rows as Instances, and Columns as Lazy Properties

A Japanese-language version of this article is available on Zenn . I've prepared a blank map. Fill in what you need, as your own — and draw the shippi…

What Durable Actually Means for Money-Critical Code

Working on systems that move real money changes what "saved to the database" is allowed to mean. A row existing in Postgres is not the same claim as "…

Defeating the Multi-Tenant SaaS Concurrency Trap in PostgreSQL

Most backend engineers implement multi-tenant quota checks using a standard "read-then-write" pattern. In production, this pattern is highly unsafe: S…

Lucidchart ERD Alternative: A Desktop ERD Tool That Connects to Your Database

Disclosure: I build Schemity , a desktop ERD tool - this post is from our blog and uses it for the examples. TL;DR: Lucidchart draws entity relationsh…

Stop Saying "Just Use Redis": A Key-Value Store Cheat Sheet for System Design Interviews

We’ve all been there. You sketch out a flawless high-level architecture on the whiteboard, and the interviewer leans in: “ Alright, what database are …

I Didn't Plan to Build an Offline-First Attendance System. Firestore Forced Me To.

How accidentally exhausting Firestore's free-tier limit transformed a rushed MVP into a more resilient anti-proxy attendance system. Introduction When…

Inside LioranDB's Full-Text Search Segments

A normal secondary index can answer: status = "active" It cannot efficiently answer: documents containing "distributed database" LioranDB therefore ha…

Cache Invalidation Strategies with Redis

There's an old joke that there are only two hard problems in computer science: cache invalidation and naming things. The joke endures because it's tru…

Refresh-Ahead Caching with Redis

Every cache pattern so far accepts that cache misses happen: a key expires, a request misses, and someone pays the cost of reloading from the database…

Write-Behind (Write-Back) Caching with Redis

Write-through keeps the cache and database consistent by writing to both synchronously, which makes writes as slow as the database. Write-behind takes…

Read-Through and Write-Through Caching with Redis

Cache-aside puts the caching logic in your application. Read-through and write-through move it into the cache layer itself, so the application talks t…

The Cache-Aside Pattern with Redis

Cache-aside is the caching pattern you'll use most, and probably the one you already use without knowing its name. The application checks the cache fi…

Redis Key Expiration, TTL, and Eviction Policies

Redis holds everything in memory, which raises an obvious question: what stops it from filling up and falling over? The answer is two mechanisms worki…

Redis Sorted Sets and Ranked Data

If you learn one Redis structure deeply, make it the sorted set. It's a set where every member carries a numeric score, and members stay ordered by th…

Redis Data Structures: An Overview

The reason Redis solves so many problems is that it isn't one thing, it's a collection of data structures, each with commands tuned for a specific acc…

Database Migrations: Managing Schema Changes as Version-Controlled Code

Database Migrations: Managing Schema Changes as Version-Controlled Code A practical guide to database migrations — the discipline of evolving a databa…