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, …
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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…
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…
Why Even Advanced AI Breaks Stock Registers: 12 Years of Snapshot Log Evolution and RDBMS Physics
stock balances is a minefield**. In SQL textbooks, everything looks clean: run SUM(quantity) over transaction history or use a ROW_NUMBER() window fun…
SQL Design & Query Reference
I have professionally worked with four different SQL database types PostgreSQL , MySQL & MariaDB (InnoDB), MSSQL SQL Server 2008+ and Oracle 19c +…
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…
REST-style GraphQL — one line of Java handles filtering + sorting + pagination + stats + CSV export.
(Demo's in Chinese but you'll get the idea in 30 seconds) 👇 https://demo-bs.zhxu.cn/ A backend engineer's confession: you just wrote 100 lines of Java…
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…
Azure SQL Managed Instance vs Azure SQL Database: How I Actually Made the Call
A field decision from a real production migration — not a feature-matrix blog. When we migrated two internal enterprise applications (plus an integrat…
Where Should the Foreign Key Go?
This is Part II of a series about vertical partitioning for large text columns. Part I explains why we separated the large text from the main table. I…
You Cannot Judge Coupling and Cohesion From the Same View
Disclosure: I build Schemity , a desktop ERD tool - this post is from our blog and uses it for the examples. TL;DR: Coupling and cohesion are question…
Database Context Views Should Show the Relationships They Hide
Disclosure: I build Schemity , a desktop ERD tool - this post is from our blog and uses it for the examples. TL;DR: Focused sub-diagrams remove noise,…
I Reduced a 12-Second SQL Query to 300ms Without Changing the Server
Performance optimization isn't always about buying better hardware. Sometimes, it's about asking the database the right question. Introduction A slow …
SQLite Internals: lcd-ex vs hctree; PostgreSQL 19 SQL/PGQ Rewrites & pg_timetable Migration
SQLite Internals: lcd-ex vs hctree; PostgreSQL 19 SQL/PGQ Rewrites & pg_timetable Migration Today's Highlights This week's highlights feature a de…
DuckDB Iceberg MERGE, PostgreSQL GUCs, SQLite Optimization Checklist
DuckDB Iceberg MERGE, PostgreSQL GUCs, SQLite Optimization Checklist Today's Highlights This week's highlights include powerful new Iceberg data manip…
Epic Clarity Data Model Guide for Healthcare Data Engineers
Epic is installed at approximately 38% of US hospitals . If you work in healthcare data engineering long enough, you will encounter Epic Clarity. This…
Digital Q.DataBase 18.2: новая архитектура, расширение совместимости и новые инструменты миграции
Переход крупных корпоративных систем на отечественные СУБД остается одной из наиболее актуальных задач последних лет. Однако основная сложность подобн…
How do I answer "what did my data look like last month" in Postgres?
Sooner or later, someone asks: "What did this customer's plan look like when they signed up last February?" The current row won't tell you that; it's …
AI-Assisted SQL Development with Claude Code — Rules, Skills and Agents That Enforce Conventions
A stored procedure, a migration script, a complex report — Claude Code writes them in seconds. That's the easy part. The hard part starts afterwards: …
Open Source Project of the Day (#116): SAG — Multi-Hop RAG Retrieval via SQL JOINs Instead of PageRank
Introduction "Graph RAG typically pre-builds a global graph offline, then uses PageRank for query-time scoring and expansion — but PageRank has decay:…
The Database Architect Teaches His Nephew: Where the Real Interview Happens
Same uncle, this time in "Database Architect" mode. Same nephew, this time asking the question every backend developer eventually asks out loud. Part …
Data Engineer LeetCode: What to Grind and What to Skip
I spent about 80 hours grinding LeetCode before my first FAANG data engineering loop. Binary trees, dynamic programming, graph traversal. I could reve…
How to implement RBAC in Go
My intention with this article is to show how I'd implement role-based access control (RBAC) if I had to - in the hope that it acts as a guide for whe…
When to denormalize, when to join: A ClickHouse guide (2026)
Denormalization has been the standard approach to analytical data modeling for good reason. Moving joins, lookups, and business rules out of query tim…
sqlex — A Modern Drop-in Replacement for jmoiron/sqlx
title: sqlex — A Modern Drop-in Replacement for jmoiron/sqlx published: false description: sqlex is a fully API-compatible modernization of jmoiron/sq…
Star Schema vs Snowflake Schema: Which to Use and When
The difference between a star schema and a snowflake schema is smaller than the debate around it suggests. Both are dimensional models — a central fac…
The Fastest Way to Add Reporting to Your Internal Tool
You built a solid internal tool. It manages customers, tracks orders, handles operations. Your team lives in it every day. Then someone in leadership …
Designing SaaS Database Architecture: Users, Organizations, Subscriptions, and Billing
SaaS database architecture decisions made in the first week will haunt you for years. This guide walks through a battle-tested multi-tenant schema des…
DuckDB 1.5.2, PostgreSQL Internal Stats, and SQLite Virtual Table xUpdate Deep Dive
DuckDB 1.5.2, PostgreSQL Internal Stats, and SQLite Virtual Table xUpdate Deep Dive Today's Highlights This week brings a stable new patch release for…
Modelling, Joins, Relationships and different Schemas
Data Modelling is the invisible architecture that structures your data so it is fast accurate and scalable. It is the process of identifying, organizi…