Data Quality

Healing Tables: When Day-by-Day Backfills Become a Slow-Motion Disaster

It was 2 AM on a Saturday when I realised we’d been loading data wrong for six months. The situation: a customer dimension with three years of history needed to be backfilled after a source system migration. The previous team’s approach was straightforward—run the daily incremental process 1,095 times, once for each day of history. They estimated three weeks to complete. What they hadn’t accounted for was how errors compound. By the time I looked at the data, we had 47,000 records with overlapping date ranges, 12,000 timeline gaps where customers seemed to vanish and reappear, and an unknowable number of missed changes from when source systems updated the same record multiple times in a single day.

Saturday, February 7, 2026 Read

Context Engineering: The New Must-Have Skill for Data Engineers

Last year I watched a colleague ask AI to help write a dbt model. The AI spit out perfectly functional SQL—clean syntax, proper CTEs, the works. Looked great. Then I noticed the table would eventually hold 800 million rows. No partitioning. No clustering. Just a raw, unoptimised heap waiting to turn into a query performance nightmare (that would likely become my nightmare to fix). The engineer wasn’t at fault. The AI wasn’t at fault either, really. The AI simply didn’t know that our environment clusters large tables by date. It didn’t know our team’s conventions around incremental models. It couldn’t know, because nobody had told it.

Saturday, January 31, 2026 Read

That Tuesday Morning When I Finally Fixed Our Ten-Minute Queries

The Ten-Minute Query I’m sitting at my laptop on a Tuesday morning, waiting. The progress bar on my screen says ‘Query running… 4 minutes, 37 seconds.’ I lean back in my chair and let out this long sigh that probably says more than I intended. My manager walks past my desk. She glances at my screen, and I can see that look—the one that says she already knows what I’m about to tell her. I didn’t need to explain.

Friday, January 16, 2026 Read

The Guerrilla Guide to Data Engineering Interviews

The Scenario That Changes Everything Picture this: You’re sitting in an interview room—or more likely these days, staring at a Zoom window with your carefully curated bookshelf background—and the interviewer asks you about data quality. “Tell me about your experience with data quality,” they say. You have two choices. Choice A: “Data quality is really important in data engineering. It involves ensuring data is accurate, complete, consistent, and timely. I believe strongly in implementing data quality checks throughout the pipeline.”

Sunday, January 11, 2026 Read

The Four Stages of Data Quality: From Hidden Costs to Measurable Value

This is the fundamental problem with data quality. You know it matters. Everyone knows it matters. But until you can quantify the impact, connect it to business outcomes, and build a credible business case, it remains this abstract thing that’s important but never urgent enough to properly fund. I wrote a practical guide to data quality last week that walks through hands-on implementation—the SQL queries, the profiling techniques, the actual mechanics of finding and fixing data issues. Think of that as the “how to use the tools” guide. This article is different. This is the “why these tools matter and how to convince your organisation to actually use them” guide.

Monday, November 24, 2025 Read

When Your Data Quality Fails at 9 PM on a Friday

When everything goes wrong at once It’s 9 PM on a Friday. You’re halfway through your second beer, finally relaxing after a brutal week. Your phone buzzes. Then it buzzes again. And again. The support team’s in full panic mode, your manager’s calling, and somewhere in Melbourne, two very angry guests are standing outside the same Airbnb property—both holding confirmation emails that say the place is theirs for the weekend.

Saturday, November 22, 2025 Read

Why Dimensional Modelling Isn't Dead—It's Just Getting Started

The Great Data Modelling Debate Nobody Asked For Another meeting where someone confidently declared, “We don’t need data modelling anymore—just dump everything in the data lake and let analysts figure it out.” I’ve heard variations of this statement for years now, in meetings or at conferences. The pitch is always the same: traditional data warehousing is dead, dimensional modelling is a relic from the 90s, and modern big data tools have made structured modelling obsolete. Schema-on-read is the future. Agility over architecture.

Friday, November 7, 2025 Read

Continuous Integration for Data Teams: Beyond the Buzzwords

The Day Everything Broke (And How CI Could Have Saved Us) Picture this: It’s 9 AM on a Monday, and your Slack is exploding. The executive dashboard is showing impossible numbers. Customer support is fielding complaints about incorrect billing amounts. The marketing team is questioning why their conversion metrics suddenly dropped to zero. You trace it back to a seemingly innocent change you merged Friday afternoon—a simple column rename that seemed harmless enough. But that “harmless” change cascaded through your entire data pipeline, breaking downstream models, dashboards, and automated reports.

Saturday, June 28, 2025 Read

Streamlining Data Pipeline Reliability: The Write-Audit-Publish Pattern

Introduction: Why Safe Data Pipelines Matter In the world of data engineering, there’s a constant challenge we all face: how do we ensure our production data remains reliable and error-free when deploying updates? Anyone who’s experienced the cold sweat of a bad deployment affecting critical business data knows this pain all too well. Enter the Write-Audit-Publish pattern—a robust approach that can significantly reduce the risk of data pipeline failures. This pattern, which shares DNA with the well-known Blue-Green deployment strategy from software engineering, creates a safety net that can save your team countless hours of troubleshooting and emergency fixes.

Sunday, May 18, 2025 Read

Leveraging LLMs for Business Impact: Part 2 - Building an AI Data Engineer Agent

Introduction In Part 1 of this series, we explored the theoretical foundations of Large Language Models (LLMs), Retrieval Augmented Generation (RAG), and vector databases. Now, it’s time to put theory into practice. This is going to be a long read, so grab some coffee, and one (couple) of your favourite biscuits. One use case for leveraging LLM’s, is creating of a Agent - a Senior Data Engineer AI that automatically reviews Pull Requests in your data engineering projects. This agent will be that nit picky Data Engineer that enforces SQL formatting standards, ensure naming and data type consistency, validate data quality checks, and suggest improvements based on best practices. By integrating this into your GitHub workflow, you can maintain higher code quality, accelerate onboarding for new team members, and reduce the burden of manual code reviews.

Saturday, March 8, 2025 Read

Maximising Data Impact: A Guide to Effective Data Engineering

Introduction Creating impact goes far beyond writing efficient code or building robust pipelines. It’s about understanding how your work translates into tangible value for stakeholders across the organisation. Types of Impact Our work forms the backbone of data-driven decision making in organisations. However, measuring and communicating this impact isn’t always straightforward. If you feel your work isn’t making a meaningful difference, it might be time to pivot your focus or approach. Understanding the various ways we create value helps guide these decisions and ensures we’re contributing in ways that matter.

Saturday, February 15, 2025 Read

Mastering Data Engineering: Insights and Best Practices

Introduction I have been working with Data for a bit over 17 years now, I have seen it evolve from its nascent stages to a cornerstone of the tech industry. The journey has been nothing short of revolutionary, impacting businesses and society at large. The evolution and the role of a data engineer have expanded, requiring not just technical skills, but a deep understanding of business, security, and the human element within technology.

Saturday, March 30, 2024 Read