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  • Profile photo for Paul Brabban Paul Brabban, Lead Consultant at Equal Experts

    With experience in software development, data engineering and machine learning, I specialise in data-intensive problems and decentralised data engineering at scale. My experience extends to leading teams, technical architecture and product development. Find out more about my experience and publications in my portfolio.

    Contact me to see how I can help at paul@tempered.works.

Rethinking the guest network to improve my home network security

Network diagram showing the internet connected to a router, linked to four devices: tablet, mobile phone, laptop, and IoT device.

I believe that making my guest network my default network reduces the potential harm a compromised app or device can cause. What was my "trusted" network is now my "untrusted" network, with only a few low-risk devices that really need local network connectivity connected to it, isolated from other devices that matter like my phone and work laptop.

It's a simple change in how I use my home network, and does not require in-depth knowledge and experience. Having operated this way at home for a few months now, I've found little impact on day-to-day usability, but it's really helped me sleep better at night. I'll explain what I changed, why, and how I've adjusted my wider thinking on my home network security to take better advantage of this approach.

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Generating portable and user-friendly identifiers

A screenshot of the BigQuery console, with example SQL for generating an identfier from a string value as I outline below

I'll share how I generate unique identifiers from data in 2025, avoiding the pitfalls I've seen along the way. TL;DR: I'm using MD5 to produce a digest from a string or bytes value, then I'm using plain old hexadecimal encoding of that digest, specifying upper or lowercase for the alpha characters. This solution meets the needs I describe next.

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Testing stored procedures

hero image

Whilst I've used and written about UDFs a lot, I can't recall ever having a reason to work with stored procedures. When I was asked how I'd go about wrapping them in automation and testing, I thought it'd be a good excuse to take a look and see how I might go about testing them!

Avoiding CAST ROW in AWS Athena SQL

The Trino issue that makes row aggregations so much easier to work with

There is more than one way to build a ROW in AWS Athena and the underlying Trino engine. It turns out I was doing it the verbose, brittle and really annoying way. Row subqueries are so much better!

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Time travelling with change data capture

Visualisation of effects of end timestamps on a series of transactions

In the last article of the series, I ran into difficulties as I tried to "time-travel" back to earlier points in time. That's an important capability for correct functioning and reproducing results. This article shows how to use window functions (also known as analytic functions) to simplify handling of processing time and avoid the previous problems.

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Map over an array in BigQuery

SQL snippet for map explained in post

This walkthrough shows how I can use the functional programming techniques map and filter that I already know and love in SQL engines like BigQuery. These techniques give me a lot of processing power whilst keeping my SQL simple and relatively easy to understand. Unlike custom code, I can use the same SQL and infratructure I'd use to process ten rows to process ten billion rows in seconds.