ShagilityAgile Data Coach, Author, Agile Data Guides · Your Agile Data Guide

The Hidden Complexity Behind ‘Sexy’ Demos #substack #shorts

15 Aug 2026 · 1 min

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Shagility breaks down the engineering behind impressive product demos that answer simple questions. Building a single-customer view requires matching records across three systems, aggregating transactions, and reconciling reference tables that change over time. What looks effortless on stage is actually complex data integration, temporal modeling, and versioned ETL code.

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those sexy demos where, you know, they ask a natural language question of how many customers I've got and it works. And then you sit there and you go, so hold on, let's just put all these Lego blocks we just talked about together. So I have customer in 3 systems and I need to bring it in and give me a single list of customer by doing some matching to say those customer records are the same. And then I'm going to get transactions from all those other systems and then combine it. So I have a single view of everything that we did with that customer. Some of that data might be driven by reference tables, right? So we have this set of manually maintained tables outside those systems that are saying, this is this, or this is these dates, or there's a series of flags, and they change over time. So we know that, you know, a month ago this was the rule, and this month this is the rule. We change our ETL code over time. So we have these version sets of ETL. Our data changes over time. So the data we are collecting in from all those source systems is temporal, and it has effective dates and change records. Our business logic that we use in our ETL may change.