Ivan Luminaria/
Tags/
Data-Warehouse/

Data-Warehouse

4 million euros, two multinationals, zero software: the true story of a failure foretold

An insurance client spent over 4 million euros hiring two IT consulting giants to build a custom management system. The result: nothing. By contrast, a data warehouse built by two people in 3 years with 60,000 lines of code that runs every single day.

30 December 2025·7 mins

SCD Type 2: the history the business didn't know it needed

A sales director asks how many customers were in the North region last June. The DWH can't answer because every update overwrites previous data. How I implemented an SCD Type 2 with surrogate keys and validity dates to give the business back its historical memory.

11 November 2025·13 mins

Wrong grain: when the fact table can't answer the right questions

A fact table built on monthly invoice totals looked perfect. Then the business asked for product-level, line-level, customer-level detail. And the data warehouse went silent.

21 October 2025·7 mins