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Ruud Juffermans

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Articles on data and AI

On what it really takes to build a data foundation that holds — written from the projects on this site.

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Project15 articles

The offset ledger: never commit past an open window

September 13, 2026 · 11 min read

The bug that made 169,000 good events "late"

September 13, 2026 · 10 min read

Turning a full snapshot feed into a change stream (and why you still need a heartbeat)

September 13, 2026 · 9 min read

No source, no answer: enforcing citations in code, not in the prompt

September 13, 2026 · 11 min read

Cosine similarity is not a relevance score

September 13, 2026 · 9 min read

A human-in-the-loop agent with LangGraph interrupt()

September 13, 2026 · 10 min read

One licence-plate range, three datasets: reproducible sampling for a warehouse

September 13, 2026 · 10 min read

SCD type 2 in dbt with window functions only

September 13, 2026 · 10 min read

A digital twin that only says what it can prove

September 11, 2026 · 4 min read

Every department reports a different revenue figure: why, and what to do

August 18, 2026 · 4 min read

Real-time transit delays on Kafka: a streaming pipeline that runs 24 hours unattended

August 10, 2026 · 4 min read

RAG over Dutch court rulings: every answer with a source, or no answer

August 8, 2026 · 4 min read

CI for a dbt project: every pull request builds the whole warehouse

August 3, 2026 · 4 min read

Dutch public holidays in SQL: a date dimension that's right even on 5 May 2016

August 3, 2026 · 10 min read

An open-data warehouse done properly: dbt, tests and a Kimball star schema

July 26, 2026 · 4 min read