Late-Arriving Facts: Inserting Into Closed Partitions

Concepts covered: dmLateArriving

After you identify the late-arriving fact scenario, the interviewer will ask: 'Show me how your pipeline handles it.' This is where candidates who have only read about late data stall, and candidates who have operated it in production accelerate. The answer involves partition management, aggregate recomputation, and a cascade strategy. Three Strategies: Know All Three, Recommend One The Cascade Problem Interviewers Probe Narrate the cascade: 'I insert the late fact into the March 15 partition. But the daily revenue aggregate for March 15 was already computed as $10M. It is now stale. The monthly aggregate is stale. The dashboard tile is stale. I must mark affected aggregate partitions for recomputation, recompute them, and invalidate dashboard caches. Without this cascade, the base data is

About This Interactive Section

This section is part of the Late-Arriving Data: Advanced lesson on DataDriven, a free data engineering interview prep platform. Each section includes explanations, worked examples, and hands-on code challenges that execute in real time. SQL queries run against a live PostgreSQL database. Python runs in a sandboxed Docker container. Data modeling problems validate against interactive schema canvases. All content is framed around what data engineering interviewers actually test at companies like Meta, Google, Amazon, Netflix, Stripe, and Databricks.

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