"What If the Data Arrives After the Pipeline Ran?"

What They're Really Testing The interviewer is testing whether you design pipelines for the ideal case or the real case. The ideal case: data arrives in order, dimensions exist before facts, and no corrections are needed. The real case: mobile events arrive days late, upstream dimension changes are delayed, and corrections arrive after reports have been generated. The Two Categories The 60-Second Framework Why Companies Care Cite these in your answer: 'At Uber, 15% of ride events arrive more than 1 hour late due to driver app connectivity. A pipeline that closes hourly partitions loses 15% of rides. At Spotify, podcast listens from offline devices arrive up to 7 days late, causing royalty calculations to be systematically wrong.' Drop one of these in 10 seconds to show late data is not an