Challenge · intermediate · 25 min · Premium
Two clocks
Halvard's nightly cut assigns the last hour of deliveries to the wrong day, but only some nights. One system stamps UTC, one Oslo local time, and the boundary moves twice a year. Find the seam, prove it with the data, and fix the cut.
Brief
- Customer
- Halvard Freight (synthetic customer; every timestamp and record on this box is made up for the exercise)
- Situation
- Finance says the daily delivery counts are off by a few dozen on some nights and exact on others. The receiver writes delivery times as it receives them; the nightly cut groups them by day. Nobody has touched either in months. The pattern started at the end of March.
- Your role
- You are the FDE on the Halvard engagement. You have the recorded deliveries, the cut job's config and code, and a dry-run of the cut.
- Goal
- Find the two clocks, name the boundary that moves, prove which deliveries land on the wrong day, and make the cut run in one clock.
Objectives
- 1.Name the field that carries no offset (you commit to an answer)
- 2.Name what moved at the end of March (you commit to an answer)
- 3.Count the deliveries in the two files whose local day and UTC day differ (you commit to an answer)
- 4.Make the cut run in one clock and show the dry run stable across the change
Mission workspace
This mission is part of premium, with every challenge and incident in the lab. The brief above is the whole problem; the box, the hints and the debrief are what you unlock.
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