UTC, Time Zones, and ETL: A Real Story About a Silent DST Bug (and a Lucky Escape)
The guiding principle (the motto) Keep UTC for as long as possible. Change to a local timezone only when it is truly required. This principle was not theoretical. It emerged from a real incident — one that almost became a production bug, and only didn’t because of a fortunate configuration coincidence. Why time zones are dangerous in ETL Time-related issues are among the hardest problems in data engineering because: ...