GMT windows and job markers
Pipeline KPIs can move when clocks and job tags move—not when the warehouse does.
Teams serving UK consumers often mix UTC warehouse timestamps with GMT operations calendars. A cohort day that spans the wrong midnight shifts every freshness and completeness cell without anyone shipping a pipeline change.
Missing or duplicated job markers create similar ghosts: returning partitions appear as new loads, and day-seven rates look healthier or worse depending on merge rules.
Agree on a single reporting clock, stamp every job with a stable marker, and document how late arrivals join the window. Incident Window Rebuild studies often start here.