Product teams often rehearse Black Friday volume. Fewer teams rehearse Songkran, Constitution Day, or a Monday bridge holiday when a supplier’s SFTP folder simply stays empty.
The pattern we see
Schedulers fire on their usual cron. Extractors treat “no file” as “zero rows succeeded.” Downstream transforms publish a quiet night as a legitimate zero, and morning dashboards look oddly calm until a store manager asks where yesterday’s tickets went.
The root is rarely exotic. It is a missing join between the corporate holiday calendar and the expectation that upstream systems publish every night.
Practical checks
- Maintain an explicit holiday table for Thailand (and any other markets you load).
- Distinguish “zero because closed” from “zero because failed” with a status flag the warehouse can query.
- Give operators a one-page Eve replay card: which feeds to wait for, which to skip, which to backfill after the holiday.
If your December and April nights are the ones that wake people up, an ETL Reliability Assessment often starts with the calendar before touching transformation logic.