Track · 2:30 · Liner note
Backfilling Yesterday
A backfill re-runs a pipeline for past dates to fill a gap or correct history, and it is safe only when each run replaces its own period instead of adding to it.
Yesterday’s load failed at three in the morning and nobody noticed until the dashboard showed a hole. Backfilling Yesterday is the careful repair: run the pipeline again for the missing date and nothing else. The test of a good backfill is that running it twice changes nothing, because each run replaces its own slice instead of appending to it.
Keep the range explicit, run it in chunks and check row counts against the source before announcing the fix. Tell downstream consumers that history changed. A silent correction is a second incident.