Track · 2:29 · Liner note
Same Result, Every Time
An idempotent operation leaves the same final state no matter how many times it runs, which makes retries and reruns safe.
Run it once or run it five times, and the table ends up the same. That is idempotency, and Same Result, Every Time is its promise. It is what lets a scheduler retry a failed job, an engineer rerun yesterday and a consumer receive the same message twice without the numbers drifting.
Build it in with overwrite-by-partition, keyed upserts and deduplication on a stable ID instead of blind appends. Then test it the dull way: run the job twice and compare the counts. If they differ, you have found a future incident.