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Idempotent upsert (safe to re-run)

senior · python🔒Walkthroughs

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Idempotent upsert (safe to re-run)

Apply a batch of updates to a keyed table so the operation is idempotent — running it twice with the same input gives the same result as running it once (no duplicates, no drift). This is what makes a pipeline safe to retry.

table is a dict mapping id -> record. updates is a list of record dicts, each with an "id" key. Upsert each update (insert if new, overwrite if the id exists) and return the new table. Do not mutate the input table.

Python 3.12, standard library only — no pip installs.

solution.py

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