idempotent-script-design
Use this skill when writing scripts, cron jobs, data pipelines, or any automated process that may be run multiple times. Design every operation to be safely re-runnable without side effects.
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Idempotent Script Design
An idempotent operation produces the same result whether run once or ten times.
Techniques:
- Check before create:
CREATE TABLE IF NOT EXISTS,mkdir -p, check file existence before writing. - Upsert instead of insert: Use
INSERT ... ON CONFLICT DO UPDATEin SQL. - Atomic writes: Write to a temp file, then rename — prevents corrupt partial output.
- Track progress: Write a completion marker or checkpoint so reruns skip done work.
Testing idempotency: Run your script twice on the same input and verify the output is identical.
Anti-patterns:
- Appending to a file without checking if the data is already there.
- Inserting rows without checking for duplicates.
- Repository
- aiming-lab/MetaClaw
- Commit
922caf3
- Last updated
- First committed
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