Process only new records

Your weather pipeline writes data to a table, but if you run it twice, you'll get duplicates. Production workflows need to be duplicate-safe (idempotent) — running them multiple times should produce the same result as running once. You'll add a comparison step that checks incoming data against what's already stored.

You'll extend the workflow by adding a Data Table Get row(s) node to read existing records and a Code node that filters out duplicates by comparing city and date, so only genuinely new records get written.