# A real-shaped payments ETL matches the section's worked example

Canonical URL: <https://datadriven.io/problems/a-real-shaped-payments-etl-matches-the-sections-worked-exam-ee198f0f>

Domain: Pipeline Design · Difficulty: medium

## Problem

A real-shaped payments ETL matches the section's worked example. It pulls Stripe payments using NOW() minus a day, joins customer state from Postgres, and row-by-row INSERTs into plain Snowflake. Three idempotency bugs hide in 24 lines (wall-clock window, append-only writes, no partition column). Apply the section's refactor checklist so the pipeline passes both the two-run test and the backfill test.

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