# A Debezium CDC pipeline streams the payments database to a downstream Iceberg lakehouse and a regula Canonical URL: Domain: Pipeline Design ยท Difficulty: medium ## Problem A Debezium CDC pipeline streams the payments database to a downstream Iceberg lakehouse and a regulatory reporting system. A DBA runs ALTER TABLE on payments.transactions in production: add merchant_country (additive), drop legacy_clearing_code (destructive). Both schema-change events are already in the change stream. The section names three enforcement policies: allow-additive (additive changes flow through, destructive changes blocked), block-breaking (any non-additive change halts the stream and pages on-call), and quarantine (destructive changes route to a quarantine topic for human decision). Set the CDC schema policy by adding a policy enforcement transform between Debezium and the downstream consumers whose name states which of the three policies it applies, and add a quarantine destination for blocked changes. ## Related - [All practice problems](https://datadriven.io/problems) - [Mock interview mode](https://datadriven.io/interview/a-debezium-cdc-pipeline-streams-the-payments-database-to-a-d-22340ae2) - [System Design Interview Questions](https://datadriven.io/data-engineering-system-design) - [Data Engineering Interview Prep Guide](https://datadriven.io/data-engineer-interview-prep) - [Daily Challenge](https://datadriven.io/daily) --- Source: DataDriven (https://datadriven.io). 100% free data engineering interview prep. Live code execution against Postgres 16, Python 3.11, and Spark sandboxes. No paywall, no premium tier, no signup gate.