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Batch & Streaming · Streaming Processing

What is CDC?

Easystream-28
CDCDebeziumKafkaOLTP

Question

What is Change Data Capture (CDC)?

Solution

CDC streams row-level changes from a database (inserts, updates, deletes) as events, instead of only taking nightly full dumps.

Tools like Debezium read the DB transaction log (WAL / binlog / redo) and publish to Kafka.

OLTP Postgres
   |  (WAL)
   v
 Debezium --> Kafka topic orders.CDC
                 |
                 +--> Flink / Spark SS --> lakehouse
                 +--> search indexer

Why DEs love it

  • Near-real-time warehouse sync
  • Lower load than repeated SELECT * dumps
  • Captures deletes and updates clearly

Watch-outs

  • Schema changes
  • Snapshot bootstrap for initial load
  • Ordering and idempotent apply into the sink

Interview tip: "CDC = turn database commits into a stream." Contrast with full-table batch extract.

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