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How does DMS support continuous data replication using change data capture to minimize downtime during a migration?

Intermediate

Answer

DMS change data capture, or CDC, continuously monitors the source database's transaction logs for new changes after the initial full data load has completed, applying those same changes to the target database in near real time, meaning the target database stays continuously synchronized with the source right up until the moment you are ready to perform a final cutover, dramatically reducing the actual downtime window compared to a traditional one time data dump migration approach.

aws dms modify-replication-task --replication-task-arn arn:aws:dms:us-east-1:123456789012:task:my-task --migration-type cdc

Real-world example A company migrating a critical customer database keeps the target database continuously synchronized using DMS CDC for two weeks while thoroughly testing the new environment, then performs a final cutover during a brief maintenance window with only a few minutes of actual downtime.

Common follow-ups: How does DMS handle conflicts if data changes on both source and target simultaneously?;What happens if CDC replication falls behind the source database's rate of change?

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