Set up cascading read replicas for a Cloud SQL destination instance

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Overview

Database Migration Service lets you migrate data to a Cloud SQL destination instance,and then set up cascading read replicas for that instance.

Cascading read replicaslet you create a read replica under a Cloud SQL read replica in the same ordifferent region before promoting your instance to primary. You can add up to fourlevels of cascading read replicas, including the primary instance.

Set up cascading read replicas

To migrate your data to a Cloud SQL destination that is using cascading readreplicas:

  1. Set up and start your migration job. For more information, seeCreate a migration job.

  2. Wait until the full dump phase of the job completes and the migration jobenters the change data capture (CDC) phase. Your migration job is in the CDCphase when theStatus column in theMigration jobs page indicates aCDCsubstatus.

  3. Once in the CDC phase, you can set up your cascading read replica. Forinformation about how to create cascading read replicas for a Cloud SQL destination instance, seeSet up a cascading replica.

  4. You can promote your Cloud SQL replica to primary instance using Database Migration Service.For information about promoting a destination instance, seePromote a migration.

When you promote the Cloud SQL replica to a primary instance, the replica's cascadingreplica hierarchy is retained.

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Last updated 2025-12-17 UTC.