Answer: Create an Aurora read replica of the RDS for PostgreSQL DB instance. Promote the Aurora read replica to a new Aurora PostgreSQL DB cluster.

## Explanation **Correct Answer: B** Creating an Aurora read replica of the RDS for PostgreSQL DB instance and then promoting it to a standalone Aurora PostgreSQL DB cluster is the best approach for minimal downtime and least operational overhead. ### Why Option B is Correct: 1. **Minimal Downtime**: The Aurora read replica continuously replicates data from the source RDS PostgreSQL instance. Once the replica is caught up, you can promote it with minimal downtime (typically just the time needed to promote the replica and redirect applications). 2. **Least Operational Overhead**: AWS manages the replication process automatically. You simply create the read replica through the AWS Management Console, CLI, or API, and AWS handles the data synchronization. 3. **Seamless Migration**: After promotion, the Aurora read replica becomes a standalone Aurora PostgreSQL DB cluster that can serve as the new primary database. 4. **AWS Best Practice**: This is AWS's recommended method for migrating from RDS PostgreSQL to Aurora PostgreSQL. ### Why Other Options Are Not Optimal: **Option A**: Creating a DB snapshot requires downtime during the snapshot creation and restoration process. The database would be unavailable during the snapshot, and the migration would involve more manual steps. **Option C**: Data import from S3 requires exporting data to S3 first, which adds complexity and additional steps. It also requires more manual intervention and likely more downtime. **Option D**: Using pg_dump requires manual backup and restore operations, which involves significant downtime during the backup and restore process, and more operational overhead for managing the utility and ensuring data consistency. ### Key Benefits of Aurora Read Replica Migration: - **Continuous Replication**: Data is replicated in near real-time - **Minimal Application Downtime**: Only brief downtime during promotion - **Automated Process**: AWS manages the replication infrastructure - **Rollback Capability**: You can keep the source RDS instance running until you verify the Aurora cluster is working correctly - **Compatibility**: Aurora PostgreSQL is designed to be compatible with RDS PostgreSQL, making this migration path reliable.

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