AWS Database Migration Service (AWS DMS)

Correct Answer: Use AWS Database Migration Service (DMS) to perform a full load migration of the Oracle database to Amazon RDS for PostgreSQL during off-peak hours, followed by a CDC (change data capture) replication to keep the target database in sync until the final cutover.

The best approach for the company to migrate their on-premises Oracle database to Amazon RDS for PostgreSQL with minimal downtime is to use AWS Database Migration Service (DMS). By performing a full load migration during off-peak hours, followed by a change data capture (CDC) replication, they can keep the target database in sync until the final cutover. This allows them to minimize downtime and ensures that the database remains operational during business hours. The other options have limitations that make them less suitable. Converting the schema using AWS Schema Conversion Tool (SCT) and then performing a one-time full load migration during maintenance window may result in longer downtime. Creating a read replica using DMS and then converting the schema is not an ideal approach for a direct Oracle to PostgreSQL migration. Taking a backup, restoring it to an EC2 instance, converting the schema, and then migrating the data introduces unnecessary complexity and potential compatibility issues. Therefore, using AWS DMS with a full load and CDC replication is the most appropriate solution to meet the company's requirements of minimizing downtime and ensuring a smooth migration within the tight deadline.

Correct Answer: The source database remains fully operational, allowing minimal downtime during the migration

When using AWS Database Migration Service (AWS DMS), the source database remains fully operational during the migration process. This allows for minimal downtime and ensures that applications can continue to access and use the source database while the data is being migrated to the target database. The other options are incorrect because: 1. The source database is not taken offline or made inaccessible during the migration. 2. AWS DMS is designed to minimize impact on the source database's performance and does not significantly increase latency. 3. The source database is not automatically replaced by the target database; they continue to exist independently until the migration is complete and the target is ready to serve as the primary database.

Correct Answer: Supporting migrations from on-premises databases to Amazon RDS

AWS Database Migration Service (AWS DMS) is a service that enables the migration of databases from on-premises environments to Amazon RDS or other AWS database services. It supports various source and target database engines, allowing for heterogeneous migrations. AWS DMS handles the data replication process, ensuring minimal downtime during the migration. However, it does not automatically scale the source database based on the migration workload, optimize queries and indexes during migration, or provide a fully managed service for deploying and managing databases on AWS. Those capabilities are beyond the scope of AWS DMS, which primarily focuses on the migration process itself.