Which combination of migration patterns will reduce licensing costs and operational overhead?

Explanations:

Lift and shift migrations typically do not optimize licensing costs, especially for Oracle, which can be expensive on EC2 due to licensing fees. This option does not leverage any cost-saving benefits or managed services, leading to higher operational overhead.

Migrating the Oracle data warehouse to Amazon Redshift allows the company to use a more cost-effective, managed data warehouse solution. Redshift has a different pricing model and can reduce licensing costs compared to maintaining Oracle on EC2. This migration pattern also reduces operational overhead by using a fully managed service.

Similar to option A, lifting and shifting PostgreSQL databases to EC2 does not optimize for licensing or operational overhead. While PostgreSQL itself is open-source, managing it on EC2 incurs overhead and does not take advantage of the benefits offered by managed services like RDS.

Migrating PostgreSQL databases to Amazon RDS for PostgreSQL reduces operational overhead by utilizing a managed service that automates tasks such as backups, patching, and scaling. This approach allows the company to focus on application development rather than database management, which can also lead to cost savings.

While migrating the Oracle data warehouse to an Amazon EMR managed cluster could reduce some operational overhead associated with data processing, it does not directly address licensing costs associated with Oracle. EMR is more suitable for big data workloads rather than traditional data warehousing use cases.