Start with the application boundary
Our recommendation is to shortlist RDS first for an application already running on AWS, and OCI Database with PostgreSQL first for one running on Oracle Cloud. Putting the database on another provider adds a network boundary to every database interaction. Measure latency, review transfer costs, and decide who will diagnose failures across that boundary before moving for a lower headline rate.
For a new application, draw the whole setup: web processes, background workers, database, uploads, and recovery copies. Choose a provider around the complete application and its operating requirements. The table describes documented billing and recovery rules; it is not a performance benchmark or a monthly quote.
Match the failure you need to survive
RDS has different Single-AZ and Multi-AZ deployment models. OCI separates node placement from data placement. Use the topology row to identify the configuration you are actually comparing; the number of database nodes alone does not establish equivalent protection.
Write an acceptance scenario such as: “The app must resume writes after losing one availability zone, and the team must know how to reconnect.” Check each proposed topology against that scenario. Test connection retries and the application’s behavior during a failover, including background jobs. A provider’s failover feature does not validate your application recovery path.
Resolve the OCI placement tradeoff early
The shared recovery rows expose an important planning constraint: regional data placement and cross-region backup copying are separate choices on OCI. Do not assume a topology selected for local availability also permits the backup-copy route you intend to use.
Our recommendation is to write down the required failure domain, the backup destination, and the restore procedure before provisioning. If cross-region recovery is mandatory, verify an eligible backup-copy configuration or separately assess Oracle’s warm standby replication. Replication needs its own cost and recovery review; it is not a substitute for a retained backup after accidental deletion.
On RDS, distinguish a new database created by point-in-time recovery from the existing application’s live endpoint. The team’s runbook must include validation, connection changes, and any parameter or access configuration.
Compare complete recurring cost
Ask for two estimates with the same required location, runtime, recovery policy, and availability objective. Record these inputs alongside the quotes:
- Compute class or shape, memory, processor architecture, and every database node.
- Storage growth and the performance option needed for the measured workload.
- Backup retention, retained snapshots or copies, and cross-region transfer.
- App-to-database networking, monitoring, and applicable database service or support fees.
- Engineering time for migration, recovery drills, and ongoing operations.
Do not treat a vCPU and an OCPU as a universal performance conversion. Benchmark the queries and concurrency that matter to the app. Apply credits and commitments only after comparing the recurring baseline.
A decision you can defend
Prefer RDS when staying within the app’s AWS environment meets the requirements with less operating work. Prefer OCI when the application belongs on OCI and the selected node, storage, and recovery configuration meets the same requirements. Move across providers only when the measured benefit justifies migration and ongoing ownership.
Before committing, rehearse an export and import, check required extensions and versions, and define the cutover and rollback window. For the whole application rather than only its database, use the PostgreSQL web-app hosting guide.