RDS Postgres upgrade

When upgrading your RDS PostgreSQL databases to version 16.6, it's important to consider the recommended upgrade path and potential implications. While the AWS RDS console may show version 16.6 as an available option in the drop-down box for your database on version 13.12, it's generally recommended to follow a step-by-step approach for major version upgrades.

The recommended way to upgrade is to perform upgrades one major version at a time. This means you should first upgrade from version 13.12 to version 14, then to version 15, and finally to version 16.6. This approach allows you to test and ensure compatibility at each step, reducing the risk of unexpected issues.

However, in some cases, it is possible to skip versions and upgrade directly to a higher major version. If you choose to do this, be aware that there may be limitations and additional considerations, especially for upgrades to version 11 and beyond.

Before proceeding with any upgrade, it's crucial to:

1. Thoroughly test the upgrade process in a non-production environment.
2. Ensure your applications are compatible with the target version.
3. Back up your databases.
4. Plan for potential downtime, especially for major version upgrades.

For Multi-AZ deployments, keep in mind that when you upgrade the primary instance, any associated read replicas will also be upgraded to the same version.

It's also important to note that most PostgreSQL extensions are not automatically upgraded during the engine upgrade process. You'll need to upgrade these extensions separately after the engine upgrade is complete.

Regardless of the upgrade path you choose, make sure to set your backup retention period to a value greater than 0. This allows Amazon RDS to take snapshots during the upgrade process, providing an additional safety measure.

Given the complexity of major version upgrades, it's advisable to review the official AWS documentation for detailed steps and best practices before proceeding with your upgrade plan.
Sources
Choosing a major version for an RDS for PostgreSQL upgrade - Amazon Relational Database Service
Upgrades of the RDS for PostgreSQL DB engine - Amazon Relational Database Service
Upgrading PostgreSQL extensions in RDS for PostgreSQL databases - Amazon Relational Database Service
Amazon RDS for PostgreSQL now supports major version 16