Posted On: Oct 15, 2020
Starting today, Amazon RDS for PostgreSQL will concurrently upgrade all of your in-region read replicas along with the upgrade of your primary database instance during major version upgrades of PostgreSQL.
Previously, major version upgrades of PostgreSQL databases meant choosing between using read replicas with stale data or operating at reduced read capacity during the creation of new read replicas, which could take hours. Now, you can have up-to-date read replicas as soon as the upgrade of your primary database instance completes. You can upgrade one major version higher or you can use Multi Major Version Upgrades for PostgreSQL to skip major versions, such as upgrading from PostgreSQL 9.5 to PostgreSQL 12, and your read replicas will be upgraded to match.
Please refer to the major version upgrade documentation in the Amazon RDS User Guide for details on how to perform major version upgrades with read replicas and also any limitations associated with the upgrade process.