Read-only replica of RDS Postrgres instance with modified schema We have a Postgres instance hosted in Amazon RDS. The idea is to create some kind of a read-only replica for a separate application. This application requires some modifications of the DB schema - additional indexes, denormalization, etc.

What is the common practice to achieve such goals?
You can't do this in RDS at the moment. You can spin a replica as a mirrored database but it does not allow the advanced features for logical decoding or partial replication. Unfortunately this is the caveat on the AWS services. The best option will be to move out RDS to EC2.