can anyone elaborate on the difference between AWS Read Replica and readable Standby instances which AWS has offered recently?
>Solution :
I assume you’re talking about the Readable Standby Instances available in Preview at the time of writing this.
Compared to the traditional read replicas, the main difference is the kind of replication involved. Replication to read replicas happens asynchronously. That means read replicas aren’t necessarily up to date with the main database. This is something your workload needs to be able to deal with if you want to use that.
Readable standby instances on the other hand use synchronous replication. When you read from one of those instances your data will be up to date.
There are also a couple of other differences between the capabilities, but some things aren’t finalised yet. The main difference is the kind of replication.