I'm testing this for possible application and I'm getting an unexpected error.
"An error occurred (BadRequestException) when calling the ExecuteSql operation: ERROR: invalid cluster id: arn:aws:rds:us-etc."
The documentation states that "-db-cluster-or-instance-arn (string) ARN of the target db cluster or instance"
That is an RDS instance arn that it is rejecting as a cluster id. The arn is a valid id for an RDS instance.
Is it unable to differentiate between cluster id's and instance arns without some kind of additional flag?