Amazon Redshift Spectrum - allows you to ONLY query data on S3
Amazon Redshift Federated Query - allows you to query data on other databases and ALSO S3.
So, if we are querying S3, the query we execute is exactly same in both cases:
Select * from my-schema.my_table
Where my-schema is External Schema in Glue Data Catalog, pointing to data in S3
Therefore, when querying S3 - how does Redshift decide whether it must use Spectrum or Federated Query engine? Is the underlying engine same for both - when querying S3?
