Announcing cross-database queries for Amazon Redshift (preview)
Amazon Redshift now supports the ability to query across databases in a Redshift cluster. With cross-database queries, you can seamlessly query data from any database in the cluster, regardless of which database you are connected to. Cross-database queries can eliminate data copies and simplify your data organization to support multiple business groups on the same cluster. Support for cross-database queries is available on Amazon Redshift RA3 instance types.
Source:: Amazon AWS