Integrating Cloud SQL with Autonomous Database
Autonomous Database supports database links and allows queries to span multiple databases.
Oracle Cloud SQL provides access to its Query Server on a secure Hadoop cluster using a standard Database Connection; it does not require a Kerberized client. In addition to making it easier for clients to connect to Query Server, it also allows other databases, like Autonomous Database, to connect.
You can use database links to query Big Data Service from Autonomous Database.
Although the query from Autonomous Database to Query Server is serial, the Query Server parallelizes the processing against Hadoop data - scanning, filtering, and aggregating data - returning summary information to Autonomous Database.