On Azure SQL Server Stretch Database's Privacy Page you can request and collect all the privacy and GDPR related information that Azure SQL Server Stretch Database is providing.
The privacy policy by is a legal document or statement that discloses how Azure SQL Server Stretch Database gathers, uses, discloses, and manges their customers' data.
The basis for Microsoft sharing, adding, uploading, hosting, accessing or sending personal data out of Europe. Vendors can also add a description of their own impact assessment for data transfers.