Security techniques for cross database access

Separation of data from procedures, functions and views is a common approach to protect data. If you deal with microservice architecutres you will quite often separate the "master data" from service data but need to have access to it. What is the best practice to grant access to these data? I will show you three common scenarios for discussion: - Synonyms for remote data - signed procedures - TRUSTWORTHY options to access data What do you think? What is the best approach to deal with these requirements? In this session you learn the pro and the cons of each solution.