Database Access
Data sharing is not a good situation for microservices. A microservice should be designed to have exclusive database control. If data sharing is required among different databases, it should preferably be achieved by leveraging the database internal processes.
For example, a customer service should offer all customer functionality and should have exclusive access to customer data (table or set of tables). All other services, requiring access to customer data, should get the data via the Customer Service (which is a microservice here). No other service should get exclusive access to the customer data table or set of tables.