I would like to have your opinion and your feedback on the implementation of a Multi-instance (Single-tenant) or Multi-tenant architecture with a database by tenant, at the level of data sharing between tenant.

Imagine two clients who each have an instance of the same application and therefore each have a separate database.

  A third client also connects to its instance, but in addition, it must be able to read and / or write certain data at client 1 and / or client 2.

What are the possibilities to allow such data sharing in an architecture as described above?

And second scenario, if we have 100 tenants, therefore 100 databases, and if I need global analysis functionality, I must request each of these 100 databases to have the complete information?

Thank you for your answers.

I would like to know which architecture is more suitable when considering data sharing between tenants: a Multi-instance (Single-tenant) or Multi-tenant architecture with a database by tenant.

Imagine this first scenario with two clients who each having an instance of the same application and therefore each have a separate database. A third client also connects to its instance, but in addition, it must be able to read and / or write certain data at client 1 and / or client 2.

What are the possibilities to allow such data sharing in an architecture as described above?

And second scenario, if we have 100 tenants, therefore 100 databases, and if I need global analysis functionality, do I have to query each of these 100 databases to have the complete information?