Architecting a multi-tenanted application is challenging. Decisions can impact developers and operations for the life of the application, which is measured in years, if not for over a decade.

Often, the hardest decision is which of the three common multi-tenancy architecture approaches is appropriate. A unique application and database per tenant, shared application and isolated database per tenant, or shared application and database. This decision is so challenging because there is no "one true approach." Each application's scenario is different.

I've witnessed the impact of those decisions firsthand. I've been exposed to each approach during my career as a software developer and architect. I spent over 20 years supporting six different multi-tenanted applications for companies working in advertising, telemarketing, oil, finance, government, and software.

In this session, we will walk through the lessons learned from working on those applications.

In this talk, attendees will learn:
- The pros and cons of each approach; unique application and database per tenant, shared application and isolated database per tenant, and shared application and database.
- When one approach is preferred over the other.
- How to handle unique configurations and requirements per tenant.
- The hidden costs and the long-term impacts.
- How advancements in tooling and platforms have made the unique application and database per tenant easier to support.

The target audience for this talk is architects, developers, and people in operations. The session is best for someone who has been in the IT industry for 1-2 years.