Microservices: The Data Ownership Trap¶

Microservices promise agility and scalability, but there's a hidden pitfall that can derail your chosen architecture: shared data.

The Silent Killer: Shared Tables¶

Splitting your application into services isn't enough. If your services are still reaching into shared database tables, you're not building a true microservices architecture.

Red Flags to Watch Out For:¶

Direct table access across services
Pseudo-independent copies of tables within the same operational system
Triggers creating bottlenecks on shared tables
Legacy stored procedures spanning multiple services
The dangerous "we'll fix it later" mentality

The Fundamental Principle: Data Sovereignty¶

While there are exceptions, sharing tables across two or more microservices will create a tangled web of dependencies.

The Path to True Microservices:¶

Strict data ownership: Each service manages its own data.
API-first communication: Services interact via APIs, not direct database access.
Team alignment: Organize teams to match architectural boundaries (hello, Conway's Law!).

The Bottom Line¶

Good data design always included clear boundaries around data access; this was equally true with monoliths.

Things you might have gotten away with before, though … like direct data access to update a shared table across two services inside a monolith … will not work with microservices.

Microservices are complex. Your data boundaries must be as clear and intentional as your service boundaries.