Medium: PostgreSQL 18 in Microservices: You Don’t Need a Separate DB for Everything

Microservices architecture promotes independence: services should be loosely coupled, own their data, and be deployable independently. However, the common belief that every microservice must have its own separate database is a misconception that needs revisiting in 2025.

PostgreSQL 18 introduces powerful features like enhanced concurrent access, asynchronous I/O, row-level security, and logical partitioning. These advancements enable multiple microservices to share a single database without compromising autonomy or security.

The key distinction is between service autonomy and physical data isolation. Autonomy means clear ownership and no accidental coupling, not necessarily separate physical databases. PostgreSQL 18 allows logical separation within one database, preserving boundaries while simplifying management.

Using a single PostgreSQL 18 database can reduce operational complexity and costs. Logical partitioning and row-level security ensure that each service accesses only its own data, maintaining security and performance comparable to separate databases.

Architectural patterns leveraging PostgreSQL 18 include multi-tenant schemas and logical partitions. These patterns allow services to coexist in one database instance, enabling efficient resource use and easier data integration when needed.

Benchmarks from real workloads demonstrate that PostgreSQL 18 handles concurrent access efficiently, supporting multiple microservices with minimal latency impact. Async I/O further improves throughput, making shared databases viable for scalable microservices.

Choosing between separate databases and a consolidated PostgreSQL 18 setup depends on trade-offs like operational overhead, data coupling risk, and performance needs. For many scenarios, PostgreSQL 18 offers a balanced approach that preserves service independence without fragmentation.