blake-john/agent-config/architecture-designer

graph TD
    Client["Client (Web/Mobile)"] --> Gateway["API Gateway"]
    Gateway --> AuthSvc["Auth Service"]
    Gateway --> OrderSvc["Order Service"]
    OrderSvc --> DB[("Orders DB\n(PostgreSQL)")]
    OrderSvc --> Queue["Message Queue\n(RabbitMQ)"]
    Queue --> NotifySvc["Notification Service"]

# ADR-001: Use PostgreSQL for Order Storage
 
## Status
Accepted
 
## Context
The Order Service requires ACID-compliant transactions and complex relational queries
across orders, line items, and customers.
 
## Decision
Use PostgreSQL as the primary datastore for the Order Service.
 
## Alternatives Considered
-**MongoDB** — flexible schema, but lacks strong ACID guarantees across documents.
-**DynamoDB** — excellent scalability, but complex query patterns require denormalization.
 
## Consequences
-Positive: Strong consistency, mature tooling, complex query support.
-Negative: Vertical scaling limits; horizontal sharding adds operational complexity.
 
## Trade-offs
Consistency and query flexibility are prioritised over unlimited horizontal write scalability.