Overview
This lecture discusses the "Sharing the Database" communication pattern between microservices, detailing its advantages, challenges, mitigation strategies, and appropriate use cases.
Sharing the Database Pattern
- Microservices sometimes access and update data directly in each other's database instead of interacting through APIs.
- This approach is called the "Sharing the Database" pattern.
- It enables multiple services to communicate by reading/writing directly to a shared database.
- Example: Both blog and analytics services directly access the same database for updates.
Advantages of Sharing the Database
- Simplifies integration without the need for complex API communication.
- Reduces development time and operational complexity.
- Eliminates latency caused by extra network hops.
- Allows teams to work independently for faster delivery.
- Improves system performance due to direct database access.
Key Challenges of Sharing the Database
- Loss of Data Encapsulation: External teams must understand internal database schemas and implementation details.
- Tight Coupling: Changes in the database schema require all dependent services to update their logic, reducing team autonomy.
- Duplicated Business Logic: Business logic has to be replicated across services, leading to reduced cohesion.
- Data Corruption/Deletion Risks: Multiple services with write access can cause accidental data loss or corruption.
- Resource Contention/Abuse: Heavy or faulty queries by one service can degrade performance for all services sharing the DB.
Mitigation Strategies and Suitable Use Cases
- Use when teams are small, schema changes are rare, or rapid development is needed.
- Apply strict access controls at the table or row level to prevent unauthorized data changes.
- Offload heavy read queries to a replica database to reduce impact on the main service.
- Avoid for systems needing high autonomy or frequent schema evolution.
Key Terms & Definitions
- Microservice — A small, independently deployable service that performs a specific business function.
- Sharing the Database Pattern — A design where multiple microservices read/write directly into a single shared database.
- Tight Coupling — When services depend closely on each other, making independent changes difficult.
- Business Logic — Application-specific rules or logic that define how data is created, displayed, stored, and changed.
- Data Replica — A copy of the primary database used to reduce load or improve fault tolerance.
Action Items / Next Steps
- Review access controls for services using a shared database.
- Consider use cases where schema stability and quick development are priorities before adopting this pattern.
- Explore alternatives for reducing coupling, such as using APIs for inter-service communication.