ADR 0004: Use Flyway and PostgreSQL

Status

Accepted

Context

The project should demonstrate production persistence discipline. Letting Hibernate update schemas automatically hides important database changes and makes CI less representative of production.

Decision

Use PostgreSQL as the primary relational database and Flyway for all schema changes. Hibernate validates the schema with ddl-auto=validate.

Consequences

Benefits:

• database changes are reviewed as versioned artifacts
• CI catches entity/schema drift
• local development matches production-style behavior

Trade-offs:

• every schema change requires a migration
• tests need PostgreSQL, provided by Testcontainers
• developers must understand both JPA mappings and SQL migrations