313-frameworks-spring-db-migrations-flyway

# Spring — Database migrations (Flyway)

Apply Flyway migration guidelines for Spring Boot.

**What is covered in this Skill?**

- flyway-core and database-specific Flyway modules (e.g. PostgreSQL) with Spring Boot BOM
- Versioned SQL under `src/main/resources/db/migration` (`V{version}__{description}.sql`)
- `spring.flyway.*` properties: locations, baseline-on-migrate, validate-on-migrate
- Optional Java migrations (`BaseJavaMigration`) for data backfills
- Forward-only discipline: do not rewrite applied migrations in shared environments
- Parallel Change as the safe expand, migrate, contract workflow for breaking or data-sensitive schema changes
- Coordination with `@311-frameworks-spring-jdbc` and `@312-frameworks-spring-data-jdbc`

**Scope:** Apply recommendations based on the reference rules and good/bad examples.

## Constraints

Before applying Flyway or SQL changes, ensure the project compiles. After improvements, run full verification.

- **MANDATORY**: Run `./mvnw compile` or `mvn compile` before applying any change
- **SAFETY**: If compilation fails, stop immediately
- **VERIFY**: Run `./mvnw clean verify` or `mvn clean verify` after applying improvements
- **BEFORE APPLYING**: Read the reference for detailed rules and good/bad patterns
- **BREAKING CHANGE REVIEW**: Before recommending or applying a migration, assess whether it can break deployed application versions, dependent services, reports, jobs, or production data interpretation; if yes, require explicit human review before proceeding
- **EDGE CASE**: If the user goal is ambiguous, stop and ask a clarifying question before editing files or running project-wide commands
- **EDGE CASE**: If required context, files, credentials, or tools are missing, report the blocker explicitly and ask whether to proceed with setup or fallback guidance
- **EDGE CASE**: If requested changes conflict with project constraints or safety boundaries, explain the conflict and ask for user confirmation on the preferred trade-off

## When to use this skill

- Add or review Flyway migrations in a Spring Boot project
- Configure spring.flyway or db/migration layout
- Add versioned Flyway SQL migrations for Spring Boot
- Review Spring Boot database migration ordering
- Fix repeatable Flyway migrations in a Spring project

## Workflow

1. **Read references and assess project context**

Read `references/313-frameworks-spring-db-migrations-flyway.md`, `references/313-frameworks-spring-db-migrations-flyway-antipatterns.md`, and `references/313-frameworks-spring-db-migrations-flyway-parallel-change.md`, then inspect the current project setup before proposing changes.

2. **Gather scope and decide target improvements**

Identify requested outcomes, constraints, and the minimum safe set of changes to apply.

3. **Apply framework-aligned changes**

Implement or refactor configuration/code following the reference patterns and project conventions. Use Parallel Change (expand, migrate, contract) as the safe default for breaking or data-sensitive schema changes.

4. **Run verification and report results**

Execute appropriate build/tests and summarize what changed, what was verified, and any follow-up actions.

## Reference

For detailed guidance, examples, and constraints, see:

- [references/313-frameworks-spring-db-migrations-flyway.md](references/313-frameworks-spring-db-migrations-flyway.md)
- [references/313-frameworks-spring-db-migrations-flyway-antipatterns.md](references/313-frameworks-spring-db-migrations-flyway-antipatterns.md)
- [references/313-frameworks-spring-db-migrations-flyway-parallel-change.md](references/313-frameworks-spring-db-migrations-flyway-parallel-change.md)