055-design-parallel-change

name	055-design-parallel-change
description	Use when a database schema or data-meaning change needs Parallel Change, including expand, migrate, and contract sequencing for column renames, type or data reinterpretation, large-table backfills, relationship-table changes, enum/status transitions, timezone/default changes, and index or uniqueness changes. This should trigger before framework-specific Flyway implementation guidance when deciding whether a migration needs a compatibility window or whether a simpler migration is sufficient. Part of Plinth Toolkit
license	Apache-2.0
metadata	{"author":"Juan Antonio Breña Moral","version":"0.18.0"}

Parallel Change Design

Guide Java Enterprise developers through Parallel Change for database migration scenarios. This is an interactive SKILL.

What is covered in this Skill?

• Deciding whether a database migration needs a compatibility window
• Sequencing database changes as expand, migrate, and contract deployable steps
• Preserving old and new application versions during rollout and rollback windows
• Handling column renames, type or data reinterpretation, large backfills, relationship-table changes, and index or uniqueness changes
• Explaining tradeoffs such as temporary dual paths, extra migrations, verification effort, and delayed cleanup
• Routing framework-specific implementation to Spring Boot, Quarkus, or Micronaut Flyway skills after the design approach is clear

Constraints

Use Parallel Change as a database migration design pattern, then hand off implementation details to the framework-specific migration skill when needed.