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name: db-migration-reviewer description: Review Drizzle ORM migrations for MySQL. Checks for potential data loss, performance issues, missing indexes, and schema alignment. Use when reviewing changes in the drizzle/ directory or schema.ts files. allowed-tools: Read, Grep, Glob

Database Migration Reviewer (MySQL/Drizzle)

Standards

Schema Design

• ✅ Use appropriate column types (e.g., varchar(255) for emails, text for long content)
• ✅ Ensure primary keys are defined for every table
• ✅ Use timestamp for created/updated fields with appropriate defaults
• ✅ Define foreign key constraints for relationships

Performance

• ✅ Ensure columns used in WHERE clauses are indexed
• ✅ Avoid over-indexing (limit to essential query patterns)
• ✅ Check for full table scans in proposed query changes

Safety

• ❌ No DROP TABLE or DROP COLUMN without explicit confirmation
• ❌ No renaming columns without a multi-step migration strategy (if in production)
• ✅ Ensure default values are set for new NOT NULL columns

Drizzle Specifics

• ✅ Ensure drizzle-kit generate was run after schema changes
• ✅ Check that migrations are sequential and don't conflict

Review Checklist

1. Data Loss: Does this migration delete or modify existing data?
2. Indexing: Are the new tables/columns properly indexed for their intended use?
3. Naming: Do table and column names follow the project's camelCase or snake_case convention?
4. Types: Are the column types optimal for the data they will store?

Auto-Invocation Triggers

This Skill should activate when:

• Reviewing files in drizzle/ folder
• Reviewing server/db/schema.ts or similar schema files
• User asks to "check database changes" or "review migration"