Database Design

> Learn to THINK, not copy SQL patterns.

🎯 Selective Reading Rule

Read ONLY files relevant to the request! Check the content map, find what you need.

| File | Description | When to Read | |------|-------------|--------------| | database-selection.md | PostgreSQL vs Neon vs Turso vs SQLite | Choosing database | | orm-selection.md | Drizzle vs Prisma vs Kysely | Choosing ORM | | schema-design.md | Normalization, PKs, relationships | Designing schema | | indexing.md | Index types, composite indexes | Performance tuning | | optimization.md | N+1, EXPLAIN ANALYZE | Query optimization | | migrations.md | Safe migrations, serverless DBs | Schema changes |

⚠️ Core Principle

• ASK user for database preferences when unclear
• Choose database/ORM based on CONTEXT
• Don't default to PostgreSQL for everything

Decision Checklist

Before designing schema:

• ] Asked user about database preference?
• ] Chosen database for THIS context?
• ] Considered deployment environment?
• ] Planned index strategy?
• ] Defined relationship types?

Anti-Patterns

❌ Default to PostgreSQL for simple apps (SQLite may suffice) ❌ Skip indexing ❌ Use SELECT in production ❌ Store JSON when structured data is better ❌ Ignore N+1 queries

When to Use

This skill is applicable to execute the workflow or actions described in the overview.

Limitations

• Use this skill only when the task clearly matches the scope described above.
• Do not treat the output as a substitute for environment-specific validation, testing, or expert review.
• Stop and ask for clarification if required inputs, permissions, safety boundaries, or success criteria are missing.