database-design

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 |

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⚠️ Core Principle

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

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Decision Checklist

Before designing schema:

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

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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.