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

Use when selecting a database model, reviewing schema relationships and indexes, or assessing a proposed schema with the bundled advisory tools.

Schema helper

scripts/schema_validator.py is a read-only heuristic inventory, not a Prisma or Drizzle parser. Missing schemas, unsupported formats and heuristic-only results return nonzero with passed: false and analysis_complete: false. Use the project-local ORM validator for syntax and type checks; review migration and constraint semantics separately.

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.