Database Design

---
name: database-design
description: "Database design principles and decision-making. Schema design, indexing strategy, ORM selection, serverless databases."
risk: safe
source: community
date_added: "2026-02-27"
---

# 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.