database-design

Guidance for choosing a database, organizing its tables and relationships, adding indexes, selecting an ORM, and changing the schema safely. An ORM is a tool that lets code work with database data without writing every SQL query by hand.

In plain words
What is it for?
Use it when selecting PostgreSQL, Neon, Turso, or SQLite; comparing Drizzle, Prisma, or Kysely; designing tables; planning indexes; improving queries; or preparing migrations, which are controlled database structure changes.
Why use it?
It helps avoid choosing a database or ORM by habit, poorly structured tables, slow queries, and risky schema changes. It also prompts decisions based on the application and where it will run.

Skill for Claude CodeCodex

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/felipeslo/opencode-kit/database-design
Any agent
npx skills add felipeslo/opencode-kit --skill database-design
Clone the repo
git clone --depth 1 https://github.com/felipeslo/opencode-kit

Made for: Claude Code, Codex.

Per session 23 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 337 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 94% copy Near-identical to another mod in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5 $0.00023 $0.00337
Opus 5 $0.00012 $0.00169
Sonnet 5 $0.00005 $0.00067
Haiku 4.5 $0.00002 $0.00034

Measured yesterday against content hash 23846ce80caf, method: parsed. Prices are Anthropic first-party input rates as of 2026-08-30, from the pricing page.

Security

Grade A, and why

database-design scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured yesterday.

The scan reads SKILL.md. This mod also ships 1 executable file (scripts/schema_validator.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

This is a copy

94% identical to database-design — 1 line differ, which has more behind it and is treated as the original. This page carries a canonical link to it rather than competing with it.

.opencode/skills/database-design/SKILL.md · 52 lines

What it actually says

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

Files

What ships with it

7 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. yesterday First seen · 52 lines · 23 tokens per session scan A 23846ce80caf

Subscribe to this mod's changes

database-design is a skill published in the GitHub repository felipeslo/opencode-kit (2 stars, last pushed 5mo ago), licensed MIT. It adds 23 tokens to every session and 337 once invoked, about $0.0001 per session on Opus 5. A static security scan graded it A with 0 findings. It is 94% identical to database-design, differing in 1 line, and is treated as a copy.

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