A guide for production database work involving PostgreSQL or MongoDB, systems used to store and query application data. It covers schemas, models, migrations, queries, indexes, connections, and backups.

Use it when creating, changing, or reviewing database schemas, models, migrations, queries, indexes, transactions, connection settings, backups, or performance.

It reduces the risk of inconsistent database changes, slow queries, broken migrations, or unsafe production assumptions.

databases — Skill for Claude Code and Codex by tamnguyendinh/Anvien

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.

Any agent

npx skills add tamnguyendinh/Anvien --skill databases

Clone the repo

git clone --depth 1 https://github.com/tamnguyendinh/Anvien

Made for: Claude Code, Codex.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

README.md

[![agentmods](https://agentmods.dev/badge/skills/tamnguyendinh/anvien/databases/github.svg)](https://agentmods.dev/skills/tamnguyendinh/anvien/databases)

Your own site

<a href="https://agentmods.dev/skills/tamnguyendinh/anvien/databases"><img src="https://agentmods.dev/badge/skills/tamnguyendinh/anvien/databases/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

Your own site · 80×15

<a href="https://agentmods.dev/skills/tamnguyendinh/anvien/databases"><img src="https://agentmods.dev/badge/skills/tamnguyendinh/anvien/databases.svg" alt="Reviewed on agentmods" width="80" height="20"></a>

Per session 74 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.

When invoked 1,516 The whole file, excluding the scripts and references it only reads on demand.

Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.

Origin original No closer match found 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.

Model	Per session	Once invoked
Fable 5.1	$0.00074	$0.01516
Opus 5.5	$0.00030	$0.00606
Sonnet 5.5	$0.00015	$0.00303
Haiku 4.5	$0.00007	$0.00152

Measured 1mo ago against content hash 78e261784909, method: parsed. Prices are Anthropic first-party input rates as of 2026-10-07, from the pricing page.

Security

Grade A, and why

databases 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 1mo ago.

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.

internal/aicontext/skills/databases/SKILL.md · 109 lines

How it starts

The opening of the file, as written. The whole thing — 109 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Databases Skill

Repo-first guidance for creating, changing, and reviewing MongoDB, PostgreSQL, or SQLite database work in real repositories.

Purpose

Use this skill when the task involves database schema, models, migrations, queries, indexes, transactions, seed data, connection config, backup/restore assumptions, or database performance.

The goal is not to teach basic database syntax. The goal is to help the agent produce database work that is correct, production-ready, and consistent with the target repository.

Core Rule

Follow the user's requested action.

If the user asks for review, review. If the user asks for a plan, plan. If the user asks for implementation, implementation is allowed.

In every mode, database work must meet the production database bar unless the user explicitly asks for a throwaway prototype.

Repo-First Rule

Before proposing or editing database work, inspect the target repository first:

Database engine and version
ORM, query builder, or data-access layer
Migration framework and migration conventions
Existing schema, model, index, and query patterns
Connection config and environment conventions
Tests, seed data, fixtures, and deployment assumptions

Follow repo-native tooling and patterns unless there is a clear reason not to.

Production Database Bar

Production-ready database work must account for:

Correctness: constraints, nullability, uniqueness, referential rules, validation, and ownership boundaries.
Migration safety: forward path, rollback or mitigation path, deploy order, locking risk, data volume, and backfill behavior.
Performance: expected queries, indexes, cardinality, pagination, aggregation cost, and query plans where relevant.
Concurrency: transaction boundaries, isolation assumptions, duplicate writes, retries, and out-of-order events.
Security: least privilege, secret handling, PII, encryption assumptions, and auditability.
Operations: backup/restore assumptions, monitoring, slow-query visibility, retention, and failure recovery.
Repo fit: existing ORM, migration framework, naming, config, and test patterns.

Read the full file on GitHub · 109 lines

Files

What ships with it

12 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.

1mo ago Changed · +4 lines 78e261784909
2mo ago Changed · +2 lines · +8 tokens per session 01bbc7311355
2mo ago First seen · 103 lines · 66 tokens per session scan A 3c1b5d2f9f8a

Subscribe to this mod's changes

databases is a skill published in the GitHub repository tamnguyendinh/Anvien (12 stars, last pushed 4d ago), licensed MIT. It adds 74 tokens to every session and 1,516 once invoked, about $0.0003 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-31.

Databases MongoDB PostgreSQL ai-agents code-intelligence-mcp dead-code-detection developer-tools graph-database graph-visualization

databases next to 6 skills from other repositories
Mod	Type	Stars	Last push	Licence	Scan	Tokens	Works with
databasestamnguyendinh/Anvien	Skill	12	4d ago	MIT	A	74	Claude Code, Codex
ring:mapping-service-resourcesLerianStudio/ring	Skill	218	6d ago	Apache-2.0	A	97	Cursor
fastapi-init-skilljiushiwon/wg-skills	Skill	134	yesterday	Apache-2.0	A	229	Claude Code, Codex
database-experttravisjneuman/.claude	Skill	107	yesterday	MIT	A	36	Claude Code, Codex
agent-database-experttravisjneuman/.claude	Skill	107	yesterday	MIT	A	49	Claude Code
database-migratorOneWave-AI/claude-skills	Skill	415	18d ago	MIT	A	76	Claude Code
database-schema-designerOneWave-AI/claude-skills	Skill	415	18d ago	MIT	A	141	Claude Code, Codex