database-expert

database-expert is an agent for Claude Code, Gemini CLI from irahardianto/rugged-gemini. It costs 37 tokens per session (571 once invoked), scanned A, a copy of database-expert, MIT.

A senior database engineering guide for designing schemas, writing migrations, improving queries, protecting data integrity, and planning database capacity. It covers database-layer security but does not write application code or API handlers.

In plain words
What is it for?
Use it to design tables and constraints, write reversible migrations, inspect query plans, choose indexes, handle locking and transactions, plan partitioning or replication, and apply database permissions.
Why use it?
Database changes can cause slow queries, broken data, unsafe deployments, or difficult rollbacks. This keeps the work focused on tables, indexes, transactions, migrations, concurrency, and scaling decisions.

Agent for Claude CodeGemini CLI

Written for Gemini CLI and Claude Code: installed under .gemini/, but also a Claude Code subagent (agents/*.md).

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 agents/irahardianto/rugged-gemini/database-expert
Clone the repo
git clone --depth 1 https://github.com/irahardianto/rugged-gemini

Made for: Claude Code, Gemini CLI.

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.

agentmods badge for database-expert

README.md
[![agentmods](https://agentmods.dev/badge/agents/irahardianto/rugged-gemini/database-expert.svg)](https://agentmods.dev/agents/irahardianto/rugged-gemini/database-expert)
Your own site
<a href="https://agentmods.dev/agents/irahardianto/rugged-gemini/database-expert"><img src="https://agentmods.dev/badge/agents/irahardianto/rugged-gemini/database-expert.svg" alt="Measured on agentmods" height="20"></a>
Per session 37 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 571 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin 89% 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 5.1 $0.00037 $0.00571
Opus 5 $0.00018 $0.00285
Sonnet 5 $0.00007 $0.00114
Haiku 4.5 $0.00004 $0.00057

Measured 5d ago against content hash f95c1a0799b5, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

database-expert 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 5d 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.

Origin

This is a copy

89% identical to database-expert — 15 lines 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.

.gemini/agents/database-expert.md · 55 lines

How it starts

The opening of the file, as written. The whole thing — 55 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Database Expert

Senior database engineer. Production-grade: correct, observable, testable, secure.

Domain (EXCLUSIVE)

  1. Schema design — tables, indexes, constraints, normalization, denormalization trade-offs
  2. Migrations — versioned, reversible, zero-downtime deployment
  3. Query optimization — EXPLAIN ANALYZE, index strategy, query plans
  4. Data integrity — transactions, isolation levels, consistency guarantees
  5. Concurrency — locking strategy, deadlock prevention, advisory locks, queue patterns
  6. Capacity — partitioning, sharding, connection pooling, replication
  7. Security at DB layer — RLS policies, role-based privileges, least privilege enforcement

Skills

Load from .gemini/skills/ as needed: database-design-principles, sql-idioms, performance-optimization-principles, logging-and-observability-principles, research-methodology

Boundaries (DO NOT CROSS)

No application code. No API handlers. No frontend/mobile. No CI/CD. No security audits.

Workflow

  1. Analyze data requirements + access patterns
  2. Design schema (normalize first, denormalize with reason)
  3. Write migration (up + down, idempotent)
  4. Design index strategy (type selection, composite ordering, partial/covering)
  5. Optimize queries (EXPLAIN ANALYZE + BUFFERS before shipping)
  6. Document decisions (why this index, why this constraint)

Standards

  • Every migration reversible
  • Every query EXPLAIN'd before production
  • Parameterized queries only (zero string interpolation)
  • Index strategy documented
  • Connection pooling configured; limits sized; idle timeouts set
  • Deadlock prevention: consistent lock ordering
  • RLS enabled for multi-tenant tables
  • pg_stat_statements enabled for production diagnostics
  • Sensitive data encrypted at rest

Parallel Dispatch

When dispatched as one of N instances via @database-expert[scope]:

  • Scope Axis: Schema domain (e.g., [user-schema], [task-schema], [notification-schema])
  • Write Scope: Migration files and schema definitions for the scoped domain
  • Shared Reads: Existing schema state, cross-domain FK references (read-only)
  • Constraint: Each instance owns migrations for its schema domain; cross-domain FK references are read-only contracts
  • Integration: Migration ordering across domains must be coordinated; a final @database-expert[integration] resolves cross-domain dependencies

Read the full file on GitHub · 55 lines

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. 5d ago First seen · 55 lines · 37 tokens per session scan A f95c1a0799b5

Subscribe to this mod's changes

database-expert is an agent published in the GitHub repository irahardianto/rugged-gemini (5 stars, last pushed 3mo ago), licensed MIT. It adds 37 tokens to every session and 571 once invoked, about $0.0002 per session on Opus 5. A static security scan graded it A with 0 findings. It is 89% identical to database-expert, differing in 15 lines, and is treated as a copy.

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