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Agent skill

Query Engine Design

by revfactory in revfactory/claude-code-harness

SQL query engine design and implementation guide. An agent skill from revfactory/claude-code-harness.

No licenceAuto-check passedDatabases

Install Query Engine Design

skills CLI
$ npx skills add revfactory/claude-code-harness --skill query-engine-design -a claude-code

Project install by default; add -g for ~/.claude/skills/.

GitHub CLI
$ gh skill install revfactory/claude-code-harness query-engine-design --agent claude-code

Project scope by default; add --scope user for a personal install. Needs GitHub CLI 2.90.0 or later (public preview).

Manual copy
$ git clone --depth 1 https://github.com/revfactory/claude-code-harness.git skills-src && mkdir -p .claude/skills && cp -r skills-src/experiments/results/case-009/harness/.claude/skills/query-engine-design .claude/skills/query-engine-design && rm -rf skills-src

Use ~/.claude/skills/ instead of .claude/skills for a personal install. The folder must contain SKILL.md.

Claude Code skills documentation · loads skills from .claude/skills/

Facts

Skill name
query-engine-design
GitHub stars
120
Token cost
~474 tokens
SKILL.md length
168 words
Files
3 (incl. references)
Skills in repo
15
Repo updated
First seen
Licence
None found

At a glance

SQL query engine design and implementation guide. An agent skill from revfactory/claude-code-harness.

  • Works in 3 steps: Parser: SQL 문자열을 AST로 변환 (재귀 하강) → Planner: 논리적 실행 계획 → 물리적 실행 계획 → Executor: 실행 계획을 순회하며 결과셋 생성
  • The user requests building a SQL engine
  • SKILL.md covers 3단계 파이프라인 워크플로우, SQL 지원 범위 (우선순위), NULL 3값 로직 규칙 and 파일 구조, plus 2 more sections
  • Instructions only: no scripts, shell commands, URLs or credentials in SKILL.md

What it does

Query Engine Design is an agent skill from revfactory/claude-code-harness. SQL query engine design and implementation guide. Use when the user requests building a SQL engine, query parser, query planner, or query executor — including in-memory storage, SQL parsing, and query optimization.

Its SKILL.md is about 470 tokens, which your agent loads only when the skill is triggered. The skill folder holds 3 other files, including reference files (for example `references/executor-patterns.md` and `references/sql-parser.md`).

It sits in Databases, covering SQL and Query optimization. It works with SQL.

When your agent uses it

  • The user requests building a SQL engine
  • Query executor — including in-memory storage
  • Query optimization

Example prompts

  • “/query-engine-design”

Workflow steps

3 steps, taken from the first numbered list in SKILL.md.

  1. Parser: SQL 문자열을 AST로 변환 (재귀 하강)
  2. Planner: 논리적 실행 계획 → 물리적 실행 계획
  3. Executor: 실행 계획을 순회하며 결과셋 생성

What it can do on your machine

Read from SKILL.md and the folder at commit 267005c. It shows what the files ask for, not the result of running them.

  • Tool permissions

    Pre-approves nothing: there is no allowed-tools line, so your agent's usual permission prompts apply.

    From allowed-tools in the SKILL.md frontmatter.

  • Runs code

    No scripts in the folder and no shell commands in SKILL.md.

    From the folder's file list and the shell code blocks in SKILL.md.

  • Network

    No URLs in SKILL.md.

    From URLs in SKILL.md, links to its own repository left out.

  • Credentials

    Names no API keys, tokens, secrets or passwords.

    From names ending in _API_KEY, _TOKEN, _SECRET, _KEY or _PASSWORD in SKILL.md.

Context cost

Query Engine Design loads about 474 tokens when it runs, and up to ~1.4k if it reads all its reference files. Until then it costs about 59 tokens; SKILL.md has 168 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it
~59
When it runs · the whole SKILL.md, loaded when a task matches
~474
With references · SKILL.md plus every file in references/, read only if the agent opens them
~1.4k

Estimates: characters ÷ 4, the usual rule of thumb; real counts depend on the model's tokenizer. Scripts and assets cost tokens only if the agent reads them.

Safety

Auto-check passed

The automated check found no risky patterns in SKILL.md.

Automated static check — not a guarantee. Review scripts before installing. It scans the text of SKILL.md for risky patterns (piping downloads into a shell, reading credential files, hidden Unicode, destructive commands); files beside SKILL.md are not scanned.

SKILL.md

Without a licence we can't republish the file, so here is its outline and opening line. It has 168 words (~474 tokens).

“SQL 쿼리 엔진 설계 및 구현 가이드”

— opening of SKILL.md by revfactory
name
query-engine-design

Read the full SKILL.md on GitHub

Files

SKILL.md and 2 other files (references) in experiments/results/case-009/harness/.claude/skills/query-engine-design of revfactory/claude-code-harness.

  • SKILL.md
  • references/executor-patterns.md
  • references/sql-parser.md

Open the folder on GitHubat commit 267005c

Compare with similar skills

Query Engine Design next to the 5 skills that share the most tags, products or categories with it. Stars are the repository's; “used in” counts other GitHub owners with a copy.

Query Engine Design compared with similar skills
SkillStarsUsed inTokensAuto-checkLicenceRepo updated
Query Engine Design this skillrevfactory/claude-code-harness120—~474Automated safety check: PassNone
SQL Optimization Patternsynulihao/AgentSkillOS61711 repos~3.3kAutomated safety check: PassNone
SQL Optimization Patternssickn33/agentic-awesome-skills47k1 repos~566Automated safety check: PassMIT
SQL Database Assistantborghei/Claude-Skills881—~1.5kAutomated safety check: PassMIT
SQL Optimization InterviewerPrepLabsAI/InterviewMentor112—~2.1kAutomated safety check: PassMIT
Writing SQLrileyhilliard/claude-essentials130—~627Automated safety check: PassMIT

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Works with

Categories

Questions about Query Engine Design

What does Query Engine Design do?

SQL query engine design and implementation guide. An agent skill from revfactory/claude-code-harness. Query Engine Design is an agent skill from revfactory/claude-code-harness. SQL query engine design and implementation guide.

When should I use Query Engine Design?

Query Engine Design fits situations like: the user requests building a SQL engine; query executor — including in-memory storage; query optimization.

How do I install Query Engine Design in Claude Code?

Run `npx skills add revfactory/claude-code-harness --skill query-engine-design -a claude-code`. Or copy the skill folder (experiments/results/case-009/harness/.claude/skills/query-engine-design in revfactory/claude-code-harness) into .claude/skills/query-engine-design in your project. Claude Code loads it when a task matches its description.

How do I install Query Engine Design in Codex?

Run `npx skills add revfactory/claude-code-harness --skill query-engine-design -a codex`. Or copy the skill folder (experiments/results/case-009/harness/.claude/skills/query-engine-design in revfactory/claude-code-harness) into .agents/skills/query-engine-design in your project. Codex loads it when a task matches its description.

Can I use Query Engine Design in Cursor, Gemini CLI or GitHub Copilot?

Cursor, Gemini CLI, GitHub Copilot and OpenCode also load SKILL.md folders. With the skills CLI, run `npx skills add revfactory/claude-code-harness --skill query-engine-design -a cursor` (or -a gemini-cli, github-copilot or opencode for the others). To copy it by hand, put the folder in .cursor/skills/query-engine-design, .gemini/skills/query-engine-design, .github/skills/query-engine-design and .opencode/skills/query-engine-design in your project.

What does Query Engine Design need to run?

SKILL.md names no scripts, command-line tools or credentials: Query Engine Design is instructions for the agent only.

Does Query Engine Design access the network?

SKILL.md contains no URLs. Any network use would come from the scripts or tools the agent runs. This is read from the text; nothing was executed.

Is Query Engine Design safe to install?

Our automated static check of SKILL.md found no risky patterns, such as piping downloads into a shell, reading credential files or hidden Unicode. It is not a guarantee. Review the folder before installing.

What licence does Query Engine Design use?

No licence was found for Query Engine Design or its repository. Without one, default copyright applies: ask the author before reusing or redistributing it.

How many tokens does Query Engine Design use?

About 474 tokens (SKILL.md is roughly 1.9k characters). Agents keep only the skill's name and description in context until a task matches; then they load SKILL.md in full. Its references folder adds about 965 tokens, read only when the agent opens those files.

What are the alternatives to Query Engine Design?

Skills that share tags, products or a category with Query Engine Design: SQL Optimization Patterns (ynulihao/AgentSkillOS, 617 stars), SQL Optimization Patterns (sickn33/agentic-awesome-skills, 47k stars), SQL Database Assistant (borghei/Claude-Skills, 881 stars) and SQL Optimization Interviewer (PrepLabsAI/InterviewMentor, 112 stars). The comparison table on this page puts their stars, adoption, token cost, safety result and licence side by side.

Who maintains Query Engine Design?

revfactory (a GitHub user) maintains it in revfactory/claude-code-harness, which has 120 GitHub stars. The repository holds 15 skills in this directory. The repository was last updated on March 6, 2026.

Source: revfactory/claude-code-harness on GitHub. Facts on this page come from the repository at the commit we read; the author's words are quoted as theirs.