Clickhouse Hello World

What it does

When your agent uses it

• Starting a new ClickHouse project
• Learning MergeTree basics
• Testing your ClickHouse connection with real operations
• With clickhouse hello world

Example prompts

• “clickhouse hello world”
• “first clickhouse table”
• “clickhouse quick start”
• “/clickhouse-hello-world”

Requirements

• Docker
• Compatibility (from SKILL.md): Designed for Claude Code
• Pre-approved tools (allowed-tools): Read, Write, Edit, Bash(npm:*), Bash(node:*)

Workflow steps

4 steps, taken from the step headings in SKILL.md.

1. 1Create a MergeTree Table
2. 2Insert Data with JSONEachRow
3. 3Query the Data
4. 4Explore System Tables (optional)

What it can do on your machine

Read from SKILL.md and the folder at commit cfae287. It shows what the files ask for, not the result of running them.

• Tool permissions

  Pre-approves these tools, so the agent can use them without asking each time:

  • Read
  • Write
  • Edit
  • Bash(npm:*)
  • Bash(node:*)

  From allowed-tools in the SKILL.md frontmatter.

• Runs code

  No scripts in the folder and no shell commands in SKILL.md (its code samples are typescript).

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

• Network

  Links to these hosts (documentation or services it may open):

  • clickhouse.com

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

• Credentials

  Names these keys or tokens, usually read from environment variables:

  • CLICKHOUSE_PASSWORD

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

• Compatibility

  Designed for Claude Code

  From compatibility in the SKILL.md frontmatter.

Context cost

Clickhouse Hello World loads about 1.5k tokens when it runs, and up to ~2.2k if it reads all its reference files. Until then it costs about 93 tokens; SKILL.md has 365 words of instructions outside code blocks.

Always · name and description, kept in context so the agent knows when to use it

~93

When it runs · the whole SKILL.md, loaded when a task matches

~1.5k

With references · SKILL.md plus every file in references/, read only if the agent opens them

~2.2k

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

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

The full file from jeremylongshore/tons-of-skills-marketplace at commit cfae287, republished under its MIT licence (© jeremylongshore). 365 words, ~1,457 tokens.

name

clickhouse-hello-world

description

Create your first ClickHouse table, insert data, and run analytical queries. Use when starting a new ClickHouse project, learning MergeTree basics, or testing your ClickHouse connection with real operations. Trigger with "clickhouse hello world", "first clickhouse table", "clickhouse quick start", "create clickhouse table", "clickhouse example".

allowed-tools

Read, Write, Edit, Bash(npm:*), Bash(node:*)

compatibility

Designed for Claude Code

version

1.7.0

license

MIT

author

Jeremy Longshore <jeremy@intentsolutions.io>

tags

saas, database, analytics, clickhouse, olap

import { createClient } from '@clickhouse/client';

const client = createClient({
  url: process.env.CLICKHOUSE_HOST ?? 'http://localhost:8123',
  username: process.env.CLICKHOUSE_USER ?? 'default',
  password: process.env.CLICKHOUSE_PASSWORD ?? '',
});

await client.command({
  query: `
    CREATE TABLE IF NOT EXISTS events (
      event_id    UUID DEFAULT generateUUIDv4(),
      event_type  LowCardinality(String),
      user_id     UInt64,
      payload     String,
      created_at  DateTime DEFAULT now()
    )
    ENGINE = MergeTree()
    ORDER BY (event_type, created_at)
    PARTITION BY toYYYYMM(created_at)
    TTL created_at + INTERVAL 90 DAY
  `,
});
console.log('Table "events" created.');

await client.insert({
  table: 'events',
  values: [
    { event_type: 'page_view', user_id: 1001, payload: '{"url":"/home"}' },
    { event_type: 'click',     user_id: 1001, payload: '{"button":"signup"}' },
    { event_type: 'page_view', user_id: 1002, payload: '{"url":"/pricing"}' },
    { event_type: 'purchase',  user_id: 1002, payload: '{"amount":49.99}' },
    { event_type: 'page_view', user_id: 1003, payload: '{"url":"/docs"}' },
  ],
  format: 'JSONEachRow',
});
console.log('Inserted 5 events.');

// Count events by type
const rs = await client.query({
  query: `
    SELECT
      event_type,
      count()          AS total,
      uniqExact(user_id) AS unique_users
    FROM events
    GROUP BY event_type
    ORDER BY total DESC
  `,
  format: 'JSONEachRow',
});

const rows = await rs.json<{
  event_type: string;
  total: string;        // ClickHouse returns numbers as strings in JSON
  unique_users: string;
}>();

for (const row of rows) {
  console.log(`${row.event_type}: ${row.total} events, ${row.unique_users} users`);
}

page_view: 3 events, 3 users
click: 1 events, 1 users
purchase: 1 events, 1 users

© jeremylongshore, MIT. Rendered from Markdown: HTML in the file is shown as text, images as links, and headings moved down two levels. Raw file

Files

SKILL.md and 2 other files (references) in skills/.curated/clickhouse-hello-world of jeremylongshore/tons-of-skills-marketplace.

• SKILL.md
• references/mergetree-and-types.md
• references/system-tables.md

Open the folder on GitHubat commit cfae287