A simple nodeJS example using @clickhouse/client

Here is a basic code snippet filemain.ts.

Package.json (place it under ./):

{
  "name": "a simple clickhouse client example",
  "version": "1.0.0",
  "main": "main.js",
  "license": "MIT",
  "devDependencies": {
    "typescript": "^5.3.2"
  },
  "dependencies": {
    "@clickhouse/client": "^0.2.6"
  }
}

Main.ts (place it under ./src):

import { ClickHouseClient, createClient } from '@clickhouse/client'; // or '@clickhouse/client-web'

interface ClickHouseResultSet<T> {
  meta: Meta[];
  data: T[];
  rows: number;
  statistics: Statistics;
}

interface Statistics {
  elapsed: number;
  rows_read: number;
  bytes_read: number;
}

interface Meta {
  name: string;
  type: string;
}

interface Count {
  c: number;
}

//Please replace client connection parameters like`host`
//`username`, `passowrd`, `database` as needed.

const initClickHouseClient = async (): Promise<ClickHouseClient> => {
  const client = createClient({
    host: 'https://FQDN.aws.clickhouse.cloud',
    username: 'default',
    password: 'password',
    database: 'default',
    application: `pingpong`,
  });

  console.log('ClickHouse ping');
  if (!(await client.ping())) {
    throw new Error('failed to ping clickhouse!');
  }
  console.log('ClickHouse pong!');
  return client;
};

const main = async () => {
  console.log('Initialising clickhouse client');
  const client = await initClickHouseClient();

  const row = await client.query({
    query: `SELECT count() AS c FROM system.tables WHERE database='system'`,
  });

  const jsonRow: ClickHouseResultSet<Count> = await row.json();

  console.log(`I have found ${jsonRow.data[0].c} system tables!`);

  await client.close();
  console.log(`👋`);
};

main();

To install the packages, run yarn from ./:

$ yarn
yarn install v1.22.19
[1/4] 🔍  Resolving packages...
[2/4] 🚚  Fetching packages...
[3/4] 🔗  Linking dependencies...
[4/4] 🔨  Building fresh packages...
✨  Done in 0.14s.

execute the code in main.ts from ./ with:

$ npx ts-node src/main.ts

will output:

Initialising clickhouse client
ClickHouse ping
ClickHouse pong!
I have found 120 system tables!
👋