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Get Started with Waddler and ClickHouse

This guide assumes familiarity with:
  • dotenv - package for managing environment variables - read here
  • tsx - package for running TypeScript files - read here
  • @clickhouse/client - package for querying your ClickHouse database - read here

Waddler has native support for ClickHouse connections with the @clickhouse/client driver.

Basic file structure

This is the basic file structure of the project.

📦 <project root>
 ├ 📂 src
 │   └ 📜 index.ts
 ├ 📜 .env
 ├ 📜 package.json
 └ 📜 tsconfig.json

Step 1 - Install @clickhouse/client package

npm
yarn
pnpm
bun 
npm i waddler @clickhouse/client dotenv
npm i -D tsx

Step 2 - Setup connection variables

Create a .env file in the root of your project and add your database connection variable:

DATABASE_URL=

Step 3 - Connect Waddler to the database

clickhouse
clickhouse with config
your clickhouse driver
import 'dotenv/config';
import { waddler } from "waddler/clickhouse";

const sql = waddler(process.env.DATABASE_URL!);

Step 4 - Create a table


(async () => {
  await sql.unsafe(`create table users(
    id    Int32,
    name  String,
    age   Int32,
    email String
)
engine = MergeTree
order by id;
  `).command();
})()

Step 5 - Seed and Query the database

Let’s update the src/index.ts file with queries to create, read, update, and delete users

src/index.ts
import 'dotenv/config';
import { waddler } from 'waddler/clickhouse';
  
const sql = waddler(process.env.DATABASE_URL!);

async function main() {
  const user = [
    'John',
    30,
    '[email protected]',
  ];

  await sql`insert into ${sql.identifier('users')} values ${sql.values([[sql.default, ...user]])};`.command();
  console.log('New user created!')

  const users = await sql`select * from ${sql.identifier('users')};`.query();
  console.log('Getting all users from the database: ', users)
  /*
  const users: {
    id: number;
    name: string;
    age: number;
    email: string;
  }[]
  */

  await sql`alter table ${sql.identifier('users')} update age = ${31} where email = ${user[2]};`.command();
  console.log('User info updated!')

  await sql`alter table ${sql.identifier('users')} delete where email = ${user[2]};`.command();
  console.log('User deleted!')
}

main();

Streaming

src/index.ts
import 'dotenv/config';
import { createClient } from '@clickhouse/client';
import { waddler } from 'waddler/clickhouse';

async function main() {
  const client = createClient({ url: process.env.DATABASE_URL! })
  // process.env.DATABASE_URL should look like this: http[s]://<user>:<password>@<host>:<port>/<database>;

	const sql = waddler({ client });

	const stream = sql`select * from ${sql.identifier('users')};`.query().stream();

	console.log('Streaming users one at a time from the database.')
  for await (const user of stream) {
    console.log(user)
    /*
    const user: {
      id: number;
      name: string;
      age: number;
      email: string;
    }
    */		
	}

	await client.close();
}

main();

Step 6 - Run index.ts file

To run any TypeScript files, you have several options, but let’s stick with one: using tsx

You’ve already installed tsx, so we can run our queries now

Run index.ts script

npm
yarn
pnpm
bun 
npx tsx src/index.ts
tips

We suggest using bun to run TypeScript files. With bun, such scripts can be executed without issues or additional settings, regardless of whether your project is configured with CommonJS (CJS), ECMAScript Modules (ESM), or any other module format. To run a script with bun, use the following command:

bun src/index.ts

If you don’t have bun installed, check the Bun installation docs