Get Started with Hasura DDN and DuckDB

Overview

This tutorial takes about twenty minutes to complete. You'll learn how to:

• Set up a new Hasura DDN project
• Connect it to a local DuckDB database
• Generate Hasura metadata
• Create a build
• Run your first query
• Create relationships

Additionally, we'll familiarize you with the steps and workflows necessary to iterate on your API.

This tutorial assumes you're starting from scratch; you'll connect a local DuckDB instance to Hasura, but you can easily follow the steps if you already have data seeded. Hasura will never modify your source schema.

Prerequisites

Install the DDN CLI

macOS and Linux

Simply run the installer script in your terminal:

curl -L https://graphql-engine-cdn.hasura.io/ddn/cli/v4/get.sh | bash

ARM-based Linux Machines

Currently, the CLI does not support installation on ARM-based Linux systems.

Windows

• Download the latest DDN CLI installer for Windows.
• Run the DDN_CLI_Setup.exe installer file and follow the instructions. This will only take a minute.
• By default, the DDN CLI is installed under C:\Users\{Username}\AppData\Local\Programs\DDN_CLI
• The DDN CLI is added to your %PATH% environment variable so that you can use the ddn command from your terminal.

Install Docker

The Docker based workflow helps you iterate and develop locally without deploying any changes to Hasura DDN, making the development experience faster and your feedback loops shorter. You'll need Docker Compose v2.20 or later.

Validate the installation

You can verify that the DDN CLI is installed correctly by running:

ddn doctor

Tutorial

Step 1. Authenticate your CLI

Before you can create a new Hasura DDN project, you need to authenticate your CLI:

ddn auth login

This will launch a browser window prompting you to log in or sign up for Hasura DDN. After you log in, the CLI will acknowledge your login, giving you access to Hasura Cloud resources.

Step 2. Scaffold out a new local project

Next, create a new local project:

ddn supergraph init my-project && cd my-project

Once you move into this directory, you'll see your project scaffolded out for you. You can view the structure by either running ls in your terminal, or by opening the directory in your preferred editor.

Step 3. Initialize your DuckDB connector

In your project directory, run:

ddn connector init my_duckdb -i

From the dropdown, select /hasura/duckdb (you can type to filter the list). Then, enter the following file path:

/etc/connector/data.duckdb

Why this path?

When your DuckDB connector starts as a container, its directory in your project gets mounted. This will make the data.duckdb file accessible to the container and the connector. We'll create this file in the next step.

Step 4. Prepare an initial DuckDB file

Install the DuckDB CLI

You'll need the DuckDB CLI installed on your machine to prepare the database file. You can install it here.

echo "
-- Create a sequence since DuckDB doesn't support auto-incrementing
CREATE SEQUENCE users_id_seq;
-- Create the table using the sequence
CREATE TABLE users (
  id INTEGER PRIMARY KEY DEFAULT nextval('users_id_seq'),
  name VARCHAR(255) NOT NULL,
  age INTEGER NOT NULL
);
-- Insert some data
INSERT INTO users (name, age) VALUES ('Alice', 25);
INSERT INTO users (name, age) VALUES ('Bob', 30);
INSERT INTO users (name, age) VALUES ('Charlie', 35);
" | duckdb app/connector/my_duckdb/data.duckdb

You can verify this worked by running the following command from the project's root to query all records from the users table:

duckdb app/connector/my_duckdb/data.duckdb "SELECT * FROM users;"

Step 5. Introspect your DuckDB database

Next, use the CLI to introspect your DuckDB database:

ddn connector introspect my_duckdb

After running this, you should see a representation of your database's schema in the app/connector/my_duckdb/config.json file; you can view this using cat or open the file in your editor.

Additionally, you can check which resources are available — and their status — at any point using the CLI:

ddn connector show-resources my_duckdb

Step 6. Add your model

Now, track the table from your DuckDB database as a model in your DDN metadata:

ddn models add my_duckdb "users"

Open the app/metadata directory and you'll find a newly-generated file: Users.hml. The DDN CLI will use this Hasura Metadata Language file to represent the users table from DuckDB in your API as a model.

Step 7. Create a new build

To create a local build, run:

ddn supergraph build local

The build is stored as a set of JSON files in engine/build.

Step 8. Start your local services

Start your local Hasura DDN Engine and DuckDB connector:

ddn run docker-start

Your terminal will be taken over by logs for the different services.

Step 9. Run your first query

In a new terminal tab, open your local console:

ddn console --local

In the GraphiQL explorer of the console, write this query:

query {
  users {
    id
    name
    age
  }
}

You'll get the following response:

{
  "data": {
    "users": [
      {
        "id": 1,
        "name": "Alice",
        "age": 25
      },
      {
        "id": 2,
        "name": "Bob",
        "age": 30
      },
      {
        "id": 3,
        "name": "Charlie",
        "age": 35
      }
    ]
  }
}

Step 10. Iterate on your DuckDB schema

From the root of the project, use the DuckDB CLI to add a new table and insert some data to your DuckDB database:

echo "
-- Create a sequence for posts
CREATE SEQUENCE posts_id_seq;
-- Create the posts table
CREATE TABLE posts (
  id INTEGER PRIMARY KEY DEFAULT nextval('posts_id_seq'),
  user_id INTEGER NOT NULL,
  title VARCHAR(255) NOT NULL,
  content TEXT NOT NULL,
  created_at TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
  FOREIGN KEY (user_id) REFERENCES users(id)
);
-- Insert some seed data
INSERT INTO posts (user_id, title, content) VALUES
  (1, 'My First Post', 'This is Alice''s first post.'),
  (1, 'Another Post', 'Alice writes again!'),
  (2, 'Bob''s Post', 'Bob shares his thoughts.'),
  (3, 'Hello World', 'Charlie joins the conversation.');
" | duckdb app/connector/my_duckdb/data.duckdb

Verify this by running the following command:

echo "
-- Fetch all posts with user information
SELECT
  posts.id AS post_id,
  posts.title,
  posts.content,
  posts.created_at,
  users.name AS author
FROM
  posts
JOIN
  users ON posts.user_id = users.id;
" | duckdb app/connector/my_duckdb/data.duckdb

You should see a list of posts returned with the author's information joined from the users table

Step 11. Refresh your metadata and rebuild your project

tip

The following steps are necessary each time you make changes to your source schema. This includes, adding, modifying, or dropping tables.

Step 11.1. Re-introspect your data source

First, bring down your running services:

CTRL + C

Run the introspection command again:

ddn connector introspect my_duckdb

In app/connector/my_duckdb/config.json, you'll see schema updated to include operations for the posts table. In app/metadata/my_duckdb.hml, you'll see posts present in the metadata as well.

Step 11.2. Update your metadata

Add the posts model:

ddn model add my_duckdb "posts"

Step 11.3. Create a new build

Next, create a new build:

ddn supergraph build local

Step 11.4. Restart your services

Bring down the servies by pressing CTRL+C and start them back up:

ddn run docker-start

Step 12. Query your new build

Head back to your console and query the posts model:

query GetPosts {
  posts {
    id
    title
    content
  }
}

You'll get a response like this:

{
  "data": {
    "posts": [
      {
        "id": 1,
        "title": "My First Post",
        "content": "This is Alice's first post."
      },
      {
        "id": 2,
        "title": "Another Post",
        "content": "Alice writes again!"
      },
      {
        "id": 3,
        "title": "Bob's Post",
        "content": "Bob shares his thoughts."
      },
      {
        "id": 4,
        "title": "Hello World",
        "content": "Charlie joins the conversation."
      }
    ]
  }
}

Step 13. Create a relationship

Find the Posts.hml file in your connector's metadata directory and add the following relationship object to the bottom:

---
kind: Relationship
version: v1
definition:
  name: user
  sourceType: Posts
  target:
    model:
      name: Users
      relationshipType: Object
  mapping:
    - source:
        fieldPath:
          - fieldName: userId
      target:
        modelField:
          - fieldName: id

This will create a relationship that maps the userId for any post to the id of a user, allowing for nested queries.

Step 14. Rebuild your project

As your metadata has changed, create a new build:

ddn supergraph build local

Bring down the servies by pressing CTRL+C and start them back up:

ddn run docker-start

Step 15. Query using your relationship

Now, execute a nested query using your relationship:

query GetPosts {
  posts {
    id
    title
    content
    user {
      id
      name
      age
    }
  }
}

Which should return a result like this:

{
  "data": {
    "posts": [
      {
        "id": 1,
        "title": "My First Post",
        "content": "This is Alice's first post.",
        "user": {
          "id": 1,
          "name": "Alice",
          "age": 25
        }
      },
      {
        "id": 2,
        "title": "Another Post",
        "content": "Alice writes again!",
        "user": {
          "id": 1,
          "name": "Alice",
          "age": 25
        }
      },
      {
        "id": 3,
        "title": "Bob's Post",
        "content": "Bob shares his thoughts.",
        "user": {
          "id": 2,
          "name": "Bob",
          "age": 30
        }
      },
      {
        "id": 4,
        "title": "Hello World",
        "content": "Charlie joins the conversation.",
        "user": {
          "id": 3,
          "name": "Charlie",
          "age": 35
        }
      }
    ]
  }
}

Next steps

Congratulations on completing your first Hasura DDN project with DuckDB! 🎉

Here's what you just accomplished:

• You started with a fresh project and connected it to a local DuckDB database.
• You set up metadata to represent your tables and relationships, which acts as the blueprint for your API.
• Then, you created a build — essentially compiling everything into a ready-to-use API — and successfully ran your first GraphQL queries to fetch data.
• Along the way, you learned how to iterate on your schema and refresh your metadata to reflect changes.

Now, you're equipped to connect and expose your data, empowering you to iterate and scale with confidence. Great work!

Take a look at our DuckDB docs to learn more about how to use Hasura DDN with DuckDB. Or, if you're ready, get started with adding permissions to control access to your API.