@neondatabase/serverless [BETA]

@neondatabase/serverless is Neon's PostgreSQL driver for JavaScript and TypeScript. It's:

* Low-latency, thanks to message pipelining and other optimizations
* Ideal for serverless/edge deployment, using https and WebSockets in place of TCP
* A drop-in replacement for node-postgres, aka pg (on which it's based)

Get started

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Install it with your preferred JavaScript package manager. For example:

``bash
npm install @neondatabase/serverless
`

Using TypeScript? No worries: types are included.

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Get your connection string from the Neon console and set it as an environment variable. Something like:

`
DATABASE_URL=postgres://username:password@host.neon.tech/neondb
`

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For one-shot queries, use the neon function. For instance:

`javascript
import { neon } from '@neondatabase/serverless';
const sql = neon(process.env.DATABASE_URL);

const [post] = await sqlSELECT * FROM posts WHERE id = ${postId};
// post is now { id: 12, title: 'My post', ... } (or undefined)
`

Note: interpolating ${postId} here is safe from SQL injection.

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Turn this example into a complete API endpoint deployed on Vercel Edge Functions at https://myapp.vercel.dev/api/post?postId=123 by following two simple steps:

1. Create a new file api/post.ts:

`javascript
import { neon } from '@neondatabase/serverless';
const sql = neon(process.env.DATABASE_URL);

export default async (req: Request, ctx: any) => {
// get and validate the postId query parameter
const postId = parseInt(new URL(req.url).searchParams.get('postId'), 10);
if (isNaN(postId)) return new Response('Bad request', { status: 400 });

// query and validate the post
const [post] = await sqlSELECT * FROM posts WHERE id = ${postId};
if (!post) return new Response('Not found', { status: 404 });

// return the post as JSON
return new Response(JSON.stringify(post), {
headers: { 'content-type': 'application/json' }
});
}

export const config = {
runtime: 'edge',
regions: ['iad1'], // specify the region nearest your Neon DB
};
`

2. Test and deploy

`bash
npm install -g vercel # install vercel CLI
npx vercel env add DATABASE_URL # paste Neon connection string, select all environments
npx vercel dev # check working locally, then ...
npx vercel deploy
`

The neon query function has a few additional options.

Sessions, transactions, and node-postgres compatibility

A query using the neon function, as shown above, is carried by an https fetch request.

This should work — and work fast — from any modern JavaScript environment. But you can only send one query at a time this way: sessions and transactions are not supported.

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Multiple queries can be issued via fetch request within a single, non-interactive transaction by using the transaction() function. This is exposed as a property on the query function.

For example:

`javascript
import { neon } from '@neondatabase/serverless';
const sql = neon(process.env.DATABASE_URL);
const showLatestN = 10;

const [posts, tags] = await sql.transaction([
sqlSELECT * FROM posts ORDER BY posted_at DESC LIMIT ${showLatestN},
sqlSELECT * FROM tags,
]);
`

There are some additional options when using transaction().

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Use the Pool or Client constructors, instead of the functions described above, when you need:

* session or interactive transaction support, and/or

* compatibility with node-postgres, which supports query libraries like Kysely or Zapatos.

Queries using Pool and Client are carried by WebSockets. There are two key things to know about this:

1. In Node.js and some other environments, there's no built-in WebSocket support. In these cases, supply a WebSocket constructor function.

2. In serverless environments such as Vercel Edge Functions or Cloudflare Workers, WebSocket connections can't outlive a single request.

That means Pool or Client objects must be connected, used and closed within a single request handler. Don't create them outside a request handler; don't create them in one handler and try to reuse them in another; and to avoid exhausting available connections, don't forget to close them.

These points are demonstrated in the examples below.

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* The full API guide to Pool and Client can be found in the node-postgres docs.

* There are a few additional configuration options that apply to Pool and Client here.

Example: Node.js with Pool.connect()

In Node.js, it takes two lines to configure WebSocket support. For example:

`javascript
import { Pool, neonConfig } from '@neondatabase/serverless';

import ws from 'ws';
neonConfig.webSocketConstructor = ws; // <-- this is the key bit

const pool = new Pool({ connectionString: process.env.DATABASE_URL });
pool.on('error', err => console.error(err)); // deal with e.g. re-connect
// ...

const client = await pool.connect();

try {
await client.query('BEGIN');
const { rows: [{ id: postId }] } = await client.query('INSERT INTO posts (title) VALUES ($1) RETURNING id', ['Welcome']);
await client.query('INSERT INTO photos (post_id, url) VALUES ($1, $2)', [postId, 's3.bucket/photo/url']);
await client.query('COMMIT');

} catch (err) {
await client.query('ROLLBACK');
throw err;

} finally {
client.release();
}

// ...
await pool.end();
`

Other WebSocket libraries are available. For example, you could replace ws in the above example with undici:

`typescript
import { WebSocket } from 'undici';
neonConfig.webSocketConstructor = WebSocket;
`

Example: Vercel Edge Function with Pool.query()

We can rewrite the Vercel Edge Function shown above (under the heading 'Deploy it') to use Pool, as follows:

`javascript
import { Pool } from '@neondatabase/serverless';

// don't create a Pool or Client here, outside the request handler

export default async (req: Request, ctx: any) => {
// create a Pool inside the request handler
const pool = new Pool({ connectionString: process.env.DATABASE_URL });

// get and validate the postId query parameter
const postId = parseInt(new URL(req.url).searchParams.get('postId'), 10);
if (isNaN(postId)) return new Response('Bad request', { status: 400 });

// query and validate the post
const [post] = await pool.query('SELECT * FROM posts WHERE id = $1', [postId]);
if (!post) return new Response('Not found', { status: 404 });

// end the Pool inside the same request handler
// (unlike await, ctx.waitUntil won't hold up the response)
ctx.waitUntil(pool.end());

// return the post as JSON
return new Response(JSON.stringify(post), {
headers: { 'content-type': 'application/json' }
});
}

export const config = {
runtime: 'edge',
regions: ['iad1'], // specify the region nearest your Neon DB
};
`

Note: we don't actually use the pooling capabilities of Pool in this example. But it's slightly briefer than using Client and, because Pool.query is designed for one-shot queries, we may in future automatically route these queries over https for lower latency.

Example: Vercel Edge Function with Client

Using Client instead, the example looks like this:

`javascript
import { Client } from '@neondatabase/serverless';

// don't create a Pool or Client here, outside the request handler

export default async (req: Request, ctx: any) => {
// create a Client inside the request handler
const client = new Client(process.env.DATABASE_URL);
await client.connect();

// get and validate the postId query parameter
const postId = parseInt(new URL(req.url).searchParams.get('postId'), 10);
if (isNaN(postId)) return new Response('Bad request', { status: 400 });

// query and validate the post
const [post] = await client.query('SELECT * FROM posts WHERE id = $1', [postId]);
if (!post) return new Response('Not found', { status: 404 });

// end the Client inside the same request handler
// (unlike await, ctx.waitUntil won't hold up the response)
ctx.waitUntil(client.end());

// return the post as JSON
return new Response(JSON.stringify(post), {
headers: { 'content-type': 'application/json' }
});
}

export const config = {
runtime: 'edge',
regions: ['iad1'], // specify the region nearest your Neon DB
};
`

More examples

These repos show how to use @neondatabase/serverless` with a variety of environments and tools:

* Raw SQL + Vercel Edge Functions
* Raw SQL via https + Vercel Edge Functions
* Raw SQL + Cloudflare Workers
* Kysely + Vercel Edge Functions
* Zapatos + Vercel Edge Functions

Bring your own Postgres database

This package comes configured to connect to a Neon database. But you can also use it to connect to your own Postgres instances if you run your own WebSocket proxy.

Open-source

This code is released under the MIT license.

Feedback and support

Please visit Neon Community or Support.