@socket.io/postgres-adapter/README.md

The Socket.IO Postgres adapter, allowing to broadcast events between several Socket.IO servers

# Socket.IO Postgres adapter

The `@socket.io/postgres-adapter` package allows broadcasting packets between multiple Socket.IO servers.

<picture>
  <source media="(prefers-color-scheme: dark)" srcset="./assets/adapter_dark.png">
  <img alt="Diagram of Socket.IO packets forwarded through PostgreSQL" src="./assets/adapter.png">
</picture>

**Table of contents**

- [Supported features](#supported-features)
- [Installation](#installation)
- [Usage](#usage)
- [License](#license)

## Supported features

| Feature                         | `socket.io` version | Support                                        |
|---------------------------------|---------------------|------------------------------------------------|
| Socket management               | `4.0.0`             | :white_check_mark: YES (since version `0.1.0`) |
| Inter-server communication      | `4.1.0`             | :white_check_mark: YES (since version `0.1.0`) |
| Broadcast with acknowledgements | `4.5.0`             | :white_check_mark: YES (since version `0.3.0`) |
| Connection state recovery       | `4.6.0`             | :x: NO                                         |

## Installation

```
npm install @socket.io/postgres-adapter
```

## Usage

```js
import { Server } from "socket.io";
import { createAdapter } from "@socket.io/postgres-adapter";
import pg from "pg";

const io = new Server();

const pool = new pg.Pool({
  user: "postgres",
  host: "localhost",
  database: "postgres",
  password: "changeit",
  port: 5432,
});

pool.query(`
  CREATE TABLE IF NOT EXISTS socket_io_attachments (
      id          bigserial UNIQUE,
      created_at  timestamptz DEFAULT NOW(),
      payload     bytea
  );
`);

pool.on("error", (err) => {
  console.error("Postgres error", err);
});

io.adapter(createAdapter(pool));
io.listen(3000);
```

## License

[MIT](LICENSE)