> This page location: Postgres > Connect to Postgres > Connection methods > Neon serverless driver > Configuration
> Full Neon documentation index: https://neon.com/docs/llms.txt

> Summary: Configuration reference for the Neon serverless driver (`@neondatabase/serverless`): `arrayMode`, `fullResults`, and `fetchOptions` for the HTTP `neon()` function; individual and function-valued connection parameters (1.2.0+); `transaction()` options (`isolationLevel`, `readOnly`, `deferrable`); setting JWT claims for Row-Level Security in a transaction; and `neonConfig` options for `Pool` and `Client`. For installation and basic usage, see the Neon serverless driver page.

# Neon serverless driver configuration

Result formats, fetch options, connection parameters, and transaction options for the Neon serverless driver

This page covers configuration options for the Neon serverless driver. The driver works with its defaults, so all of these options are optional. For installation, a quick start, and basic HTTP and WebSocket usage, see [Neon serverless driver](https://neon.com/docs/serverless/serverless-driver).

## Query result and fetch options

The examples in this section assume a query function created with `neon()`:

```javascript
import { neon } from '@neondatabase/serverless';
const sql = neon(process.env.DATABASE_URL);
const postId = 12;
```

By default, the query function returns only the rows resulting from the provided SQL query, and it returns them as an array of objects where the keys are column names. For example:

```javascript
const rows = await sql`SELECT * FROM posts WHERE id = ${postId}`;
// -> [{ id: 12, title: "My post", ... }]
```

You can customize the return format using the configuration options `fullResults` and `arrayMode`. These options are available both on the `neon(...)` function and on the query function it returns.

- `arrayMode: boolean`, `false` by default

  The default `arrayMode` value is `false`. When it is true, rows are returned as an array of arrays instead of an array of objects:

  ```javascript
  const sql = neon(process.env.DATABASE_URL, { arrayMode: true });
  const rows = await sql`SELECT * FROM posts WHERE id = ${postId}`;
  // -> [[12, "My post", ...]]
  ```

  Or, with the same effect when using query():

  ```javascript
  const sql = neon(process.env.DATABASE_URL);
  const rows = await sql.query('SELECT * FROM posts WHERE id = $1', [postId], { arrayMode: true });
  // -> [[12, "My post", ...]]
  ```

- `fullResults: boolean`

  The default `fullResults` value is `false`. When it is `true`, additional metadata is returned alongside the result rows, which are then found in the `rows` property of the return value. The metadata matches what would be returned by `node-postgres`:

  ```javascript
  const sql = neon(process.env.DATABASE_URL, { fullResults: true });
  const results = await sql`SELECT * FROM posts WHERE id = ${postId}`;
  /* -> {
    rows: [{ id: 12, title: "My post", ... }],
    fields: [
      { name: "id", dataTypeID: 23, ... },
      { name: "title", dataTypeID: 25, ... },
      ...
    ],
    rowCount: 1,
    rowAsArray: false,
    command: "SELECT"
  }
  */
  ```

  Or, with the same effect when using query():

  ```javascript
  const sql = neon(process.env.DATABASE_URL);
  const results = await sql.query('SELECT * FROM posts WHERE id = $1', [postId], {
    fullResults: true,
  });
  // -> { ... same as above ... }
  ```

- `fetchOptions: Record<string, any>`

  The `fetchOptions` option can also be passed to either `neon(...)` or the `query` function. This option takes an object that is merged with the options to the `fetch` call.

  For example, to increase the priority of every database `fetch` request:

  ```javascript
  import { neon } from '@neondatabase/serverless';
  const sql = neon(process.env.DATABASE_URL, { fetchOptions: { priority: 'high' } });
  const rows = await sql`SELECT * FROM posts WHERE id = ${postId}`;
  ```

  Or to implement a `fetch` timeout:

  ```javascript
  import { neon } from '@neondatabase/serverless';
  const sql = neon(process.env.DATABASE_URL);
  const abortController = new AbortController();
  const timeout = setTimeout(() => abortController.abort('timed out'), 10000);
  const rows = await sql.query('SELECT * FROM posts WHERE id = $1', [postId], {
    fetchOptions: { signal: abortController.signal },
  }); // throws an error if no result received within 10s
  clearTimeout(timeout);
  ```

For additional details, see [Options and configuration](https://github.com/neondatabase/serverless/blob/main/CONFIG.md#options-and-configuration).

## Connection parameters

The usual way to configure the connection is a full connection string:

```javascript
const sql = neon(process.env.DATABASE_URL);
```

You can also pass individual connection parameters in the options object. The supported parameters are `user` (or `username`), `password`, `host` (or `hostname`), `port`, `database`, and `connectionString`. They can supplement a connection string, override parts of it, or fully replace it:

```javascript
// No connection string: pass the parts individually
const sql = neon({ user, password, host, database });

// Override part of a connection string
const sql = neon(process.env.DATABASE_URL, { host: readReplicaHost });
```

Each parameter can be a string (or a number, for `port`), or a **sync or async function that's resolved on every query**. Resolving on every query is useful for short-lived credentials that must be fetched fresh, such as an OIDC token used as the password:

```javascript
const sql = neon(DATABASE_URL_WITHOUT_PASSWORD, {
  password: async () => await getAccessToken(),
});
```

The same connection parameters are accepted by the `query` and `transaction` functions.

The `Client` and `Pool` classes also accept a sync or async `password` function. To combine one with a connection string, use the exported `parseIntoClientConfig` helper:

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

const pool = new Pool({
  ...parseIntoClientConfig(process.env.DATABASE_URL),
  password: async () => await getAccessToken(),
});
```

**Note:** Connection parameters, password functions with `pipelineConnect` enabled (the default), and `parseIntoClientConfig` require `@neondatabase/serverless` 1.2.0 or later.

## Transaction options

For how to run queries with `transaction()`, see [Issue multiple queries with the transaction() function](https://neon.com/docs/serverless/serverless-driver#issue-multiple-queries-with-the-transaction-function).

The optional second argument to `transaction()`, `options`, has the same keys as the options to the ordinary query function (`arrayMode`, `fullResults` and `fetchOptions`) plus three additional keys that concern the transaction configuration. These transaction-related keys are: `isolationLevel`, `readOnly` and `deferrable`.

Pass query and transaction options as the second argument of `transaction()`, not on the individual queries inside it. The TypeScript types don't accept options on individual queries, and `fetchOptions` can't apply per query because the whole transaction is sent as a single `fetch` request. For example:

```javascript
const [rows] = await sql.transaction([sql`SELECT now()`], { arrayMode: true });
```

- `isolationLevel`

  This option selects a Postgres [transaction isolation mode](https://www.postgresql.org/docs/current/transaction-iso.html). If present, it must be one of `ReadUncommitted`, `ReadCommitted`, `RepeatableRead`, or `Serializable`.

- `readOnly`

  If `true`, this option ensures that a `READ ONLY` transaction is used to execute the queries passed. This is a boolean option. The default value is `false`.

- `deferrable`

  If `true` (and if `readOnly` is also `true`, and `isolationLevel` is `Serializable`), this option ensures that a `DEFERRABLE` transaction is used to execute the queries passed. This is a boolean option. The default value is `false`.

For additional details, see [transaction(...) function](https://github.com/neondatabase/serverless/blob/main/CONFIG.md#transaction-function).

## Using transactions with JWT self-verification

When using Row-Level Security (RLS) to secure backend SQL with the Neon serverless driver, you may need to set JWT claims within a transaction context. Use this for custom JWT verification flows in backend APIs, where you want to ensure user-specific access to rows according to RLS policies.

Here's an example of how to use the `transaction()` function with self-verified JWT claims:

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

// Example JWT verification function, typically in a separate auth utilitiy file (implement according to your auth provider)
async function verifyJWT(jwtToken, jwksURL) {
  // Your JWT verification logic here
  // This should return the decoded payload
  return { payload: { sub: 'user123', email: 'user@example.com' } };
}

const sql = neon(process.env.DATABASE_URL);

// Get JWT token from request headers or context
const jwtToken = req.headers.authorization?.replace('Bearer ', '');
const jwksURL = process.env.JWKS_URL; // Your JWKS endpoint

// Verify the JWT and extract claims
const { payload } = await verifyJWT(jwtToken, jwksURL);
const claims = JSON.stringify(payload);

// Use transaction to set JWT claims and query data
const [, my_table] = await sql.transaction([
  sql`SELECT set_config('request.jwt.claims', ${claims}, true)`,
  sql`SELECT * FROM my_table`,
]);
```

**Important:** When using JWT self-verification with RLS, ensure your database connection string uses a role that does **not** have the `BYPASSRLS` attribute. Avoid using the `neondb_owner` role in your connection string, as it bypasses Row-Level Security policies.

This pattern allows you to:

- Verify JWTs using your own authentication logic
- Set the JWT claims in the database session context
- Access JWT claims in your RLS policies
- Execute multiple queries within a single transaction while maintaining the auth context

## neonConfig options

The `neonConfig` object configures `Pool` and `Client` connections over WebSockets, for example to supply a WebSocket constructor on Node.js 21 and earlier, or to change pipelining and proxy settings. For the full list, see [neonConfig configuration](https://github.com/neondatabase/serverless/blob/main/CONFIG.md#neonconfig-configuration) in the driver repository.

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