---
title: Presto
description: Connect Cube to PrestoDB using hostname authentication together with catalog and schema selectors for your query engine layout.
---

## Prerequisites

- The hostname for the [Presto][presto] database server
- The username/password for the [Presto][presto] database server
- The name of the database to use within the [Presto][presto] database server

## Setup

### Manual

Add the following to a `.env` file in your Cube project:

```dotenv
CUBEJS_DB_TYPE=prestodb
CUBEJS_DB_HOST=my.presto.host
CUBEJS_DB_USER=presto_user
CUBEJS_DB_PASS=**********
CUBEJS_DB_PRESTO_CATALOG=my_presto_catalog
CUBEJS_DB_SCHEMA=my_presto_schema
```

## Environment Variables

| Environment Variable       | Description                                                                         | Possible Values                               | Required |
| -------------------------- | ----------------------------------------------------------------------------------- | --------------------------------------------- | :------: |
| [`CUBEJS_DB_HOST`](/reference/configuration/environment-variables#cubejs_db_host)           | The host URL for a database                                                         | A valid database host URL                     |    ✅    |
| [`CUBEJS_DB_PORT`](/reference/configuration/environment-variables#cubejs_db_port)           | The port for the database connection                                                | A valid port number                           |    ❌    |
| [`CUBEJS_DB_USER`](/reference/configuration/environment-variables#cubejs_db_user)           | The username used to connect to the database                                        | A valid database username                     |    ✅    |
| [`CUBEJS_DB_PASS`](/reference/configuration/environment-variables#cubejs_db_pass)           | The password used to connect to the database                                        | A valid database password                     |    ✅    |
| [`CUBEJS_DB_PRESTO_CATALOG`](/reference/configuration/environment-variables#cubejs_db_presto_catalog) | The catalog within Presto to connect to                                             | A valid catalog name within a Presto database |    ✅    |
| [`CUBEJS_DB_PRESTO_AUTH_TOKEN`](/reference/configuration/environment-variables#cubejs_db_presto_auth_token) | The authentication token to use when connecting to Presto/Trino. It will be sent in the `Authorization` header. | A valid authentication token |    ❌    |
| [`CUBEJS_DB_SCHEMA`](/reference/configuration/environment-variables#cubejs_db_schema)         | The schema within the database to connect to                                        | A valid schema name within a Presto database  |    ✅    |
| [`CUBEJS_DB_SSL`](/reference/configuration/environment-variables#cubejs_db_ssl)            | If `true`, enables SSL encryption for database connections from Cube                | `true`, `false`                               |    ❌    |
| [`CUBEJS_DB_MAX_POOL`](/reference/configuration/environment-variables#cubejs_db_max_pool)       | The maximum number of concurrent database connections to pool. Default is `8`       | A valid number                                |    ❌    |
| [`CUBEJS_CONCURRENCY`](/reference/configuration/environment-variables#cubejs_concurrency) | The number of [concurrent queries][ref-data-source-concurrency] to the data source | A valid number |    ❌    |
| [`CUBEJS_DB_EXPORT_BUCKET_TYPE`](/reference/configuration/environment-variables#cubejs_db_export_bucket_type) | The export bucket type for pre-aggregations | `s3`, `gcs` | ❌ |
| [`CUBEJS_DB_EXPORT_BUCKET`](/reference/configuration/environment-variables#cubejs_db_export_bucket) | The export bucket to connect to | A valid bucket URL | ❌ |
| [`CUBEJS_DB_EXPORT_BUCKET_AWS_KEY`](/reference/configuration/environment-variables#cubejs_db_export_bucket_aws_key) | The AWS Access Key ID to use for export bucket writes | A valid AWS Access Key ID | ❌ |
| [`CUBEJS_DB_EXPORT_BUCKET_AWS_SECRET`](/reference/configuration/environment-variables#cubejs_db_export_bucket_aws_secret) | The AWS Secret Access Key to use for export bucket writes | A valid AWS Secret Access Key | ❌ |
| [`CUBEJS_DB_EXPORT_BUCKET_AWS_REGION`](/reference/configuration/environment-variables#cubejs_db_export_bucket_aws_region) | The AWS region to use for export bucket writes | A valid AWS region | ❌ |
| [`CUBEJS_DB_EXPORT_GCS_CREDENTIALS`](/reference/configuration/environment-variables#cubejs_db_export_gcs_credentials) | A Base64 encoded JSON key file for connecting to Google Cloud Storage | A valid Google Cloud JSON key file, encoded as a Base64 string | ❌ |

[ref-data-source-concurrency]: /admin/connect-to-data/concurrency#data-source-concurrency
## Pre-Aggregation Feature Support

### count_distinct_approx

Measures of type
[`count_distinct_approx`][ref-schema-ref-types-formats-countdistinctapprox] can
be used in pre-aggregations when using Presto as a source database. To learn
more about Presto support for approximate aggregate functions, [click
here][presto-docs-approx-agg-fns].

## Pre-Aggregation Build Strategies

<Info>

To learn more about pre-aggregation build strategies, [head
here][ref-caching-using-preaggs-build-strats].

</Info>

| Feature       | Works with read-only mode? | Is default? |
| ------------- | :------------------------: | :---------: |
| Simple        |             ✅             |     ✅      |
| Export Bucket |             ❌             |     ❌      |

By default, Presto uses a [simple][self-preaggs-simple] strategy to
build pre-aggregations.

### Simple

No extra configuration is required to configure simple pre-aggregation builds
for Presto.

### Export Bucket

Presto supports using both [AWS S3][aws-s3] and [Google Cloud Storage][google-cloud-storage] for export bucket functionality.

#### AWS S3

<Info>

Ensure the AWS credentials are correctly configured in IAM to allow reads and
writes to the export bucket in S3.

</Info>

```dotenv
CUBEJS_DB_EXPORT_BUCKET_TYPE=s3
CUBEJS_DB_EXPORT_BUCKET=my.bucket.on.s3
CUBEJS_DB_EXPORT_BUCKET_AWS_KEY=<AWS_KEY>
CUBEJS_DB_EXPORT_BUCKET_AWS_SECRET=<AWS_SECRET>
CUBEJS_DB_EXPORT_BUCKET_AWS_REGION=<AWS_REGION>
```

#### Google Cloud Storage

<Info>

When using an export bucket, remember to assign the **Storage Object Admin**
role to your Google Cloud credentials ([`CUBEJS_DB_EXPORT_GCS_CREDENTIALS`](/reference/configuration/environment-variables#cubejs_db_export_gcs_credentials)).

</Info>

```dotenv
CUBEJS_DB_EXPORT_BUCKET=gs://presto-export-bucket
CUBEJS_DB_EXPORT_BUCKET_TYPE=gcs
CUBEJS_DB_EXPORT_GCS_CREDENTIALS=<BASE64_ENCODED_SERVICE_CREDENTIALS_JSON>
```

## SSL

To enable SSL-encrypted connections between Cube and Presto, set the
[`CUBEJS_DB_SSL`](/reference/configuration/environment-variables#cubejs_db_ssl) environment variable to `true`. For more information on how to
configure custom certificates, please check out [Enable SSL Connections to the
Database][ref-recipe-enable-ssl].

## Custom headers

The Presto driver supports forwarding custom HTTP headers on every request to
the Presto coordinator. This is useful for setting headers like
`X-Presto-Source`, `X-Presto-Client-Tags`, or any other custom header your
Presto coordinator expects.

Custom headers can't be configured via environment variables. Instead, use the
[`driver_factory`](/reference/configuration/config#driver_factory) configuration
option to pass a `headers` object to the driver:

<CodeGroup>

```python title="Python"
from cube import config

@config('driver_factory')
def driver_factory(ctx: dict) -> dict:
  return {
    'type': 'prestodb',
    'headers': {
      'X-Presto-Source': 'cube',
      'X-Presto-Client-Tags': 'user=alice@example.com'
    }
  }
```

```javascript title="JavaScript"
module.exports = {
  driverFactory: ({ dataSource }) => ({
    type: "prestodb",
    headers: {
      "X-Presto-Source": "cube",
      "X-Presto-Client-Tags": "user=alice@example.com"
    }
  })
};
```

</CodeGroup>

In multitenant deployments, you can use the [security
context](/embedding/authentication/security-context) to pass per-tenant headers,
for example to forward a user token from the API request down to Presto:

<CodeGroup>

```python title="Python"
from cube import config

@config('driver_factory')
def driver_factory(ctx: dict) -> dict:
  security_context = ctx['securityContext']
  return {
    'type': 'prestodb',
    'headers': {
      'X-Presto-Client-Tags': f"user={security_context['user_id']}",
      'X-Custom-User-Token': security_context['token']
    }
  }
```

```javascript title="JavaScript"
module.exports = {
  driverFactory: ({ securityContext }) => ({
    type: "prestodb",
    headers: {
      "X-Presto-Client-Tags": `user=${securityContext.user_id}`,
      "X-Custom-User-Token": securityContext.token
    }
  })
};
```

</CodeGroup>

[aws-s3]: https://aws.amazon.com/s3/
[google-cloud-storage]: https://cloud.google.com/storage
[presto]: https://prestodb.io/
[presto-docs-approx-agg-fns]:
  https://prestodb.io/docs/current/functions/aggregate.html
[ref-caching-using-preaggs-build-strats]: /docs/pre-aggregations/using-pre-aggregations#pre-aggregation-build-strategies
[ref-recipe-enable-ssl]: /recipes/configuration/using-ssl-connections-to-data-source
[ref-schema-ref-types-formats-countdistinctapprox]: /reference/data-modeling/measures#type
[self-preaggs-simple]: #simple
