> ## Documentation Index
> Fetch the complete documentation index at: https://docs.cube.dev/llms.txt
> Use this file to discover all available pages before exploring further.

# Trino

> Map Cube to Trino with host credentials plus catalog, schema, SSL, and optional bearer-token variables on the shared Presto driver.

## Prerequisites

* The hostname for the [Trino][trino] database server
* The username/password for the [Trino][trino] database server
* The name of the database to use within the [Trino][trino] database server

## Setup

### Manual

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

```dotenv theme={"dark"}
CUBEJS_DB_TYPE=trino
CUBEJS_DB_HOST=my.trino.host
CUBEJS_DB_USER=trino_user
CUBEJS_DB_PASS=**********
CUBEJS_DB_PRESTO_CATALOG=my_trino_catalog
CUBEJS_DB_SCHEMA=my_trino_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 Trino as a source database. To learn more
about Trino support for approximate aggregate functions, [click
here][trino-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, Trino uses a [simple][self-preaggs-simple] strategy to
build pre-aggregations.

### Simple

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

### Export Bucket

Trino 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 theme={"dark"}
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 theme={"dark"}
CUBEJS_DB_EXPORT_BUCKET=gs://trino-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 Trino, 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 Trino driver supports forwarding custom HTTP headers (e.g., `X-Trino-Source`,
`X-Trino-Routing-Group`, `X-Trino-Client-Tags`, or any other custom header) on
every request to the Trino coordinator. See the [Trino client
protocol][trino-docs-client-protocol] for the list of headers accepted by Trino.

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" theme={"dark"}
  from cube import config

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

  ```javascript title="JavaScript" theme={"dark"}
  module.exports = {
    driverFactory: ({ dataSource }) => ({
      type: "trino",
      headers: {
        "X-Trino-Source": "cube",
        "X-Trino-Routing-Group": "etl",
        "X-Trino-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 Trino:

<CodeGroup>
  ```python title="Python" theme={"dark"}
  from cube import config

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

  ```javascript title="JavaScript" theme={"dark"}
  module.exports = {
    driverFactory: ({ securityContext }) => ({
      type: "trino",
      headers: {
        "X-Trino-Client-Tags": `user=${securityContext.user_id}`,
        "X-Custom-User-Token": securityContext.token
      }
    })
  };
  ```
</CodeGroup>

[trino-docs-client-protocol]: https://trino.io/docs/current/develop/client-protocol.html

[aws-s3]: https://aws.amazon.com/s3/

[google-cloud-storage]: https://cloud.google.com/storage

[ref-caching-using-preaggs-build-strats]: /docs/pre-aggregations/using-pre-aggregations#pre-aggregation-build-strategies

[self-preaggs-simple]: #simple

[trino]: https://trino.io/

[trino-docs-approx-agg-fns]: https://trino.io/docs/current/functions/aggregate.html#approximate-aggregate-functions

[ref-recipe-enable-ssl]: /recipes/configuration/using-ssl-connections-to-data-source

[ref-schema-ref-types-formats-countdistinctapprox]: /reference/data-modeling/measures#type