# Amazon Athena

## Prerequisites

- [A set of IAM credentials][aws-docs-athena-access] which allow access to [AWS
  Athena][aws-athena]
- [The AWS region][aws-docs-regions]
- [The S3 bucket][aws-s3] on AWS to [store query results][aws-docs-athena-query]

## Setup

### Manual

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

#### Static Credentials

```dotenv
CUBEJS_DB_TYPE=athena
CUBEJS_AWS_KEY=AKIA************
CUBEJS_AWS_SECRET=****************************************
CUBEJS_AWS_REGION=us-east-1
CUBEJS_AWS_S3_OUTPUT_LOCATION=s3://my-athena-output-bucket
CUBEJS_AWS_ATHENA_WORKGROUP=primary
CUBEJS_DB_NAME=my_non_default_athena_database
CUBEJS_AWS_ATHENA_CATALOG=AwsDataCatalog
```

#### IAM Role Assumption

For enhanced security, you can configure Cube to assume an IAM role to access Athena:

```dotenv
CUBEJS_DB_TYPE=athena
CUBEJS_AWS_ATHENA_ASSUME_ROLE_ARN=arn:aws:iam::123456789012:role/AthenaAccessRole
CUBEJS_AWS_REGION=us-east-1
CUBEJS_AWS_S3_OUTPUT_LOCATION=s3://my-athena-output-bucket
CUBEJS_AWS_ATHENA_WORKGROUP=primary
# Optional: if the role requires an external ID
CUBEJS_AWS_ATHENA_ASSUME_ROLE_EXTERNAL_ID=unique-external-id
```

When using role assumption:
- If running in AWS (EC2, ECS, EKS with IRSA), the driver will use the instance's IAM role or service account to assume the target role
- You can also provide <EnvVar>CUBEJS_AWS_KEY</EnvVar> and <EnvVar>CUBEJS_AWS_SECRET</EnvVar> as master credentials for the role assumption

### Cube Cloud

<InfoBox heading="Allowing connections from Cube Cloud IP">

In some cases you'll need to allow connections from your Cube Cloud deployment
IP address to your database. You can copy the IP address from either the
Database Setup step in deployment creation, or from <Btn>Settings →
Configuration</Btn> in your deployment.

</InfoBox>

In Cube Cloud, select AWS Athena** when creating a new deployment and fill in
the required fields:

<Screenshot
  alt="Cube Cloud AWS Athena Configuration Screen"
  src="https://ucarecdn.com/d30fa31d-e6ea-4a73-9950-1786634a1e32/"
/>

Cube Cloud also supports connecting to data sources within private VPCs
if [dedicated infrastructure][ref-dedicated-infra] is used. Check out the
[VPC connectivity guide][ref-cloud-conf-vpc] for details.

[ref-dedicated-infra]: /product/deployment/cloud/infrastructure#dedicated-infrastructure
[ref-cloud-conf-vpc]: /product/deployment/cloud/vpc

## Environment Variables

| Environment Variable                            | Description                                                                                                            | Possible Values                                  | Required |
| ----------------------------------------------- | ---------------------------------------------------------------------------------------------------------------------- | ------------------------------------------------ | :------: |
| <EnvVar>CUBEJS_AWS_KEY</EnvVar>                                | The AWS Access Key ID to use for database connections                                                                  | A valid AWS Access Key ID                        | ❌<sup>1</sup> |
| <EnvVar>CUBEJS_AWS_SECRET</EnvVar>                             | The AWS Secret Access Key to use for database connections                                                              | A valid AWS Secret Access Key                    | ❌<sup>1</sup> |
| <EnvVar>CUBEJS_AWS_REGION</EnvVar>                             | The AWS region of the Cube deployment                                                                                  | [A valid AWS region][aws-docs-regions]           |    ✅    |
| `CUBEJS_AWS_S3_OUTPUT_LOCATION`                 | The S3 path to store query results made by the Cube deployment                                                         | A valid S3 path                                  |    ❌    |
| <EnvVar>CUBEJS_AWS_ATHENA_WORKGROUP</EnvVar>                   | The name of the workgroup in which the query is being started                                                          | [A valid Athena Workgroup][aws-athena-workgroup] |    ❌    |
| <EnvVar>CUBEJS_AWS_ATHENA_CATALOG</EnvVar>                     | The name of the catalog to use by default                                                                              | [A valid Athena Catalog name][awsdatacatalog]    |    ❌    |
| <EnvVar>CUBEJS_AWS_ATHENA_ASSUME_ROLE_ARN</EnvVar>             | The ARN of the IAM role to assume for Athena access                                                                    | A valid IAM role ARN                             |    ❌    |
| <EnvVar>CUBEJS_AWS_ATHENA_ASSUME_ROLE_EXTERNAL_ID</EnvVar>     | The external ID to use when assuming the IAM role (if required by the role's trust policy)                             | A string                                          |    ❌    |
| <EnvVar>CUBEJS_DB_NAME</EnvVar>                                | The name of the database to use by default                                                                             | A valid Athena Database name                     |    ❌    |
| <EnvVar>CUBEJS_DB_SCHEMA</EnvVar>                              | The name of the schema to use as `information_schema` filter. Reduces count of tables loaded during schema generation. | A valid schema name                              |    ❌    |
| <EnvVar>CUBEJS_CONCURRENCY</EnvVar>                            | The number of [concurrent queries][ref-data-source-concurrency] to the data source                                     | A valid number                                   |    ❌    |

<sup>1</sup> Either provide <EnvVar>CUBEJS_AWS_KEY</EnvVar> and <EnvVar>CUBEJS_AWS_SECRET</EnvVar> for static credentials, or use <EnvVar>CUBEJS_AWS_ATHENA_ASSUME_ROLE_ARN</EnvVar> for role-based authentication. When using role assumption without static credentials, the driver will use the AWS SDK's default credential chain (IAM instance profile, EKS IRSA, etc.).

[ref-data-source-concurrency]: /product/configuration/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 AWS Athena as a source database. To learn
more about AWS Athena's support for approximate aggregate functions, [click
here][aws-athena-docs-approx-agg-fns].

## Pre-Aggregation Build Strategies

<InfoBox>

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

</InfoBox>

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

By default, AWS Athena uses a [batching][self-preaggs-batching] strategy to
build pre-aggregations.

### Batching

No extra configuration is required to configure batching for AWS Athena.

### Export Bucket

<WarningBox>

AWS Athena **only** supports using AWS S3 for export buckets.

</WarningBox>

#### AWS S3

For [improved pre-aggregation performance with large
datasets][ref-caching-large-preaggs], enable export bucket functionality by
configuring Cube with the following environment variables:

<InfoBox>

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

</InfoBox>

```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>
```

## SSL

Cube does not require any additional configuration to enable SSL as AWS Athena
connections are made over HTTPS.

[aws-athena]: https://aws.amazon.com/athena
[aws-athena-workgroup]:
  https://docs.aws.amazon.com/athena/latest/ug/workgroups-benefits.html
[awsdatacatalog]:
  https://docs.aws.amazon.com/athena/latest/ug/understanding-tables-databases-and-the-data-catalog.html
[aws-s3]: https://aws.amazon.com/s3/
[aws-docs-athena-access]:
  https://docs.aws.amazon.com/athena/latest/ug/security-iam-athena.html
[aws-docs-athena-query]:
  https://docs.aws.amazon.com/athena/latest/ug/querying.html
[aws-docs-regions]:
  https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-regions-availability-zones.html#concepts-available-regions
[aws-athena-docs-approx-agg-fns]:
  https://prestodb.io/docs/current/functions/aggregate.html#approximate-aggregate-functions
[ref-caching-large-preaggs]:
  /product/caching/using-pre-aggregations#export-bucket
[ref-caching-using-preaggs-build-strats]:
  /product/caching/using-pre-aggregations#pre-aggregation-build-strategies
[ref-schema-ref-types-formats-countdistinctapprox]: /product/data-modeling/reference/types-and-formats#count_distinct_approx
[self-preaggs-batching]: #batching
