> ## Documentation Index
> Fetch the complete documentation index at: https://cubed3-feat-druid-driver-streaming.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# Druid

> The driver for Druid is community-supported and is not maintained by Cube or the database vendor.

<Warning>
  The driver for Druid is community-supported and is not maintained by Cube or the database vendor.
</Warning>

## Prerequisites

* The URL for the [Druid][druid] database
* The username/password for the [Druid][druid] database server

## Setup

### Manual

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

```dotenv theme={null}
CUBEJS_DB_TYPE=druid
CUBEJS_DB_URL=https://my.druid.host:8082
CUBEJS_DB_USER=druid
CUBEJS_DB_PASS=**********
```

## Environment Variables

| Environment Variable                                                                      | Description                                                                        | Possible Values                | Required |
| ----------------------------------------------------------------------------------------- | ---------------------------------------------------------------------------------- | ------------------------------ | :------: |
| [`CUBEJS_DB_URL`](/reference/configuration/environment-variables#cubejs_db_url)           | The URL for a database                                                             | A valid database URL for Druid |     ✅    |
| [`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_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                 |     ❌    |

[ref-data-source-concurrency]: /admin/connect-to-data/concurrency#data-source-concurrency

## 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? |
| ------------- | :------------------------: | :---------: |
| Batching      |              ✅             |      ✅      |
| Export Bucket |              -             |      -      |

By default, Druid uses [batching][self-preaggs-batching] to build
pre-aggregations.

### Batching

No extra configuration is required to configure batching for Druid.

### Export Bucket

Druid does not support export buckets.

## SSL

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

[druid]: https://druid.apache.org/

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

[self-preaggs-batching]: #batching