> ## 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.

# RisingWave

> Point Cube at RisingWave using the Postgres-compatible driver and your cluster host, database, and credential settings.

[RisingWave](https://risingwave.com) is a distributed streaming database that enables
processing and management of real-time data with a Postgres-style SQL syntax. It is
available as an [open-source edition](https://github.com/risingwavelabs/risingwave)
and a managed cloud service.

## Prerequisites

* [Credentials](https://docs.risingwave.com/docs/current/risingwave-docker-compose/#connect-to-risingwave) for the RisingWave cluster

## Setup

RisingWave provides a Postgres-compatible interface. You can connect Cube to RisingWave
as if it's a regular [Postgres][ref-postgres] data source.

### Manual

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

```dotenv theme={"dark"}
CUBEJS_DB_TYPE=postgres
CUBEJS_DB_HOST=risingwave_host
CUBEJS_DB_PORT=risingwave_port
CUBEJS_DB_NAME=risingwave_database
CUBEJS_DB_USER=risingwave_user
CUBEJS_DB_PASS=risingwave_password
```

## 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_NAME`](/reference/configuration/environment-variables#cubejs_db_name)         | The name of the database to connect to                                                                                                            | A valid database name     |     ✅    |
| [`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_SSL`](/reference/configuration/environment-variables#cubejs_db_ssl)           | If `true`, enables [SSL encryption](https://docs.risingwave.com/docs/current/secure-connections-with-ssl-tls/) 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            |     ❌    |

[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
not be used in pre-aggregations when using RisingWave as a source database.

## 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        |              ✅             |      ✅      |
| Batching      |              -             |      -      |
| Export bucket |              -             |      -      |

By default, RisingWave uses a simple strategy to build pre-aggregations.

### Simple

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

### Batching

RisingWave does not support batching.

### Export bucket

RisingWave does not support export buckets.

[ref-postgres]: /admin/connect-to-data/data-sources/postgres

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

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