# Databases (/services/databases)



Unbind creates and runs databases for you. Open the command panel, pick **Database** and choose one:

| Database   | Versions                      | Default |
| ---------- | ----------------------------- | ------- |
| PostgreSQL | 14, 15, 16, 17, 18            | 18      |
| MySQL      | 8.0, 8.4                      | 8.4     |
| Redis      | 8.4, 8.6, 8.8, 8.10           | 8.10    |
| MongoDB    | 7.0, 8.0, 8.2, 8.3            | 8.3     |
| ClickHouse | 24.12, 25.5, 26.3, 26.5, 26.7 | 26.3    |

Pick the version and the storage size, then press **Deploy**. Storage starts at 1 GB. You can grow it later, but not shrink it.

## Connect a service to it [#connect-a-service-to-it]

A database publishes its connection details as variables that other services can reference. You never copy a password by hand.

On the service that needs the database, add a variable, type `$` in the value and pick the database's URL from the list:

```bash
DATABASE_URL=${Postgres.UNBIND_DATABASE_URL_PRIVATE}
```

Use the private URL. It works only from inside your Unbind instance and never leaves it. See [Variables](/services/variables) for how references work.

The username, password and default database name are managed by Unbind. They show up on the database service as protected variables, and they cannot be edited or deleted.

## Reach it from outside [#reach-it-from-outside]

Databases are private by default. To connect from your laptop or an outside tool, open the database's settings and set **Network Access** to **Public**. The database then also gets a public address and a public URL variable.

<Callout type="warn" title="Public means public">
  Anyone on the internet can try to connect. Only the password protects the data. Switch back to
  **Private** when you are done.
</Callout>

## Backups [#backups]

Backups go to an S3 compatible bucket. First [add a bucket](/teams/s3-storage) to the team. Then, in the database's settings under **Backups**:

* **Backup Bucket**: where backups are stored.
* **Backup Schedule**: every hour, every 6 or 12 hours, daily, weekly, or a custom cron expression like `0 3 * * *`.
* **Backup Retention**: how many backups to keep. Older ones are deleted.

Backups are available for PostgreSQL, MySQL, MongoDB and ClickHouse. Redis has none.

<Callout title="Restoring">
  There is no restore button in the UI yet. The backups are standard files in your bucket, written
  by the backup tools of each database. Test a restore before you need one.
</Callout>

## PostgreSQL replication settings [#postgresql-replication-settings]

PostgreSQL has a **Database** section in its settings with **WAL Level**. Leave it on `replica` unless a tool asks for logical replication, such as change data capture. With `logical` you can also set **Replication Slots**, **WAL Senders** and **Slot WAL keep size**.