# Manage versions in Managed ClickHouse®


Managed ClickHouse® supports multiple ClickHouse versions. You can choose a version when you create a service and upgrade to a newer supported version later.

## Supported ClickHouse versions

Managed ClickHouse supports the following major versions:

- `25.3`: default for services created before May 5, 2026
- `25.8`: default for services created on or after May 5, 2026

List the versions the platform currently offers, along with the default one:

```bash
exo dbaas type show clickhouse
```

If you don't specify a version when you create a service, Exoscale uses the default
version in effect on the creation date. To pick a version explicitly, set the `version`
field in the JSON body passed to `exo x create-dbaas-service-clickhouse`:

```bash
echo '{"plan":"startup-16","version":"25.3","ip-filter":["<your-ip>/32"]}' | \
  exo x create-dbaas-service-clickhouse my-clickhouse -z ch-gva-2
```

> [!NOTE]
> `exo dbaas create` has no ClickHouse type: Managed ClickHouse services are created with
> the `exo x` command above. See
> [Quick Start](/product/dbaas/service-specific/clickhouse/quick-start/) for the full
> creation walkthrough.

Exoscale doesn't automatically upgrade existing `25.3` services to `25.8`. To upgrade the ClickHouse version of an
existing service, see [Upgrade your service](#upgrade-your-service).

For supported versions and end-of-life timelines, see the
[Managed ClickHouse® version support policy](/product/dbaas/service-specific/clickhouse/reference/version-lifecycle/).

## Before you upgrade

Before upgrading your service, complete the following checks:

- Review the upstream ClickHouse release notes.
- Test the upgrade in a development or staging environment by
  forking the service and upgrading the fork
  first.
- Verify that your applications and clients support the target version.
- Ensure recent backups are available.
- Avoid running long-running queries or heavy ingestion during the upgrade.

Downgrading to an earlier ClickHouse version is not supported.

## How upgrades work

During an upgrade, the platform replaces service nodes with new nodes running the
selected version.

- New service nodes are created with the selected ClickHouse version.
- The new nodes start alongside the existing nodes.
- Data is streamed from the existing nodes to the new nodes.
- After the migration completes, the service switches to the upgraded nodes.
- The previous nodes are removed.

This process avoids modifying the existing nodes directly during the upgrade.

During this process:

- Queries connected to nodes being replaced can fail and require retries.
- New connections are routed to upgraded nodes.

## Service availability during upgrades

The service remains available during the upgrade.

- New nodes are added and receive data before old nodes are removed, which helps keep the
  service reachable while the upgrade runs.
- Short interruptions can occur.
- Latency can increase and throughput can decrease during the upgrade.

## Upgrade your service

Upgrade the service to a newer supported ClickHouse version with the
[Exoscale CLI](/reference/cli/exo/).

1. Check the available ClickHouse versions:

   ```bash
   exo dbaas type show clickhouse
   ```

1. Upgrade the service:

   ```bash
   echo '{"version":"CLICKHOUSE_VERSION"}' | \
     exo x update-dbaas-service-clickhouse SERVICE_NAME -z ZONE
   ```

   Parameters:

   - `SERVICE_NAME`: Name of the service
   - `ZONE`: Exoscale zone of the service, for example `ch-gva-2`
   - `CLICKHOUSE_VERSION`: Target ClickHouse version, for example `25.8`

   The service stays reachable during the upgrade.

> [!NOTE]
> Managed ClickHouse® is in early access: dedicated `exo dbaas` subcommands will replace the
> `exo x` commands at general availability.