Upgrades

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With ClickHouse Cloud you never have to worry about patching and upgrades. We roll out upgrades that include fixes, new features and performance improvements on a periodic basis. For the full list of what is new in ClickHouse refer to our [Cloud changelog](/docs/whats-new/cloud).

Note

We're introducing a new upgrade mechanism, a concept we call "make before break" (or MBB). With this new approach, we add updated replicas before removing the old ones during the upgrade operation. This results in more seamless upgrades that are less disruptive to running workloads.

As part of this change, historical system table data will be retained for up to a maximum of 30 days as part of upgrade events. In addition, any system table data older than December 19, 2024, for services on AWS or GCP, and older than January 14, 2025, for services on Azure won't be retained as part of the migration to the new organization tiers.

## Version compatibility[​](#version-compatibility "Direct link to Version compatibility")

When you create a service, the [`compatibility`](/docs/operations/settings/settings#compatibility) setting is set to the most up-to-date ClickHouse version offered on ClickHouse Cloud at the time your service is initially provisioned.

The `compatibility` setting allows you to use default values of settings from previous versions. When your service is upgraded to a new version, the version specified for the `compatibility` setting doesn't change. This means that default values for settings that existed when you first created your service won't change (unless you have already overridden those default values, in which case they will persist after the upgrade).

You can't manage the service-level default `compatibility` setting for your service. You must [contact support](https://clickhouse.com/support/program) if you would like to change the version set for your service's default `compatibility` setting. However, you can override the `compatibility` setting at the user, role, profile, query, or session level using standard ClickHouse setting mechanisms such as `SET compatibility = '22.3'` in a session or `SETTINGS compatibility = '22.3'` in a query.

## Maintenance mode[​](#maintenance-mode "Direct link to Maintenance mode")

At times, we may need to update your service, which could require disabling certain features such as scaling or idling. In rare cases, we may need to take action on a service that is experiencing issues and bring it back to a healthy state. During such maintenance, you will see a banner on the service page that says *"Maintenance in progress"*. You may still be able to use the service for queries during this time.

You won't be charged for the time that the service is under maintenance. *Maintenance mode* is a rare occurrence and shouldn't be confused with regular service upgrades.

## Release channels (upgrade schedule)[​](#release-channels-upgrade-schedule "Direct link to Release channels (upgrade schedule)")

Users are able to specify the upgrade schedule for their ClickHouse Cloud service by subscribing to a specific release channel. There are three release channels, and the user has the ability to configure the day and time of the week for upgrades with the **scheduled upgrades** feature.

The three release channels are:

- The [**fast release channel**](#fast-release-channel-early-upgrades) for early access to upgrades.
- The [**regular release channel**](#regular-release-channel) is the default, and upgrades on this channel start two weeks after the fast release channel upgrades. If your service on the Scale and Enterprise tier doesn't have a release channel set, it is on the regular release channel by default.
- The [**slow release channel**](#slow-release-channel-deferred-upgrades) is for deferred release. Upgrades on this channel occur two weeks after the regular release channel upgrades.

Note

Basic tier services are automatically enlisted to the fast release channel

### Fast release channel (early upgrades)[​](#fast-release-channel-early-upgrades "Direct link to Fast release channel (early upgrades)")

Scale plan feature

The fast release channel is available in the Scale and Enterprise plans. To upgrade, visit the plans page in the cloud console.

Besides the regular upgrade schedule, we offer a **Fast release** channel if you would like your services to receive updates ahead of the regular release schedule.

Specifically, services will:

- Receive the latest ClickHouse releases
- More frequent upgrades as new releases are tested

You can modify the release schedule of the service in the Cloud console as shown below:

  

This **Fast release** channel is suitable for testing new features in non-critical environments. **It isn't recommended for production workloads with strict uptime and reliability requirements.**

### Regular release channel[​](#regular-release-channel "Direct link to Regular release channel")

For all Scale and Enterprise tier services that don't have a release channel or an upgrade schedule configured, upgrades will be performed as a part of the Regular channel release. This is recommended for production environments.

Upgrades to the regular release channel are typically performed two weeks after the **Fast release channel**.

Note

Basic tier services are upgraded soon after the Fast release channel.

### Slow release channel (deferred upgrades)[​](#slow-release-channel-deferred-upgrades "Direct link to Slow release channel (deferred upgrades)")

Enterprise plan feature

The slow release channel is available in the Enterprise plan. To upgrade, visit the plans page in the cloud console.

We offer a **Slow release** channel if you would like your services to receive upgrades after the regular release schedule.

Specifically, services will:

- Be upgraded after the Fast and Regular release channels roll-outs are complete
- Receive ClickHouse releases ~ 2 weeks after the regular release
- Be meant for customers that want additional time to test ClickHouse releases on their non-production environments before the production upgrade. Non-production environments can either get upgrades on the Fast or the Regular release channel for testing and validation.

Note

You can change release channels at any time. However, in certain cases, the change will only apply to future releases.

- Moving to a faster channel will immediately upgrade your service. i.e. Slow to Regular, Regular to Fast
- Moving to a slower channel won't downgrade your service and keep you on your current version until a newer one is available in that channel. i.e. Regular to Slow, Fast to Regular or Slow

## Scheduled upgrades[​](#scheduled-upgrades "Direct link to Scheduled upgrades")

Enterprise plan feature

Scheduled upgrades are available in the Enterprise plan. To upgrade, visit the plans page in the cloud console.

You can configure an upgrade window for services in the Enterprise tier.

Select the service for which you wish to specify an upgrade scheduled, followed by `Settings` from the left menu. Scroll to `Scheduled upgrades`.

  

Selecting this option will allow you to select the day of the week/time window for database and cloud upgrades.

  

Note

While scheduled upgrades follow the defined schedule, exceptions apply to critical security patches and vulnerability fixes, as well as to scenarios where potential issues could lead to data corruption or data loss. In cases where an urgent security issue is identified, upgrades may be performed outside the scheduled window. Customers will be notified of such exceptions as necessary.

- [Version compatibility](#version-compatibility)- [Maintenance mode](#maintenance-mode)- [Release channels (upgrade schedule)](#release-channels-upgrade-schedule)
      - [Fast release channel (early upgrades)](#fast-release-channel-early-upgrades)- [Regular release channel](#regular-release-channel)- [Slow release channel (deferred upgrades)](#slow-release-channel-deferred-upgrades)- [Scheduled upgrades](#scheduled-upgrades)

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