Automatic scaling | ClickHouse Docs

Scaling is the ability to adjust available resources to meet client demands. Scale and Enterprise tier services can be scaled horizontally by calling an API programmatically or changing settings in the UI. Scale tier services and Enterprise tier services with standard 1:4 profiles can also be autoscaled vertically to meet application demands.

Scale plan feature

Automatic vertical scaling is available in the Scale and Enterprise plans. To upgrade, visit the plans page in the cloud console.

How scaling works in ClickHouse Cloud

ClickHouse Cloud supports manual horizontal scaling for Scale and Enterprise tier services. Scale tier services also support vertical autoscaling; Enterprise tier vertical autoscaling support depends on the profile, as described below. Horizontal autoscaling is available in Private Preview for Scale and Enterprise tier services.

For Enterprise tier services scaling works as follows:

Horizontal scaling: Manual horizontal scaling is available across all standard and custom profiles on the Enterprise tier.
Vertical scaling:
- Standard 1:4 profiles support vertical autoscaling.
- Custom profiles (highMemory and highCPU) don’t support vertical autoscaling or manual vertical scaling. However, these services can be scaled vertically by contacting support.

Note

Scaling in ClickHouse Cloud happens in what we call a “Make Before Break” (MBB) approach. This adds one or more replicas of the new size before removing the old replicas, preventing any loss of capacity during scaling operations. By eliminating the gap between removing existing replicas and adding new ones, MBB creates a more seamless and less disruptive scaling process. It is especially beneficial in scale-up scenarios, where high resource utilization triggers the need for additional capacity, since removing replicas prematurely would only exacerbate the resource constraints. As part of this approach, we wait up to an hour to let any existing queries complete on the older replicas before removing them. This balances the need for existing queries to complete, while at the same time ensuring that older replicas don’t linger around for too long.

Learn more

Vertical autoscaling — Automatic CPU and memory scaling based on usage
Horizontal autoscaling — Automatic replica scaling based on workload demand
Horizontal scaling — Manual replica scaling via API or UI
Make Before Break (MBB) — How ClickHouse Cloud performs seamless scaling operations
Automatic idling — Cost savings through automatic service suspension
Scaling recommendations — Understanding scaling recommendations
Scheduled scaling — Understanding the Scheduled Scaling feature, which lets you define exactly when your service should scale up or down, independent of real-time metrics
Large single-replica services — Vertical scaling for single-replica services on the Scale and Enterprise tiers