Vertical Autoscaling
Vertical auto scaling
Automatic vertical scaling is available in the Scale and Enterprise plans. To upgrade, visit the plans page in the cloud console.
Scale and Enterprise services support autoscaling based on CPU and memory usage. We constantly monitor the historical usage of a service over a lookback window (spanning the past 30 hours) to make scaling decisions. If the usage rises above or falls below certain thresholds, we scale the service appropriately to match the demand.
For non-MBB services, CPU-based autoscaling kicks in when CPU usage crosses an upper threshold in the range of 50-75% (actual threshold depends on the size of the cluster). At this point, CPU allocation to the cluster is doubled. If CPU usage falls below half of the upper threshold (for instance, to 25% in case of a 50% upper threshold), CPU allocation is halved.
For services already utilizing the MBB scaling approach, scaling up happens at a CPU threshold of 75%, and scale down happens at half of that threshold, or 37.5%.
Memory-based auto-scaling scales the cluster to 125% of the maximum memory usage, or up to 150% if OOM (out of memory) errors are encountered.
The larger of the CPU or memory recommendation is picked, and CPU and memory allocated to the service are scaled in lockstep increments of 1 CPU and 4 GiB memory.
Configuring vertical auto scaling
The scaling of ClickHouse Cloud Scale or Enterprise services can be adjusted by organization members with the Admin role. To configure vertical autoscaling, go to the Settings tab for your service and adjust the minimum and maximum memory, along with CPU settings as shown below.
Single replica services can't be scaled for all tiers.
Set the Maximum memory for your replicas at a higher value than the Minimum memory. The service will then scale as needed within those bounds. These settings are also available during the initial service creation flow. Each replica in your service will be allocated the same memory and CPU resources.
You can also choose to set these values the same, essentially "pinning" the service to a specific configuration. Doing so will immediately force scaling to the desired size you picked.
It's important to note that this will disable any auto scaling on the cluster, and your service won't be protected against increases in CPU or memory usage beyond these settings.
For Enterprise tier services, standard 1:4 profiles will support vertical autoscaling. Custom profiles won't support vertical autoscaling or manual vertical scaling at launch. However, these services can be scaled vertically by contacting support.
