Configuring Cluster Resources

Configuring the resources your ClickHouse® cluster will use

You may need to change the size and structure of your ClickHouse® cluster at some point. (There are slightly different options for rescaling a swarm cluster; those are discussed below.)

Rescaling a standard ClickHouse cluster

Clicking the Cluster Resources menu item displays this dialog:

Cluster Rescale

Figure 1 - The Rescale Compute dialog for a standard cluster

The current properties of your cluster are shown when you open the dialog. You can change the node type for your cluster, the number of shards, and the number of replicas. You can only specify availability zones if you create new replicas. In Figure 1, we increased the number of replicas from 2 to 4; otherwise the Availability Zones checkboxes would be disabled.

At the bottom of the dialog is an estimate of the monthly cost of your rescaled cluster, including the difference between your current configuration and the new one. Click OK to rescale the cluster with the new values. As you would expect, the rescaling time varies with the size of the cluster, as each node is rescaled individually.

The rescaling operation takes place one node at a time, so the impact of rescaling should have a minimal impact on the performance of your applications. (Assuming your cluster has more than one replica, of course.)

NOTE: Rescaling a cluster resets its activity schedule to ALWAYS ON. If your cluster is using the RESCALE ON SCHEDULE activity schedule, you’ll see this confirmation message:

Rescale Confirmation dialog

Figure 2 - The Rescale Confirmation dialog

(You’ll see similar messages for STOP WHEN INACTIVE or STOP ON SCHEDULE.) If you rescale the cluster, you’ll need to recreate its activity schedule. See Configuring Activity Schedules for all the details.

Rescaling a swarm cluster

If you’re rescaling a swarm cluster, you can only change the node type and the number of nodes:

Figure 3 - Rescaling a swarm cluster

At the bottom of the dialog is an estimate of the monthly cost of your rescaled swarm cluster, including the difference between your current configuration and the new one. Click OK to rescale the swarm cluster with the new values.