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Scale a ClickHouse cluster

You can scale a ClickHouse cloud database cluster by:

  • changing the number of shards in the cluster — add or remove a shard;

  • scaling node groups — shard and ClickHouse Keeper:

    • select a configuration only with a disk size larger than in the previous configuration;
    • increasing the number of vCPUs, RAM, and disk size in a lineup with custom configurations;
    • choosing a configuration from another lineup, provided that the disk type matches and the disk size is larger.

Add a shard

You can add only one shard at a time. The cluster can contain no more than ten shards.

  1. If the cluster consists of only one shard with one node, add ClickHouse Keeper.

  2. In the Dashboard, on the top menu, click Products and select Managed Databases.

  3. Open the Active tab.

  4. Open the database cluster page → Settings tab.

  5. In the Cluster block, click Add shard.

  6. Optional: change the shard name.

  7. Select a configuration line.

  8. If you selected a lineup with custom configurations, select a disk type and specify the number of vCPUs, RAM size, and disk size.

  9. If you selected a lineup with fixed configurations, select a configuration.

  10. Specify the number of nodes in the shard.

  11. Optional: to make shard nodes accessible from the internet, select the Connect public access checkbox. A separate public IP address will be assigned to each shard node.

    If the cluster subnet does not meet the requirements, public access cannot be enabled. You can prepare a private subnet and assign a public IP address after adding the shard.

  12. Optional: specify the shard weight. Values from 0 to 65535 are available.

  13. Click Save.

Add ClickHouse Keeper

For your information

When adding ClickHouse Keeper, MergeTree tables will be converted to replicated tables (for example, ReplicatedMergeTree). Read more about replicated tables in the Replicated* table engines section of the ClickHouse documentation.

The ClickHouse Keeper node group cannot be removed from the cluster once added.

  1. In the Dashboard, on the top menu, click Products and select Managed Databases.
  2. Open the Active tab.
  3. Open the database cluster page → Settings tab.
  4. In the Cluster block, click Add ClickHouse Keeper.
  5. Optional: change the node group name.
  6. Select a configuration line.
  7. If you selected a lineup with custom configurations, select a disk type and specify the number of vCPUs, RAM size, and disk size.
  8. If you selected a lineup with fixed configurations, select a configuration.
  9. Click Save.

Remove a shard

carefully

Removing a shard will delete all data on that shard.

You can remove a shard from a cluster if it is not the only shard.

  1. In the Dashboard, on the top menu, click Products and select Managed Databases.
  2. Open the Active tab.
  3. Open the cluster page → Settings tab.
  4. In the menu of the shard, select Delete.
  5. Enter the shard name to confirm.
  6. Click Delete.

Scale a node group

Scale a node group when user activity is at its lowest.

  1. In the Dashboard, on the top menu, click Products and select Managed Databases.

  2. Open the Active tab.

  3. Open the database cluster page → Settings tab.

  4. In the menu of the node group, select Change configuration.

  5. Optional: change the node group name.

  6. Scale the node group. You can:

    • select a configuration with a disk size larger than in the previous configuration; ;
    • increase the number of vCPUs, RAM, and disk size in a lineup with custom configurations;
    • choose a configuration from another lineup, provided that the disk type matches and the disk size is larger.

  7. Click Save.