Migrating ClickHouse® clusters

With Data Transfer, you can transfer your database from a third-party ClickHouse® source cluster to a Managed Service for ClickHouse® target cluster.

This method enables you to:

• Copy the database without interrupting user service.
• Eliminate the need for an intermediate VM or public internet access to your Managed Service for ClickHouse® target cluster.

You can also use this method to transfer data between two Managed Service for ClickHouse® clusters. For a successful transfer, specify the listening ports 8443 and 9440 on the source endpoint and add an SSL certificate.

For more information, see Problems addressed by Yandex Data Transfer.

Getting startedGetting started

Enable inbound internet connections to the source cluster.

Required paid resourcesRequired paid resources

• Managed Service for ClickHouse® cluster: use of computing resources allocated to hosts, storage and backup size (see Managed Service for ClickHouse® pricing).
• Public IP addresses if public access is enabled for cluster hosts (see Virtual Private Cloud pricing).
• Each transfer: use of computing resources and the number of transferred data rows (see Data Transfer pricing).

Transferring dataTransferring data

1. Prepare the source cluster.

2. Set up the infrastructure:

   Manually

   Using Terraform

   1. Create a security group and configure it.

   2. Create a Managed Service for ClickHouse® target cluster whose computing and storage capacity match those of the source database environment.

      When creating a cluster, specify the security group you created earlier.

      The source and target database names must be the same.

      To connect to the cluster via Yandex WebSQL, enable WebSQL access in the cluster settings.

   3. Create a source endpoint:

      • Database type: ClickHouse.

      • Endpoint parameters → Connection settings: On-premise.

        Specify the source cluster connection settings.

   4. Create a target endpoint:

      • Database type: ClickHouse.

      • Endpoint parameters → Connection settings: Managed cluster.

        Select your target cluster from the list and specify its connection settings.

   5. Create a Snapshot-type transfer, configure it to use the previously created endpoints, then activate it.

   1. If you do not have Terraform yet, install it.

   2. Get the authentication credentials. You can add them to environment variables or specify them later in the provider configuration file.

   3. Configure and initialize a provider. There is no need to create a provider configuration file manually, you can download it.

   4. Place the configuration file in a separate working directory and specify the parameter values. If you did not add the authentication credentials to environment variables, specify them in the configuration file.

   5. Download the data-transfer-ch-mch.tf configuration file to the same working directory.

      This file describes:

      • Network.
      • Subnet.
      • Security group and the rule required for connecting to a cluster.
      • Managed Service for ClickHouse® target cluster.
      • Source endpoint.
      • Target endpoint.
      • Transfer.

   6. In the data-transfer-ch-mch.tf file, specify the following:

      • Source endpoint parameters:

        • source_user and source_pwd: Username and password to access the source database.
        • source_db_name: Database name.
        • source_host: ClickHouse® server IP address or FQDN.
        • source_shard: Shard name.
        • source_http_port and source_native_port: HTTP and ClickHouse® native interface ports.

      • Target cluster parameters used as target endpoint parameters:

        • target_clickhouse_version: ClickHouse® version.
        • target_user and target_password: Database owner username and password.

      • Yandex Cloud CLI parameters for automating cluster activation:

        • profile_name: Yandex Cloud CLI profile name.

          If you do not have the Yandex Cloud CLI yet, install and initialize it.

   7. Optionally, to enable connections via Yandex WebSQL, add the access section to the cluster resource:

      access {
          web_sql = true
      }
      

   8. Validate your Terraform configuration files using this command:

      terraform validate
      

      Terraform will display any configuration errors detected in your files.

   9. Create the required infrastructure:

      1. Run this command to view the planned changes:

         terraform plan
         

         If you described the configuration correctly, the terminal will display a list of the resources to update and their parameters. This is a verification step that does not apply changes to your resources.

      2. If everything looks correct, apply the changes:

         1. Run this command:

            terraform apply
            

         2. Confirm updating the resources.

         3. Wait for the operation to complete.

      All the required resources will be created in the specified folder. You can check resource availability and their settings in the management console.

      The transfer will be activated automatically upon creation.

Test the transferTest the transfer

1. Wait for the transfer status to change to Completed.

2. Make sure the data from the ClickHouse® source cluster has been transferred to the Managed Service for ClickHouse® database:

   Yandex WebSQL

   CLI

   1. Create a connection to the database in the Managed Service for ClickHouse® cluster.

   2. Check that the database contains all tables from the source cluster by running the following query via the connection you created:

      SHOW TABLES FROM <DB_name>;
      

   3. Check that the tables contain the same data as the source cluster tables by running the following query against them:

      SELECT * FROM <DB_name>.<table_name>;
      

   1. Get an SSL certificate to connect to the Managed Service for ClickHouse® cluster.

   2. Connect to the database in the Managed Service for ClickHouse® cluster via clickhouse-client.

   3. Check that the database contains all tables from the source cluster:

      SHOW TABLES FROM <DB_name>;
      

   4. Check that the tables contain the same data as the source cluster tables:

      SELECT * FROM <DB_name>.<table_name>;
      

Delete the resources you createdDelete the resources you created

To minimize resource consumption, delete the resources you no longer need: