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 allows you to:

• Copy the database without interrupting user service.
• Go without creating an intermediate VM or granting online 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 8443 and 9440 ports in the source endpoint and add the SSL certificate.

To learn more, see Problems addressed by Yandex Data Transfer.

Getting startedGetting started

Allow connecting to the source cluster from the internet.

Required paid resourcesRequired paid resources

The support cost includes:

• Managed Service for ClickHouse® cluster fee: Using computing resources allocated to hosts (including ZooKeeper hosts) and disk space (see Managed Service for ClickHouse® pricing).
• Fee for using public IP addresses if public access is enabled for cluster hosts (see Virtual Private Cloud pricing).
• Transfer fee: 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 your infrastructure:

   Manually

   Using Terraform

   1. Create a security group and configure it.

   2. Create a Managed Service for ClickHouse® target cluster with the computing capacity and storage size appropriate for the environment where the copied database is deployed.

      When creating a cluster, specify the security group prepared earlier.

      The database name in the target cluster must be the same as the source database name.

      If you are going 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 parameters for connecting to the source cluster.

   4. Create a target endpoint:

      • Database type: ClickHouse

      • Endpoint parameters → Connection settings: Managed cluster

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

   5. Create a transfer of the Snapshot type that will use the created endpoints and 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 to connect to a cluster.
      • Managed Service for ClickHouse® target cluster.
      • Source endpoint.
      • Target endpoint.
      • Transfer.

   6. Specify the following in the data-transfer-ch-mch.tf file:

      • Source endpoint parameters:

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

      • Target cluster parameters also used as target endpoint parameters:

        • target_clickhouse_version: ClickHouse® version.
        • target_user and target_password: Name and user password of the database owner.

      • Yandex Cloud CLI parameters to activate the cluster automatically:

        • profile_name: Name of your Yandex Cloud CLI profile.

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

   7. (Optional) If you are going to connect to the cluster via Yandex WebSQL, add the access section to the cluster resource:

      access {
          web_sql = true
      }
      

   8. Make sure the Terraform configuration files are correct using this command:

      terraform validate
      

      If there are any errors in the configuration files, Terraform will point them out.

   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.

      Once created, your transfer will be activated automatically.

Test your transferTest your transfer

1. Wait until the transfer status switches to Completed.

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

   Yandex WebSQL

   CLI

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

   2. Make sure the DB contains the tables from the source cluster. To do this, run this query to the database via the connection you created:

      SHOW TABLES FROM <DB_name>;
      

   3. Make sure the tables contain data from the source cluster tables. To do this, run this query to the table via the connection you created:

      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 using clickhouse-client.

   3. Make sure the DB contains the tables from the source cluster:

      SHOW TABLES FROM <DB_name>;
      

   4. Make sure the tables contain data from the source cluster tables:

      SELECT * FROM <DB_name>.<table_name>;
      

Delete the resources you createdDelete the resources you created

Some resources are not free of charge. To avoid paying for them, delete the resources you no longer need: