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Loading data from YDB to Yandex Managed Service for ClickHouse® using Yandex Data Transfer

Written by
Updated at January 22, 2026

Data Transfer enables you to transfer data from a Managed Service for YDB database to a Managed Service for ClickHouse® cluster.

To transfer data:

  1. Prepare the test data.
  2. Set up and activate the transfer.
  3. Test your transfer.

If you no longer need the resources you created, delete them.

  • Managed Service for YDB database (see Managed Service for YDB pricing). Its pricing is based on deployment mode:

    • In serverless mode, you pay for data operations and storage volume, including stored backups.
    • In dedicated instance mode, you pay for the use of computing resources allocated to the database, storage size, and backups.

  • Managed Service for ClickHouse® cluster: 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).

Getting started

Set up the infrastructure:

  1. Create a Managed Service for YDB database named ydb1 with your preferred configuration.

  2. Create a Managed Service for ClickHouse® cluster with publicly accessible hosts and the following settings:

    • DB name: db1.
    • Username: user1.

  3. If using security groups, make sure they are configured correctly and allow inbound connections to your Managed Service for ClickHouse® cluster.

  4. Create a service account named ydb-account with the ydb.editor role. The transfer will use it to access the database.

  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 ydb-to-clickhouse.tf configuration file to the same working directory.

    This file describes:

    • Network.
    • Subnet.
    • Security group and rules for internet access to the Managed Service for ClickHouse® cluster.
    • Managed Service for YDB database.
    • Managed Service for ClickHouse® target cluster.
    • Source endpoint.
    • Target endpoint.
    • Transfer.

  6. In the ydb-to-clickhouse.tf file, specify the following settings:

    • mch_version: ClickHouse® version.
    • mch_password: ClickHouse® database owner’s password.

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

    terraform validate

    Terraform will show any errors found in your configuration files.

  8. 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.

Prepare your test data

  1. Connect to the Managed Service for YDB database.

  2. Create a row-oriented table named table1 with the following columns:

    Name Type Primary key
    Id Int64 Yes
    Name Utf8

    You can create this table using the following SQL query:

    CREATE TABLE table1 (
    Id Int64,
    Name Utf8,
    PRIMARY KEY (Id)
)

  3. Populate the table with data using the following SQL query:

    INSERT INTO table1 (Id, Name)
VALUES
    (1, "Anna"),
    (2, "Robert"),
    (3, "Umar"),
    (4, "Algul"),
    (5, "Viktor");

Set up and activate the transfer

  1. Create a YDB-type source endpoint with the following database connection settings:

    • Connection settings:

      • Database: Select the Managed Service for YDB database from the list.

      • Service account ID: Select the ydb-account service account.

    • Included paths list: table1.

  2. Create a ClickHouse®-type target endpoint with the following cluster connection settings:

    • Connection type: Managed cluster.
    • Managed cluster: <ClickHouse®_target_cluster_name> from the drop-down list.
    • Database: db1.
    • User: user1.
    • Password: <user_password>.

  3. Create a transfer of the Snapshot and replication-type that will use the endpoints you created.

  4. Activate the transfer and wait for its status to change to Replicating.

  1. In the ydb-to-clickhouse.tf file, set transfer_enabled to 1.

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

    terraform validate

    Terraform will show any errors found in your configuration files.

  3. 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.

    Once created, your transfer will be activated automatically.

Test your transfer

To make sure the transfer works correctly, test the copy and replication operations.

Test the copy operation

  1. Connect to the db1 database in the Managed Service for ClickHouse® target cluster.

  2. Run this query:

    SELECT * FROM db1.table1;
    Response example
    # | Id  | Name     | __data_transfer_commit_time | __data_transfer_delete_time
--+-----+----------+-----------------------------+----------------------------
1 | "1" | "Anna"   | "1722023098109014844"       | "0"
2 | "2" | "Robert" | "1722023098109014844"       | "0"
3 | "3" | "Umar"   | "1722023098109014844"       | "0"
4 | "4" | "Algul"  | "1722023098109014844"       | "0"
5 | "5" | "Viktor" | "1722023098109014844"       | "0"

Test the replication operation

  1. Connect to the Managed Service for YDB database.

  2. Add data to the table named table1:

    INSERT INTO table1 (Id, Name)
VALUES
    (6, "Maria"),
    (7, "Alex");

  3. Check that the data has been replicated to the target database:

    1. Connect to the db1 database in the Managed Service for ClickHouse® target cluster.

    2. Run this query:

      SELECT * FROM db1.table1;
      Response example
      # | Id  | Name     | __data_transfer_commit_time | __data_transfer_delete_time
--+-----+----------+-----------------------------+----------------------------
1 | "1" | "Anna"   | "1722023098109014844"       | "0"
2 | "2" | "Robert" | "1722023098109014844"       | "0"
3 | "3" | "Umar"   | "1722023098109014844"       | "0"
4 | "4" | "Algul"  | "1722023098109014844"       | "0"
5 | "5" | "Viktor" | "1722023098109014844"       | "0"
6 | "6" | "Maria"  | "1722023655224000000"       | "0"
7 | "7" | "Alex"   | "1722023655225000000"       | "0"

Delete the resources you created

Note

Before deleting the resources, deactivate the transfer.

Some resources are not free of charge. Delete the resources you no longer need to avoid paying for them:

  1. In the terminal window, go to the directory containing the infrastructure plan.

    Warning

    Make sure the directory has no Terraform manifests with the resources you want to keep. Terraform deletes all resources that were created using the manifests in the current directory.

  2. Delete resources:

    1. Run this command:

      terraform destroy

    2. Confirm deleting the resources and wait for the operation to complete.

    All the resources described in the Terraform manifests will be deleted.

ClickHouse® is a registered trademark of ClickHouse, Inc.

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