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Loading data from YDB to a ClickHouse® data mart

Written by
Updated at October 24, 2024

With Data Transfer, you can upload data from a Managed Service for YDB database to a Managed Service for ClickHouse® cluster.

To upload data:

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

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

Getting started

Prepare the infrastructure:

  1. Create a Managed Service for YDB database named ydb1 in any suitable configuration.

  2. Create a Managed Service for ClickHouse® cluster in any suitable configuration with publicly available hosts and the following settings:

    • DB name: db1
    • Username: user1

  3. If using security groups in your cluster, make sure they are configured correctly and allow connecting to the 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 required to connect to the Managed Service for ClickHouse® cluster from the internet.
    • 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 parameters:

    • mch_version: ClickHouse® version.
    • mch_password: User password of the ClickHouse® database owner.

  7. 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.

  8. Create the required infrastructure:

    1. Run the command to view planned changes:

      terraform plan

      If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

    2. If you are happy with the planned changes, apply them:

      1. Run the command:

        terraform apply

      2. Confirm the update of 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 the 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 a 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");

Prepare and activate the transfer

  1. Create a source endpoint of the YDB type and specify the DB connection parameters in it:

    • 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: Specify table1.

  2. Create a target endpoint of the ClickHouse® type and specify the cluster connection parameters in it:

    • 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 created endpoints.

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

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

  2. 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.

  3. Create the required infrastructure:

    1. Run the command to view planned changes:

      terraform plan

      If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

    2. If you are happy with the planned changes, apply them:

      1. Run the command:

        terraform apply

      2. Confirm the update of resources.

      3. Wait for the operation to complete.

    Once created, your transfer will be activated automatically.

Test the transfer

Check the transfer performance by testing the copy and replication processes.

Test the copy process

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

  2. Run the following 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 process

  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. Make sure the new data has been added to the target database:

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

    2. Run the following 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 created resources, deactivate the transfer.

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

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

  2. Delete the ydb-to-clickhouse.tf configuration file.

  3. 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.

  4. Confirm updating the resources.

    1. Run the command to view planned changes:

      terraform plan

      If the resource configuration descriptions are correct, the terminal will display a list of the resources to modify and their parameters. This is a test step. No resources are updated.

    2. If you are happy with the planned changes, apply them:

      1. Run the command:

        terraform apply

      2. Confirm the update of resources.

      3. Wait for the operation to complete.

    All the resources described in the ydb-to-clickhouse.tf configuration file will be deleted.

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