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Managing data format schemas in Managed Service for ClickHouse®

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Updated at May 13, 2025

Managed Service for ClickHouse® lets you INSERT and SELECT data in different formats. Most of those formats are self-descriptive. This means that they already contain a format schema that describes acceptable data types, their order, and representation in this format. For example, it lets you directly insert data from a file.

Note

Format schema describes the format of data input or output and the data schema describes the structure and layout of the ClickHouse® databases and tables that store this data. These concepts are not interchangeable.

The Cap'n Proto and the Protobuf data formats (including ProtobufSingle) do not contain the format schema, and data is stored in binary format without any structure information. Before you begin processing data in these formats (for example, before inserting data in a table), add a format schema to the Managed Service for ClickHouse® cluster. It will help you correctly interpret the number, order, and type of values when processing binary data.

You can add one or more such format schemas to a Managed Service for ClickHouse® cluster and use them to input and output data in the relevant formats.

Warning

To use the format schemas you added, insert the data into Managed Service for ClickHouse® using the HTTP interface, in this case, data serialization and deserialization is performed on the server side based on the schemas you added.

For more information about data formats, see the ClickHouse® documentation.

You can find examples of working with the Cap'n Proto and Protobuf formats when inserting data into a cluster in the Adding data to a cluster section.

Before connecting the format schema

Managed Service for ClickHouse® only works with readable data format schemas imported to Yandex Object Storage. Before connecting the schema to a cluster:

  1. Prepare a file with a format schema (see the documentation for Cap'n Proto and Protobuf).

  2. To link your service account to a cluster, assign the iam.serviceAccounts.user role or higher to your Yandex Cloud account.

  3. Import the file with the data format schema to Yandex Object Storage.

  4. Connect the service account to the cluster. You will use this service account to configure permissions to access the schema file.

  5. Assign the storage.viewer role to the service account.

  6. In the bucket's ACL, add the READ permission to the service account.

  7. Get a link to the schema file.

Creating a format schema

  1. In the management console, navigate to the folder page and select Managed Service for ClickHouse.
  2. Click the cluster name and open the Data format schemas tab.
  3. Click Create schema.
  4. In the Add schema dialog box, fill out the form by completing the URL field with the previously generated link to the format schema file.
  5. Click Create.

If you do not have the Yandex Cloud (CLI) command line interface yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To create a format schema, run this command:

  • For Cap'n Proto:

    yc managed-clickhouse format-schema create "<format_schema_name>" \
  --cluster-name="<cluster_name>" \
  --type="capnproto" \
  --uri="<link_to_file_in_Object_Storage>"

  • For Protobuf:

    yc managed-clickhouse format-schema create "<format_schema_name>" \
  --cluster-name="<cluster_name>" \
  --type="protobuf" \
  --uri="<link_to_file_in_Object_Storage>"

You can request the cluster name with the list of clusters in the folder.

  1. Open the current Terraform configuration file that defines your infrastructure.

    For more information about creating this file, see Creating clusters.

  2. Add a format_schema block to the Managed Service for ClickHouse® cluster description:

    resource "yandex_mdb_clickhouse_cluster" "<cluster_name>" {
  ...
  format_schema {
    name = "<schema_name>"
    type = "<schema_type>"
    uri  = "<link_to_data_format_schema_file_in_Object_Storage>"
  }
}

    Where type is the schema type, FORMAT_SCHEMA_TYPE_CAPNPROTO or FORMAT_SCHEMA_TYPE_PROTOBUF.

  3. Make sure the settings are correct.

    1. In the command line, navigate to the directory that contains the current Terraform configuration files defining the infrastructure.

    2. Run this command:

      terraform validate

      Terraform will show any errors found in your configuration files.

  4. Confirm updating the resources.

    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.

For more information, see the Terraform provider documentation.

Time limits

A Terraform provider sets the timeout for Managed Service for ClickHouse® cluster operations:

  • Creating a cluster, including by restoring one from a backup: 60 minutes.
  • Editing a cluster: 90 minutes.
  • Deleting a cluster: 30 minutes.

Operations exceeding the set timeout are interrupted.

How do I change these limits?

Add the timeouts block to the cluster description, for example:

resource "yandex_mdb_clickhouse_cluster" "<cluster_name>" {
  ...
  timeouts {
    create = "1h30m" # 1 hour 30 minutes
    update = "2h"    # 2 hours
    delete = "30m"   # 30 minutes
  }
}

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the FormatSchema.Create method and send the following request, e.g., via cURL:

    curl \
    --request POST \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --header "Content-Type: application/json" \
    --url 'https://{{ api-host-mdb }/managed-clickhouse/v1/clusters/<cluster_ID>/formatSchemas' \
    --data '{
              "formatSchemaName": "<schema_name>",
              "type": "<schema_type>",
              "uri": "<file_link>"
            }'

    Where:

    • formatSchemaName: Schema name.
    • type: Schema type, FORMAT_SCHEMA_TYPE_CAPNPROTO or FORMAT_SCHEMA_TYPE_PROTOBUF.
    • uri: Link to the file with the schema in Object Storage.

    You can request the cluster ID with the list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the FormatSchemaService.Create call and and send the following request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/clickhouse/v1/format_schema_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
            "cluster_id": "<cluster_ID>",
            "format_schema_name": "<schema_name>",
            "type": "<schema_type>",
            "uri": "<file_link>"
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.clickhouse.v1.FormatSchemaService.Create

    Where:

    • format_schema_name: Schema name.
    • type: Schema type, FORMAT_SCHEMA_TYPE_CAPNPROTO or FORMAT_SCHEMA_TYPE_PROTOBUF.
    • uri: Link to the file with the schema in Object Storage.

    You can request the cluster ID with the list of clusters in the folder.

  4. View the server response to make sure the request was successful.

Changing a format schema

Managed Service for ClickHouse® does not track changes in the format schema file that is in the Yandex Object Storage bucket.

To update the contents of a schema that is already connected to the cluster:

  1. Upload the file with the current format schema to Yandex Object Storage.
  2. Get a link to this file.
  3. Change the parameters of the format schema that is connected to Managed Service for ClickHouse® by providing a new link to the format schema file.
  1. In the management console, navigate to the folder page and select Managed Service for ClickHouse.
  2. Click the cluster name and open the Data format schemas tab.
  3. Select the appropriate schema, click , and select Edit.

If you do not have the Yandex Cloud (CLI) command line interface yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To change the link to the file in object storage with the format schema, run the command:

yc managed-clickhouse format-schema update "<data_schema_name>" \
  --cluster-name="<cluster_name>" \
  --uri="<new_link_to_file_in_Object_Storage>"

You can request the schema name with a list of format schemas in the cluster and the cluster name with a list of clusters in the folder.

  1. Open the current Terraform configuration file that defines your infrastructure.

    For more information about creating this file, see Creating clusters.

  2. In the Managed Service for ClickHouse® cluster description, change the uri parameter value under format_schema:

    resource "yandex_mdb_clickhouse_cluster" "<cluster_name>" {
  ...
  format_schema {
    name = "<schema_name>"
    type = "<schema_type>"
    uri  = "<new_link_to_schema_file_in_Object_Storage>"
  }
}

  3. Make sure the settings are correct.

    1. In the command line, navigate to the directory that contains the current Terraform configuration files defining the infrastructure.

    2. Run this command:

      terraform validate

      Terraform will show any errors found in your configuration files.

  4. Confirm updating the resources.

    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.

    For more information, see the Terraform provider documentation.

    Time limits

    A Terraform provider sets the timeout for Managed Service for ClickHouse® cluster operations:

    • Creating a cluster, including by restoring one from a backup: 60 minutes.
    • Editing a cluster: 90 minutes.
    • Deleting a cluster: 30 minutes.

    Operations exceeding the set timeout are interrupted.

    How do I change these limits?

    Add the timeouts block to the cluster description, for example:

    resource "yandex_mdb_clickhouse_cluster" "<cluster_name>" {
  ...
  timeouts {
    create = "1h30m" # 1 hour 30 minutes
    update = "2h"    # 2 hours
    delete = "30m"   # 30 minutes
  }
}

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the FormatSchema.Update method and send the following request, e.g., via cURL:

    Warning

    The API method will assign default values to all the parameters of the object you are modifying unless you explicitly provide them in your request. To avoid this, list the settings you want to change in the updateMask parameter as a single comma-separated string.

    curl \
    --request PATCH \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --header "Content-Type: application/json" \
    --url 'https://{{ api-host-mdb }/managed-clickhouse/v1/clusters/<cluster_ID>/formatSchemas/<schema_name>' \
    --data '{
              "updateMask": "uri",
              "uri": "<file_link>"
            }'

    Where:

    • updateMask: List of parameters to update as a single string, separated by commas.

      Here only one parameter is specified: uri.

    • uri: Link to the new file with the schema in Object Storage.

    You can request the cluster ID with the list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the FormatSchemaService.Update call and and send the following request, e.g., via gRPCurl:

    Warning

    The API method will assign default values to all the parameters of the object you are modifying unless you explicitly provide them in your request. To avoid this, list the settings you want to change in the update_mask parameter as an array of paths[] strings.

    Format for listing settings
    "update_mask": {
    "paths": [
        "<setting_1>",
        "<setting_2>",
        ...
        "<setting_N>"
    ]
}

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/clickhouse/v1/format_schema_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
            "cluster_id": "<cluster_ID>",
            "format_schema_name": "<schema_name>",
            "update_mask": {
              "paths": ["uri"]
            },
            "uri": "<file_link>"
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.clickhouse.v1.FormatSchemaService.Create

    Where:

    • format_schema_name: Schema name.

    • update_mask: List of parameters to update as an array of paths[] strings.

      Here only one parameter is specified: uri.

    • uri: Link to the new model file in Object Storage.

    You can request the cluster ID with the list of clusters in the folder.

  4. View the server response to make sure the request was successful.

Disabling a format schema

Note

After disabling a format schema, the corresponding object is kept in the Yandex Object Storage bucket. If you no longer need this format schema object, you can delete it.

  1. In the management console, navigate to the folder page and select Managed Service for ClickHouse.
  2. Click the cluster name and open the Data format schemas tab.
  3. Select the appropriate schema, click , and select Delete.

If you do not have the Yandex Cloud (CLI) command line interface yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To disable a format schema, run the command:

yc managed-clickhouse format-schema delete "<format_schema_name>" \
  --cluster-name="<cluster_name>"

You can request the schema name with a list of format schemas in the cluster and the cluster name with a list of clusters in the folder.

  1. Open the current Terraform configuration file that defines your infrastructure.

    For more information about creating this file, see Creating clusters.

  2. Delete the format_schema description section for the appropriate data format schema from the Managed Service for ClickHouse® cluster description.

  3. Make sure the settings are correct.

    1. In the command line, navigate to the directory that contains the current Terraform configuration files defining the infrastructure.

    2. Run this command:

      terraform validate

      Terraform will show any errors found in your configuration files.

  4. Confirm updating the resources.

    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.

For more information, see the Terraform provider documentation.

Time limits

A Terraform provider sets the timeout for Managed Service for ClickHouse® cluster operations:

  • Creating a cluster, including by restoring one from a backup: 60 minutes.
  • Editing a cluster: 90 minutes.
  • Deleting a cluster: 30 minutes.

Operations exceeding the set timeout are interrupted.

How do I change these limits?

Add the timeouts block to the cluster description, for example:

resource "yandex_mdb_clickhouse_cluster" "<cluster_name>" {
  ...
  timeouts {
    create = "1h30m" # 1 hour 30 minutes
    update = "2h"    # 2 hours
    delete = "30m"   # 30 minutes
  }
}

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the FormatSchema.Delete method and send the following request, e.g., via cURL:

    curl \
    --request DELETE \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --url 'https://mdb.api.cloud.yandex.net/managed-clickhouse/v1/clusters/<cluster_ID>/formatSchemas/<schema_name>'

    You can request the cluster ID with a list of clusters in the folder and the schema name with a list of schemas in the cluster.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the FormatSchemaService.Delete call and and send the following request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/clickhouse/v1/format_schema_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
            "cluster_id": "<cluster_ID>",
            "format_schema_name": "<schema_name>"
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.clickhouse.v1.FormatSchemaService.Delete

    You can request the cluster ID with a list of clusters in the folder and the schema name with a list of schemas in the cluster.

  4. View the server response to make sure the request was successful.

Getting a list of format schemas in a cluster

  1. In the management console, navigate to the folder page and select Managed Service for ClickHouse.
  2. Click the cluster name and open the Data format schemas tab.

If you do not have the Yandex Cloud (CLI) command line interface yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To get a list of format schemas in a cluster, run the command:

yc managed-clickhouse format-schema list --cluster-name="<cluster_name>"

You can request the cluster name with the list of clusters in the folder.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the FormatSchema.List method and send the following request, e.g., via cURL:

    curl \
    --request GET \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --url 'https://mdb.api.cloud.yandex.net/managed-clickhouse/v1/clusters/<cluster_ID>/formatSchemas'

    You can request the cluster ID with the list of clusters in the folder.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the FormatSchemaService.List call and and send the following request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/clickhouse/v1/format_schema_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
            "cluster_id": "<cluster_ID>"
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.clickhouse.v1.FormatSchemaService.List

    You can request the cluster ID with the list of clusters in the folder.

  4. View the server response to make sure the request was successful.

Getting detailed information about a format schema

If you do not have the Yandex Cloud (CLI) command line interface yet, install and initialize it.

The folder specified when creating the CLI profile is used by default. To change the default folder, use the yc config set folder-id <folder_ID> command. You can specify a different folder using the --folder-name or --folder-id parameter.

To get detailed information about a format schema, run the command:

yc managed-clickhouse format-schema get "<format_schema_name>" \
  --cluster-name="<cluster_name>"

You can request the schema name with a list of format schemas in the cluster and the cluster name with a list of clusters in the folder.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Use the FormatSchema.Get method and send the following request, e.g., via cURL:

    curl \
    --request GET \
    --header "Authorization: Bearer $IAM_TOKEN" \
    --url 'https://mdb.api.cloud.yandex.net/managed-clickhouse/v1/clusters/<cluster_ID>/formatSchemas/<schema_name>'

    You can request the cluster ID with a list of clusters in the folder and the schema name with a list of schemas in the cluster.

  3. View the server response to make sure the request was successful.

  1. Get an IAM token for API authentication and put it into the environment variable:

    export IAM_TOKEN="<IAM_token>"

  2. Clone the cloudapi repository:

    cd ~/ && git clone --depth=1 https://github.com/yandex-cloud/cloudapi

    Below, we assume the repository contents are stored in the ~/cloudapi/ directory.

  3. Use the FormatSchemaService.Get call and and send the following request, e.g., via gRPCurl:

    grpcurl \
    -format json \
    -import-path ~/cloudapi/ \
    -import-path ~/cloudapi/third_party/googleapis/ \
    -proto ~/cloudapi/yandex/cloud/mdb/clickhouse/v1/format_schema_service.proto \
    -rpc-header "Authorization: Bearer $IAM_TOKEN" \
    -d '{
            "cluster_id": "<cluster_ID>",
            "format_schema_name": "<schema_name>"
        }' \
    mdb.api.cloud.yandex.net:443 \
    yandex.cloud.mdb.clickhouse.v1.FormatSchemaService.Get

    You can request the cluster ID with a list of clusters in the folder and the schema name with a list of schemas in the cluster.

  4. View the server response to make sure the request was successful.

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