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Changing ClickHouse® settings at the server level

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Updated at November 18, 2024

You can specify ClickHouse® settings at the server level to configure the way the databases or individual tables work in a Managed Service for ClickHouse® cluster. You can specify settings in several ways:

Specifying ClickHouse® settings using the Yandex Cloud interfaces

Changing some server settings will restart ClickHouse® servers on the cluster hosts.

Note

You cannot directly update the Max server memory usage value. Managed Service for ClickHouse® sets this value automatically depending on the amount of RAM available to ClickHouse® hosts. To edit this setting, you first need to change the ClickHouse® host class. For more information, see Memory management.

To configure ClickHouse®:

  1. In the management console, go to the folder page and select Managed Service for ClickHouse.
  2. Select the cluster and click Edit in the top panel.
  3. Under DBMS settings, click Settings.
  4. Specify the ClickHouse® settings.
  5. Click Save changes.

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

The folder specified in the CLI profile is used by default. You can specify a different folder using the --folder-name or --folder-id parameter.

To configure ClickHouse®:

  1. View the full list of settings specified for the cluster:

    yc managed-clickhouse cluster get <cluster_name_or_ID> --full

  2. View a description of the update cluster configuration CLI command:

    yc managed-clickhouse cluster update-config --help

  3. Set the required parameter values:

    yc managed-clickhouse cluster update-config <cluster_name_or_ID> \
   --set <parameter_1_name>=<value_1>,...

To configure ClickHouse®:

  1. Open the current Terraform configuration file with an infrastructure plan.

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

  2. In the Managed Service for ClickHouse® cluster description, under clickhouse.config, change the values of the following parameters:

    resource "yandex_mdb_clickhouse_cluster" "<cluster_name>" {
  ...
  clickhouse {
    ...

    config {
      # General DBMS settings
      ...

      merge_tree {
        # MergeTree engine settings
        ...
      }

      kafka {
        # General settings to get data from Apache Kafka
        ...
      }

      kafka_topic {
        # Settings for an individual Apache Kafka topic
        ...
      }

      rabbit_mq {
        # Settings for getting data from RabbitMQ
        username = "<username>"
        password = "<password>"
      }

      compression {
        # Data compression settings
        method              = "<compression_method>"
        min_part_size       = <data_part_size>
        min_part_size_ratio = <size_ratio>
      }

      graphite_rollup {
        # GraphiteMergeTree engine settings for thinning, aggregating, and averaging (rollup) Graphite data.
        ...
      }
    }
    ...
  }
  ...
}

    Where:

    • method: Compression method, LZ4 or ZSTD.
    • min_part_size: Minimum size of a table data part, bytes.
    • min_part_size_ratio: Smallest table data part to the full table size ratio.

  3. Make sure the settings are correct.

    1. Using the command line, navigate to the folder that contains the up-to-date Terraform configuration files with an infrastructure plan.

    2. Run the command:

      terraform validate

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

  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.

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
  }
}

To configure ClickHouse®, use the update REST API method for the Cluster resource or the ClusterService/Update gRPC API call and provide the following in the request:

  • Cluster ID in the clusterId parameter. To find out the cluster ID, get a list of clusters in the folder.
  • Required values in the configSpec.clickhouse.config parameter.
  • List of settings to update in the updateMask parameter.

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.

Checking MergeTree table settings

  1. Connect to the database in the cluster.

  2. To view all table-level settings, run the following query:

    SHOW CREATE TABLE <table_name>;

    Warning

    The SHOW CREATE TABLE output only includes settings overridden by the user. If a user-defined value matches the default value, this setting is also displayed in the output.

Specifying settings for MergeTree tables using SQL queries

Changing settings when creating a MergeTree table

  1. Connect to the database in the cluster.

  2. Create a table. To specify its settings, list them in the SETTINGS parameter, separated by commas:

    CREATE TABLE <table_name>
   (
   <table_column_description>
   )
   ENGINE = MergeTree
   PRIMARY KEY (<column_or_group_of_columns>)
   SETTINGS
   <setting_name> = <setting_value>,
   <setting_name> = <setting_value>;

    Example query for the merge_with_ttl_timeout and merge_with_recompression_ttl_timeout settings:

    CREATE TABLE <table_name>
   (
   user_id UInt32,
   message String,
   )
   ENGINE = MergeTree
   PRIMARY KEY (user_id)
   SETTINGS merge_with_ttl_timeout = 15000,
   merge_with_recompression_ttl_timeout = 15000;

For more information about creating MergeTree tables, see the ClickHouse® documentation.

Changing the settings of an existing MergeTree table

  1. Connect to the database in the cluster.

  2. To change the settings for an existing table, run the following query:

    ALTER TABLE <table_name> MODIFY SETTING <setting_name> = <new_setting_value>;

    You can change multiple settings in a single query. To do this, list the <setting_name> = <new_setting_value> pairs separated by commas.

Restoring the default settings of a MergeTree table

  1. Connect to the database in the cluster.

  2. To restore a default setting value of an existing table, run the following query:

    ALTER TABLE <table_name> RESET SETTING <setting_name>;

    You can restore multiple default settings in a single query. To do this, list the names of the settings separated by commas.

ClickHouse® is a registered trademark of ClickHouse, Inc.

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