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Managing shards MongoDB

Written by
Updated at October 28, 2024

You can create a sharded cluster or enable sharding later. After that, you can add and configure shards.

Make sure your shards consist of at least three MONGOD hosts for higher availability. We do not recommend sharding small collections: query processing is faster with a standard replica cluster.

Alert

After cluster sharding is enabled:

  • There is no way to disable sharding. The cluster will always maintain a minimum number of MONGOS, MONGOCFG, or MONGOINFRA hosts depending on the sharding type.
  • To access databases, use only the MONGOS or MONGOINFRA hosts that route queries to shards. For this purpose, edit host addresses in your application code accordingly.

Enabling sharding

The Managed Service for MongoDB interface lets you quickly create a MongoDB sharding infrastructure.

To learn how to directly shard your MongoDB database and collections, see Sharding collections.

To enable sharding, you need:

  • At least 3 MONGOINFRA hosts for standard sharding.
  • At least 2 MONGOS and 3 MONGOCFG hosts for advanced sharding.

Note

Sharding is not supported for hosts of b1.medium and b2.medium classes. If you do not see the Shards tab, upgrade the cluster host class to the supported value.

  1. Go to the folder page and select Managed Service for MongoDB.

  2. Click the cluster name and open the Shards tab.

  3. Click Enable.

  4. Select a sharding type:

    • Standard: Based on MONGOINFRA hosts.

    • Advanced: Based on MONGOS and MONGOCFG hosts.

      For more information, see Sharding.

    Warning

    After you enable sharding, you can't change its type.

  5. Set the parameters of the hosts that will provide access to the sharded data.

  6. Click Enable sharding.

The cluster will start updating, with the requested hosts and first shard of the cluster created.

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 enable standard cluster sharding using MONGOINFRA hosts, run this command (the list of supported parameters in the example is not exhaustive):

    yc managed-mongodb cluster enable-sharding \
  --cluster-name=<cluster_name> \
  --host type=mongoinfra,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --host type=mongoinfra,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --host type=mongoinfra,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --mongoinfra resource-preset=<host_class>,`
    `disk-size=<storage_size_in_GB>,`
    `disk-type=<disk_type>

    Where:

  • To enable advanced cluster sharding using MONGOS and MONGOCFG hosts, run this command (the list of supported parameters in the example is not exhaustive):

    yc managed-mongodb cluster enable-sharding \
  --cluster-name=<cluster_name> \
  --host type=mongos,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --host type=mongos,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --mongos resource-preset=<host_class>,`
    `disk-size=<storage_size_in_GB>,`
    `disk-type=<disk_type> \
  --host type=mongocfg,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --host type=mongocfg,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --host type=mongocfg,`
    `zone-id=<availability_zone>,`
    `subnet-name=<subnet_name> \
  --mongocfg resource-preset=<host_class>,`
    `disk-size=<storage_size_in_GB>,`
    `disk-type=<disk_type>

    Where:

  1. Make sure the provider version you are using is 0.90 or higher:

    terraform version

    Result example:

    Terraform v1.4.6
on darwin_arm64
+ provider registry.terraform.io/yandex-cloud/yandex v0.91.0
    If the version is older

    Update the provider version:

    1. In the folder with the .tf configuration file, add the credentials to environment variables.

    2. In the same folder, initialize the provider with the updated version specified in the configuration file:

      terraform init -upgrade

    3. Check the provider version:

      terraform version

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

    For information on how to create this file, see Creating a cluster.

  3. Add additional resources to the configuration file.

    For standard sharding of the cluster using MONGOINFRA hosts
    resources_mongoinfra {
  resource_preset_id = "<host_class>"
  disk_type_id       = "<disk_type>"
  disk_size          = <storage_size_in_GB>
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongoinfra"
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongoinfra"
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongoinfra"
}
    For advanced sharding of the cluster using MONGOS and MONGOCFG hosts
    resources_mongos {
  resource_preset_id = "<host_class>"
  disk_type_id       = "<disk_type>"
  disk_size          = <storage_size_in_GB>
}

resources_mongocfg {
  resource_preset_id = "<host_class>"
  disk_type_id       = "<disk_type>"
  disk_size          = <storage_size_in_GB>
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongos"
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongos"
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongocfg"
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongocfg"
}

host {
  zone_id   = "<availability_zone>"
  subnet_id = "<subnet_ID>"
  type      = "mongocfg"
}

  4. 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.

  5. 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.

To enable cluster sharding, use the enableSharding REST API method for the Cluster resource or the ClusterService/EnableSharding gRPC API call and provide the cluster ID in the clusterId request parameter.

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

Listing shards in a cluster

  1. Go to the folder page and select Managed Service for MongoDB.
  2. Click the cluster name and open the Shards tab.

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 get a list of shards in a cluster, run the following command:

yc managed-mongodb shards list --cluster-name <cluster_name>

Result:

+------+
| NAME |
+------+
| rs01 |
| rs02 |
+------+

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

To get a list of cluster shards, use the listShards REST API method for the Cluster resource or the ClusterService/ListShards gRPC API call and provide the cluster ID in the clusterId request parameter.

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

Creating a shard

The number of shards in Managed Service for MongoDB clusters is limited by the CPU and RAM quotas available to DB clusters in your cloud. To check the resources currently in use, open the Quotas page and find Yandex Managed Service for MongoDB.

  1. Go to the folder page and select Managed Service for MongoDB.
  2. Click the cluster name and open the Shards tab.
  3. Click Create shard.
  4. Enter a name for the shard and add the number of hosts you need.
  5. Click Create shard.

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 create a shard, run the command below (not all the supported parameters are listed):

yc managed-mongodb shards add <new_shard_name> \
  --cluster-name=<cluster_name> \
  --host zone-id=<availability_zone>,`
    `subnet-name=<subnet_name>

Where:

  1. Make sure the provider version you are using is 0.90 or higher:

    terraform version

    Result example:

    Terraform v1.4.6
on darwin_arm64
+ provider registry.terraform.io/yandex-cloud/yandex v0.91.0
    If the version is older

    Update the provider version:

    1. In the folder with the .tf configuration file, add the credentials to environment variables.

    2. In the same folder, initialize the provider with the updated version specified in the configuration file:

      terraform init -upgrade

    3. Check the provider version:

      terraform version

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

    For information on how to create this file, see Creating a cluster.

  3. Add to the Managed Service for MongoDB cluster description the required number of host blocks with MONGOD in the type parameter and shard name in the shard_name parameter:

    resource "yandex_mdb_mongodb_cluster" "<cluster_name>" {
  ...
  host {
    zone_id    = "<availability_zone>"
    subnet_id  = "<subnet_ID>"
    type       = "mongod"
    shard_name = "<shard_name>"
  }
}

  4. 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.

  5. 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.

To create a shard, use the addShard REST API method for the Cluster resource or the ClusterService/AddShard gRPC API call and provide the following in the request:

  • Cluster ID in the clusterId parameter.
  • Shard name in the shardName parameter.
  • Shard host configuration in the array of hostSpecs parameters.

You can get the shard name with a list of cluster shards and the cluster ID with a list of clusters in the folder.

Deleting a shard

You can delete a shard from a MongoDB cluster if it is not the only shard there. To replace the only shard in a cluster, first create a new shard and then remove the old one.

Note

The removeShard operation will be called for the shard being deleted and will safely transfer data to the remaining shards.

  1. Go to the folder page and select Managed Service for MongoDB.
  2. Click the cluster name and open the Shards tab.
  3. Click the icon in the shard row and select Delete.
  4. In the window that opens, click Remove.

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 delete a shard from the cluster, run:

yc managed-mongodb shards delete <shard_name> \
  --cluster-name=<cluster_name>

You can request the shard name with a list of cluster shards and the cluster name with a list of clusters in a folder.

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

    For information on how to create this file, see Creating a cluster.

  2. Delete all shard-related host sections from the Managed Service for MongoDB cluster description.

  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. Type yes and press Enter.

    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.

To delete a shard, use the deleteShard REST API method for the Cluster resource or the ClusterService/DeleteShard gRPC API call and provide the following in the request:

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