Tenant Resource Limitation

Currently, the resource isolation of CnosDB is tenant-level. There are two types of restrictions: one is to limit the objects created by tenants; One is to limit the size and number of times tenants can read and write data.Both types of restrictions can be set using the same SQL, and this SQL can only be used by the superuser.

Syntax

alter tenant <tenant_name> set _limiter '<limiter_json>';

Parameter Description

• tenant_name: The name of the tenant to be set.
• limiter_json: The content of tenant resource limit, specifically classified as: object limit object_config and read and write limit request_config, content format must be json format.

object_config, object limit, the parameters included are as follows:

Parameter name	Description	Required	Units
max_users_number	Specifies the maximum number of users (members) to be a tenant; when set to null, it is unbounded.	Yes	Count
max_databases	Specifies the maximum number of databases for each tenant; when set to null, it is unlimited.	Yes	Count
max_shard_number	Specifies the maximum number of shards that can be created in a tenant's database; when set to null, this is unlimited.	Yes	Count
max_replica_number	Specifies the maximum number of replicas that can be created for the database under the tenant; when set to null, this is unlimited.	Yes	Count
max_retention_time	Specifies the maximum TTL parameter of the database under the tenant. When null, it is unlimited.	Yes	Day

Example:

"object_config": {
  "max_users_number": 1,
  "max_databases": 3,
  "max_shard_number": 2,
  "max_replicate_number": 2,
  "max_retention_time": 30
},

request_config, read and write limit, the parameters included are as follows:

Parameter name	Description	Required	Units
data_in	Limit the size of write requests over a period of time; when set to null, it is unbounded.	Yes	Byte
data_out	Limit the size of read requests over a period of time; when set to null, it is unbounded.	Yes	Byte
queries	Limit the number of read requests in a time.Set to null indicates no limit.	Yes	Count
writes	Limit the number of write requests in a time.When set to null, it is unlimited.	Yes	Count

The data_in and data_out limits are implemented by the token bucket algorithm and consist of two parts: One is a remote token bucket on meta, specified by remote_bucket, and the other is a local token bucket on data, specified by local_bucket, where tokens are measured in bytes.

Parameters of remote_bucket are as follows:

Parameter name	Description	Units
max	Limit the maximum number of tokens in a bucket	Count
initial	Limit the number of tokens in the initial bucket	Count
refill	Limit the number of tokens populated at a time	Count
interval	Time interval to fill the token	ms

Parameters of local_bucket are as follows:

Parameters	Description	Units
max	Limit the maximum number of tokens in a bucket	Count
initial	Limit the number of tokens in the initial bucket	Count

The following example bucket setup allows 10KB of data to be written every 100ms and 10KB of data to be cased every 100ms;

Example data writing settings

"data_in": {
  "remote_bucket": {
    "max": 10000,
    "initial": 0,
    "refill": 10000,
    "interval": 100
  },
  "local_bucket": {
    "max": 10000,
    "initial": 0
  }
  },
  "data_out": {
  "remote_bucket": {
    "max": 10000,
    "initial": 0,
    "refill": 10000,
    "interval": 100
  },
  "local_bucket": {
    "max": 100,
    "initial": 0
  }
}

An example of limiting the size and number of reads and writes to a tenant is as follows:

"request_config": {
  "data_in": {
    "remote_bucket": {
      "max": 10000,
      "initial": 0,
      "refill": 10000,
      "interval": 100
    },
    "local_bucket": {
      "max": 10000,
      "initial": 0
    }
  },
  "data_out": {
    "remote_bucket": {
      "max": 100,
      "initial": 0,
      "refill": 100,
      "interval": 100
     },
    "local_bucket": {
      "max": 100,
      "initial": 0
    }
  },
  "queries": null,
  "writes": null
}

Overall Example

create tenant test;
alter tenant test set _limiter = '{
  "object_config": {
    "max_users_number": 1,
    "max_databases": 3,
    "max_shard_number": 2,
    "max_replicate_number": 2,
    "max_retention_time": 30
  },
  "request_config": {
    "data_in": {
      "remote_bucket": {
        "max": 10000,
        "initial": 0,
        "refill": 10000,
        "interval": 100
      },
      "local_bucket": {
        "max": 10000,
        "initial": 0
     }
    },
     "data_out": {
       "remote_bucket": {
       "max": 100,
       "initial": 0,
        "refill": 100,
        "interval": 100
  },
  "local_bucket": {
    "max": 100,
    "initial": 0
  }
  },
  "queries": null,
  "writes": null
  }
}';