Use Limits

Last updated: 2021-02-04 11:48:43


    Currently, WiredTiger and Rocks are supported. The latter is supported only in TencentDB for MongoDB v3.2.


    There are the following options when you create a TencentDB for MongoDB instance:

    Node Configuration Description
    Single node An instance has a single node and its specification is currently not customizable.
    Replica set An instance has 1 primary node and 2 secondary nodes.
    Sharded cluster An instance has at least 2 shards, and each shard has at least 3 nodes. You can expand the specifications of shard nodes, but cannot add shards or nodes.

    Limit on Number of Connections

    For a replica set, the maximum number of connections is subject to the memory size of a single node as shown below:

    Memory Specification Maximum Number of Connections
    2 GB 1,500
    4 GB 2,000
    6 GB 2,500
    8 GB 3,500
    16 GB 6,000
    24 GB 8,000
    32 GB 9,500
    64 GB 16,000
    128 GB 18,000
    240 GB 18,000
    512 GB 18,000


    • The above numbers of connections have taken effect since August 10, 2020.
    • For a sharded cluster, the maximum number of connections is the number of shards * specification of single shard or 18,000, whichever is smaller.
      For example, if a sharded cluster instance has 3 shards, each with 64 GB memory, then as 16,000 * 3 = 48,000 > 18,000, the maximum number of connections for this cluster will be 18,000.

    User Name for Instance Connection

    TencentDB for MongoDB comes with a default user: "mongouser". It supports the SCRAM-SHA-1 authentication mechanism, and its role is readWriteAnyDatabase+dbAdmin. You can use it to read and write any database, but are not permitted to perform high-risk operations.

    TencentDB for MongoDB v3.2 supports another default user: "rwuser". It uses the MONGODB-CR authentication mechanism which, however, has been no longer supported by MongoDB. We recommend using the "mongouser" to connect to your instance.

    You can also manage your account and permissions as needed in the TencentDB for MongoDB console.

    Avoiding Filling Up Disk

    When the disk usage of an instance has reached 100%, you cannot write to it. If this happens, please contact us for assistance. We recommend adjusting the instance specifications in time as needed. For more information, please see Adjusting Instance Specification.