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3.2.9 MySQL Cluster TCP/IP Connections Using Direct Connections »
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3.2.8. MySQL Cluster TCP/IP Connections

TCP/IP is the default transport mechanism for all connections between nodes in a MySQL Cluster. Normally it is not necessary to define TCP/IP connections; MySQL Cluster automatically sets up such connections for all data nodes, management nodes, and SQL or API nodes.

Note

For an exception to this rule, see Section 3.2.9, “MySQL Cluster TCP/IP Connections Using Direct Connections”.

To override the default connection parameters, it is necessary to define a connection using one or more [tcp] sections in the config.ini file. Each [tcp] section explicitly defines a TCP/IP connection between two MySQL Cluster nodes, and must contain at a minimum the parameters NodeId1 and NodeId2, as well as any connection parameters to override.

It is also possible to change the default values for these parameters by setting them in the [tcp default] section.

Important

Any [tcp] sections in the config.ini file should be listed last, following all other sections in the file. However, this is not required for a [tcp default] section. This requirement is a known issue with the way in which the config.ini file is read by the MySQL Cluster management server.

Connection parameters which can be set in [tcp] and [tcp default] sections of the config.ini file are listed here:

  • NodeId1, NodeId2

    To identify a connection between two nodes it is necessary to provide their node IDs in the [tcp] section of the configuration file. These are the same unique Id values for each of these nodes as described in Section 3.2.7, “Defining SQL and Other API Nodes in a MySQL Cluster”.

  • OverloadLimit

    Beginning in MySQL Cluster NDB 6.4.0, this parameter can be used to determine the amount of unsent data that must be present in the send buffer before the connection is considered overloaded. See Section 3.2.13, “Configuring MySQL Cluster Send Buffer Parameters”, for more information.

  • SendBufferMemory

    Restart Type node
      Permitted Values
    Type numeric
    Default 256K
    Range 64K-4G

    TCP transporters use a buffer to store all messages before performing the send call to the operating system. When this buffer reaches 64KB its contents are sent; these are also sent when a round of messages have been executed. To handle temporary overload situations it is also possible to define a bigger send buffer.

    Prior to MySQL Cluster NDB 7.0, this parameter determined a fixed amount of memory allocated at startup for each configured TCP connection. Beginning with MySQL Cluster NDB 6.4.0, memory is not dedicated to each transporter. Instead, the value denotes the hard limit for how much memory (out of the total available memory — that is, TotalSendBufferMemory) that may be used by a single transporter. For more information about configuring dynamic transporter send buffer memory allocation in MySQL Cluster NDB 7.0 and later, see Section 3.2.13, “Configuring MySQL Cluster Send Buffer Parameters”.

    In MySQL Cluster NDB 6.4.3 and earlier, the default size of the send buffer was 256 KB; in MySQL Cluster NDB 7.0.4 and later, it is 2MB, which is the size recommended in most situations. The minimum size is 64 KB; the theoretical maximum is 4 GB.

  • SendSignalId

    Restart Type node
      Permitted Values
    Type boolean
    Default false (debug builds: true)
    Range -

    To be able to retrace a distributed message datagram, it is necessary to identify each message. When this parameter is set to Y, message IDs are transported over the network. This feature is disabled by default in production builds, and enabled in -debug builds.

  • Checksum

    Restart Type node
      Permitted Values
    Type boolean
    Default false
    Range -

    This parameter is a boolean parameter (enabled by setting it to Y or 1, disabled by setting it to N or 0). It is disabled by default. When it is enabled, checksums for all messages are calculated before they placed in the send buffer. This feature ensures that messages are not corrupted while waiting in the send buffer, or by the transport mechanism.

  • PortNumber (OBSOLETE)

    This formerly specified the port number to be used for listening for connections from other nodes. This parameter should no longer be used.

  • ReceiveBufferMemory

    Restart Type node
      Permitted Values
    Type numeric
    Default 64K
    Range 16K-4G

    Specifies the size of the buffer used when receiving data from the TCP/IP socket.

    In MySQL Cluster NDB 6.4.3 and earlier, the default value of this parameter was 64 KB; beginning with MySQL Cluster NDB 7.0.4, 2MB is the default. The minimum possible value is 16KB; the theoretical maximum is 4GB.