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3.4.3 MySQL Cluster System Variables »
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3.4.2. mysqld Command Options for MySQL Cluster

This section provides descriptions of mysqld server options relating to MySQL Cluster. For information about mysqld options not specific to MySQL Cluster, and for general information about the use of options with mysqld, see Server Command Options.

For information about command-line options used with other MySQL Cluster processes (ndbd, ndb_mgmd, and ndb_mgm), see Section 4.23, “Options Common to MySQL Cluster Programs”. For information about command-line options used with NDB utility programs (such as ndb_desc, ndb_size.pl, and ndb_show_tables), see Chapter 4, MySQL Cluster Programs.

  • --ndb-batch-size=#

    Version Introduced 5.1.23-ndb-6.3.8
    Command-Line Format --ndb-batch-size
    Config-File Format ndb-batch-size
    Variable Name ndb_batch_size
    Variable Scope Global
    Dynamic Variable No
      Permitted Values
    Type numeric
    Default 32768
    Range 0-31536000

    This sets the size in bytes that is used for NDB transaction batches.

  • --ndb-cluster-connection-pool=#

    Version Introduced 5.1.19-ndb-6.2.2
    Command-Line Format --ndb-cluster-connection-pool
    Config-File Format ndb-cluster-connection-pool
    Variable Name Ndb_cluster_connection_pool
    Variable Scope Global
    Dynamic Variable No
      Permitted Values
    Type numeric
    Default 1
    Range 1-63

    By setting this option to a value greater than 1 (the default), a mysqld process can use multiple connections to the cluster, effectively mimicking several SQL nodes. Each connection requires its own [api] or [mysqld] section in the cluster configuration (config.ini) file, and counts against the maximum number of API connections supported by the cluster.

    Suppose that you have 2 cluster host computers, each running an SQL node whose mysqld process was started with --ndb-cluster-connection-pool=4; this means that the cluster must have 8 API slots available for these connections (instead of 2). All of these connections are set up when the SQL node connects to the cluster, and are allocated to threads in a round-robin fashion.

    This option is useful only when running mysqld on host machines having multiple CPUs, multiple cores, or both. For best results, the value should be smaller than the total number of cores available on the host machine. Setting it to a value greater than this is likely to degrade performance severely.

    Important

    Because each SQL node using connection pooling occupies multiple API node slots — each slot having its own node ID in the cluster — you must not use a node ID as part of the cluster connect string when starting any mysqld process that employs connection pooling.

    Setting a node ID in the connect string when using the --ndb-cluster-connection-pool option causes node ID allocation errors when the SQL node attempts to connect to the cluster.

    This option was introduced in MySQL Cluster NDB 6.2.2. Beginning with MySQL Cluster NDB 6.2.16 and MySQL Cluster NDB 6.3.13, the value used for this option is available as a global status variable (Bug#35573).

  • --ndb-connectstring=connect_string

    Command-Line Format --ndb-connectstring
    Config-File Format ndb-connectstring
      Permitted Values
    Type string

    When using the NDBCLUSTER storage engine, this option specifies the management server that distributes cluster configuration data. See Section 3.2.3, “The MySQL Cluster Connectstring”, for syntax.

  • --ndbcluster

    Command-Line Format --ndbcluster
    Config-File Format ndbcluster
    Option Sets Variable Yes, have_ndbcluster
    Disabled by skip-ndbcluster
      Permitted Values
    Type boolean
    Default FALSE

    The NDBCLUSTER storage engine is necessary for using MySQL Cluster. If a mysqld binary includes support for the NDBCLUSTER storage engine, the engine is disabled by default. Use the --ndbcluster option to enable it. Use --skip-ndbcluster to explicitly disable the engine.

  • --ndb-nodeid=#

    Version Introduced 5.1.15
    Command-Line Format --ndb-nodeid=#
    Config-File Format ndb-nodeid
    Variable Name Ndb_cluster_node_id
    Variable Scope Global
    Dynamic Variable No
      Permitted Values (>= 5.1.5)
    Type numeric
    Range 1-255

    Set this MySQL server's node ID in a MySQL Cluster. This can be used instead of specifying the node ID as part of the connectstring or in the config.ini file, or allowing the cluster to determine an arbitrary node ID. If you use this option, then --ndb-nodeid must be specified before --ndb-connectstring. If --ndb-nodeid is used and a node ID is specified in the connectstring, then the MySQL server will not be able to connect to the cluster. In addition, if --nodeid is used, then either a matching node ID must be found in a [mysqld] or [api] section of config.ini, or there must be an “open” [mysqld] or [api] section in the file (that is, a section without an Id parameter specified).

    Regardless of how the node ID is determined, its is shown as the value of the global status variable Ndb_cluster_node_id in the output of SHOW STATUS, and as cluster_node_id in the connection row of the output of SHOW ENGINE NDBCLUSTER STATUS.

    For more information about node IDs for MySQL Cluster SQL nodes, see Section 3.2.7, “Defining SQL and Other API Nodes in a MySQL Cluster”.

  • --skip-ndbcluster

    Command-Line Format --skip-ndbcluster
    Config-File Format skip-ndbcluster

    Disable the NDBCLUSTER storage engine. This is the default for binaries that were built with NDBCLUSTER storage engine support; the server allocates memory and other resources for this storage engine only if the --ndbcluster option is given explicitly. See Section 3.1, “Quick Test Setup of MySQL Cluster”, for an example.