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3.4.4. MySQL Cluster Status Variables

This section provides detailed information about MySQL server status variables that relate to MySQL Cluster and the NDB storage engine. For status variables not specific to MySQL Cluster, and for general information on using status variables, see Server Status Variables.

  • Handler_discover

    The MySQL server can ask the NDBCLUSTER storage engine if it knows about a table with a given name. This is called discovery. Handler_discover indicates the number of times that tables have been discovered via this mechanism.

  • Ndb_cluster_node_id

    If the server is acting as a MySQL Cluster node, then the value of this variable its node ID in the cluster.

    If the server is not part of a MySQL Cluster, then the value of this variable is 0.

  • Ndb_config_from_host

    If the server is part of a MySQL Cluster, the value of this variable is the host name or IP address of the Cluster management server from which it gets its configuration data.

    If the server is not part of a MySQL Cluster, then the value of this variable is an empty string.

    Prior to MySQL 5.1.12, this variable was named Ndb_connected_host.

  • Ndb_config_from_port

    If the server is part of a MySQL Cluster, the value of this variable is the number of the port through which it is connected to the Cluster management server from which it gets its configuration data.

    If the server is not part of a MySQL Cluster, then the value of this variable is 0.

    Prior to MySQL 5.1.12, this variable was named Ndb_connected_port.

  • Ndb_execute_count

    Provides the number of round trips to the NDB kernel made by operations. Added in MySQL Cluster NDB 6.3.6.

  • Ndb_number_of_data_nodes

    If the server is part of a MySQL Cluster, the value of this variable is the number of data nodes in the cluster.

    If the server is not part of a MySQL Cluster, then the value of this variable is 0.

    Prior to MySQL 5.1.12, this variable was named Ndb_number_of_storage_nodes.

  • Slave_heartbeat_period

    Shows the replication heartbeat interval (in seconds) on a replication slave.

    This variable was added in MySQL Cluster NDB 6.3.4.

  • Slave_received_heartbeats

    This counter increments with each replication heartbeat received by a replication slave since the last time that the slave was restarted or reset, or a CHANGE MASTER TO statement was issued.

    This variable was added in MySQL Cluster NDB 6.3.4.

  • Ndb_pruned_scan_count

    This variable holds a count of the number of scans executed by NDBCLUSTER since the MySQL Cluster was last started where NDBCLUSTER was able to use partition pruning.

    Using this variable together with Ndb_scan_count can be helpful in schema design to maximize the ability of the server to prune scans to a single table partition, thereby involving only a single data node.

    This variable was added in MySQL Cluster NDB 6.3.25 and MySQL Cluster NDB 7.0.5.

  • Ndb_scan_count

    This variable holds a count of the total number of scans executed by NDBCLUSTER since the MySQL Cluster was last started.

    This variable was added in MySQL Cluster NDB 6.3.25 and MySQL Cluster NDB 7.0.5.