17.3.4.2. MySQL Server Options for MySQL Cluster

--ndb-batch-size=#

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

--ndb-cluster-connection-pool=#

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.

--ndb-blob-read-batch-bytes=bytes

This option can be used to set the size (in bytes) for batching of BLOB data reads in MySQL Cluster applications. When this batch size is exceeded by the amount of BLOB data to be read within the current transaction, any pending BLOB read operations are immediately executed.

The maximum value for this option is 4294967295; the default is 65535. Setting it to 0 has the effect of disabling BLOB read batching.

--ndb-blob-write-batch-bytes=bytes

This option can be used to set the size (in bytes) for batching of BLOB data writes in MySQL Cluster applications. When this batch size is exceeded by the amount of BLOB data to be written within the current transaction, any pending BLOB write operations are immediately executed.

The maximum value for this option is 4294967295; the default is 65535. Setting it to 0 has the effect of disabling BLOB write batching.

--ndb-connectstring=connect_string

When using the NDBCLUSTER storage engine, this option specifies the management server that distributes cluster configuration data. See Section 17.3.2.3, "The MySQL Cluster Connectstring", for syntax.

--ndb-deferred-constraints=[TRUE|FALSE]

Controls whether or not constraint checks on unique indexes are deferred until commit time, where such checks are supported. OFF is the default.

This option is not normally needed for operation of MySQL Cluster or MySQL Cluster Replication, and is intended primarily for use in testing.

--ndb-distribution=[KEYHASH|LINHASH]

Controls the default distribution method for NDB tables. Can be set to either of KEYHASH (key hashing) or LINHASH (linear hashing). KEYHASH is the default.

--ndb-mgmd-host=host[:port]

Can be used to set the host and port number of a single management server for the program to connect to. If the program requires node IDs or references to multiple management servers (or both) in its connection information, use the --ndb-connectstring option instead.

--ndbcluster

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-log-apply-status

Causes a slave mysqld to log any updates received from its immediate master to the mysql.ndb_apply_status table in its own binary log using its own server ID rather than the server ID of the master. In a circular or chain replication setting, this allows such updates to propagate to the mysql.ndb_apply_status tables of any MySQL servers configured as slaves of the current mysqld.

In a chain replication setup, using this option allows downstream (slave) clusters to be aware of their positions relative to all of their upstream contributors (masters).

In a circular replication setup, this option causes changes to ndb_apply_status tables to complete the entire circuit, eventually propagating back to the originating MySQL Cluster. This also allows a cluster acting as a master to see when its changes (epochs) have been applied to the other clusters in the circle.

This option has no effect unless the MySQL server is started with the --ndbcluster option.

--ndb-log-transaction-id

Causes a slave mysqld to write the NDB transaction ID in each row of the binary log. Such logging requires the use of the Version 2 event format for the binary log; thus, --log-bin-use-v1-row-events must be set to FALSE in order to use this option.

This option is not supported in mainline MySQL Server 5.6. It is required to enable MySQL Cluster Replication conflict detection and resolution using the NDB$EPOCH_TRANS() function (see NDB$EPOCH_TRANS()).

The default value is FALSE.

For more information, see Section 17.6.11, "MySQL Cluster Replication Conflict Resolution".

--ndb-nodeid=#

Set this MySQL server's node ID in a MySQL Cluster.

The --ndb-nodeid option overrides any node ID set with --ndb-connectstring, regardless of the order in which the two options are used.

In addition, if --ndb-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 a NodeId or Id parameter specified). This is also true if the node ID is specified as part of the connectstring.

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 17.3.2.7, "Defining SQL and Other API Nodes in a MySQL Cluster".

--ndb-log-empty-epochs=[0|1]

Causes epochs during which there were no changes to be written to the ndb_apply_status and ndb_binlog_index tables, even when --log-slave-updates is enabled.

By default this option is disabled. Disabling --ndb-log-empty-epochs causes epoch transactions with no changes not to be written to the binary log, although a row is still written even for an empty epoch in ndb_binlog_index.

Because --ndb-log-empty-epochs=1 causes the size of ndb_binlog_index table to increase independently of the size of the binary log, users should be prepared to manage the growth of this table, even if they expect the cluster to be idle a large part of the time.

--ndb-recv-thread-activation-threshold=threshold

When this number of concurrently active threads is reached, the receive thread takes over polling of the cluster connection.

--ndb-recv-thread-cpu-mask=bitmask

Set a CPU mask for locking receiver threads to specific CPUs. This is specified as a hexadecimal bitmask; for example, 0x33 means that one CPU is used per receiver thread. An empty string (no locking of receiver threads) is the default.

--server-id-bits=#

This option indicates the number of least significant bits within the 32-bit server_id which actually identify the server. Indicating that the server is actually identified by fewer than 32 bits makes it possible for some of the remaining bits to be used for other purposes, such as storing user data generated by applications using the NDB API's Event API within the AnyValue of an OperationOptions structure (MySQL Cluster uses the AnyValue to store the server ID).

When extracting the effective server ID from server_id for purposes such as detection of replication loops, the server ignores the remaining bits. The --server-id-bits option is used to mask out any irrelevant bits of server_id in the IO and SQL threads when deciding whether an event should be ignored based on the server ID.

This data can be read from the binary log by mysqlbinlog, provided that it is run with its own --server-id-bits option set to 32 (the default).

The value of server_id must be less than 2 ^ server_id_bits; otherwise, mysqld refuses to start.

This system variable is supported only by MySQL Cluster. It is not supported in the standard MySQL 5.6 Server.

--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 17.3.1, "Quick Test Setup of MySQL Cluster", for an example.

ndb-transid-mysql-connection-map=state

Enables or disables the plugin that handles the ndb_transid_mysql_connection_map table in the INFORMATION_SCHEMA database. Takes one of the values ON, OFF, or FORCE. ON (the default) enables the plugin. OFF disables the plugin, which makes ndb_transid_mysql_connection_map inaccessible. FORCE keeps the MySQL Server from starting if the plugin fails to load and start.

You can see whether the ndb_transid_mysql_connection_map table plugin is running by checking the output of SHOW PLUGINS.

--ndb-wait-connected=seconds

This option sets the period of time that the MySQL server waits for connections to MySQL Cluster management and data nodes to be established before accepting MySQL client connections. The time is specified in seconds. The default value is 30.

--ndb-wait-setup=seconds

This variable shows the period of time that the MySQL server waits for the NDB storage engine to complete setup before timing out and treating NDB as unavailable. The time is specified in seconds. The default value is 30.

--ndb_optimization_delay=milliseconds

Set the number of milliseconds to wait between sets of rows by OPTIMIZE TABLE statements on NDB tables. The default is 15.