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mysqld is the traditional MySQL server process. To be used with NDB Cluster,mysqld needs to be built with support for theNDB storage engine, as it is in the precompiled binaries available fromhttps://dev.mysql.com/downloads/. If you build MySQL from source, you must invokeCMake with the-DWITH_NDB=1 or (deprecated)-DWITH_NDBCLUSTER=1 option to include support forNDB.

For more information about compiling NDB Cluster from source, seeSection 25.3.1.4, “Building NDB Cluster from Source on Linux”, andSection 25.3.2.2, “Compiling and Installing NDB Cluster from Source on Windows”.

(For information aboutmysqld options and variables, in addition to those discussed in this section, which are relevant to NDB Cluster, seeSection 25.4.3.9, “MySQL Server Options and Variables for NDB Cluster”.)

If themysqld binary has been built with Cluster support, theNDBCLUSTER storage engine is still disabled by default. You can use either of two possible options to enable this engine:

An easy way to verify that your server is running with theNDBCLUSTER storage engine enabled is to issue theSHOW ENGINES statement in the MySQL Monitor (mysql). You should see the valueYES as theSupport value in the row forNDBCLUSTER. If you seeNO in this row or if there is no such row displayed in the output, you are not running anNDB-enabled version of MySQL. If you seeDISABLED in this row, you need to enable it in either one of the two ways just described.

To read cluster configuration data, the MySQL server requires at a minimum three pieces of information:

Node IDs can be allocated dynamically, so it is not strictly necessary to specify them explicitly.

Themysqld parameterndb-connectstring is used to specify the connection string either on the command line when startingmysqld or inmy.cnf. The connection string contains the host name or IP address where the management server can be found, as well as the TCP/IP port it uses.

In the following example,ndb_mgmd.mysql.com is the host where the management server resides, and the management server listens for cluster messages on port 1186:

$> mysqld --ndbcluster --ndb-connectstring=ndb_mgmd.mysql.com:1186

SeeSection 25.4.3.3, “NDB Cluster Connection Strings”, for more information on connection strings.

Given this information, the MySQL server can act as a full participant in the cluster. (We often refer to amysqld process running in this manner as an SQL node.) It is fully aware of all cluster data nodes as well as their status, and establishes connections to all data nodes. In this case, it is able to use any data node as a transaction coordinator and to read and update node data.

You can see in themysql client whether a MySQL server is connected to the cluster usingSHOW PROCESSLIST. If the MySQL server is connected to the cluster, and you have thePROCESS privilege, then the first row of the output is as shown here:

mysql> SHOW PROCESSLIST \G*************************** 1. row ***************************     Id: 1   User: system user   Host:     db:Command: Daemon   Time: 1  State: Waiting for event from ndbcluster   Info: NULL