mysqld 是传统的 MySQL 服务器进程。要与 NDB 集群一起使用，mysqld 需要构建时支持 NDB 存储引擎，这在从 https://dev.mysql.com/downloads/ 可获取的预编译二进制文件中已有。如果你从源码构建 MySQL，必须使用 CMake 并带上 -DWITH_NDB=1 或（已弃用的）-DWITH_NDBCLUSTER=1 选项来包含对 NDB 的支持。mysqld is the traditional MySQL server process. To be used with NDB Cluster, mysqld needs to be built with support for the NDB storage engine, as it is in the precompiled binaries available from https://dev.mysql.com/downloads/. If you build MySQL from source, you must invoke CMake with the -DWITH_NDB=1 or (deprecated) -DWITH_NDBCLUSTER=1 option to include support for NDB.

有关从源代码编译 NDB Cluster 的更多信息，请参见 第 25.3.1.4 节，“在 Linux 上从源代码构建 NDB Cluster”，以及 第 25.3.2.2 节，“在 Windows 上从源代码编译和安装 NDB Cluster”。For more information about compiling NDB Cluster from source, see Section 25.3.1.4, “Building NDB Cluster from Source on Linux”, and Section 25.3.2.2, “Compiling and Installing NDB Cluster from Source on Windows”.

（有关 mysqld 的选项和变量的信息，除了本节讨论的与 NDB Cluster 相关的内容外，请参见 第 25.4.3.9 节，“NDB Cluster 的 MySQL 服务器选项和变量”。）(For information about mysqld options and variables, in addition to those discussed in this section, which are relevant to NDB Cluster, see Section 25.4.3.9, “MySQL Server Options and Variables for NDB Cluster”.)

如果 mysqld 二进制文件已支持 Cluster，NDBCLUSTER 存储引擎默认仍然是禁用的。您可以使用以下两种方法中的任意一种来启用此引擎：If the mysqld binary has been built with Cluster support, the NDBCLUSTER storage engine is still disabled by default. You can use either of two possible options to enable this engine:

验证您的服务器是否启用了NDBCLUSTER存储引擎的一个简单方法是在 MySQL 监视器中 (mysql) 执行SHOW ENGINES语句。您应该在NDBCLUSTER行中看到Support列的值为YES。如果您看到此行的值为NO，或输出中没有显示此行，则说明您没有运行启用NDB的 MySQL 版本。如果您在此行看到DISABLED，则需要按照前面描述的两种方法之一启用它。An easy way to verify that your server is running with the NDBCLUSTER storage engine enabled is to issue the SHOW ENGINES statement in the MySQL Monitor (mysql). You should see the value YES as the Support value in the row for NDBCLUSTER. If you see NO in this row or if there is no such row displayed in the output, you are not running an NDB-enabled version of MySQL. If you see DISABLED in this row, you need to enable it in either one of the two ways just described.

要读取群集配置信息，MySQL 服务器至少需要三条信息：To read cluster configuration data, the MySQL server requires at a minimum three pieces of information:

节点 ID 可以动态分配，因此不必非要显式指定。Node IDs can be allocated dynamically, so it is not strictly necessary to specify them explicitly.

mysqld 参数 ndb-connectstring 用于在启动 mysqld 时在命令行上指定连接字符串，或者在 my.cnf 中指定。连接字符串包含管理服务器所在的主机名或 IP 地址，以及它使用的 TCP/IP 端口。The mysqld parameter ndb-connectstring is used to specify the connection string either on the command line when starting mysqld or in my.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.

在下面的示例中，ndb_mgmd.mysql.com 是管理服务器所在的主机，管理服务器在端口 1186 上监听集群消息：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

请参阅 第 25.4.3.3 节，“NDB 集群连接字符串”，了解有关连接字符串的更多信息。See Section 25.4.3.3, “NDB Cluster Connection Strings”, for more information on connection strings.

根据这些信息，MySQL 服务器可以作为集群的完整参与者。（我们通常将以这种方式运行的 mysqld 进程称为 SQL 节点。）它完全了解所有集群数据节点及其状态，并与所有数据节点建立连接。在这种情况下，它能够将任何数据节点用作事务协调器，并读取和更新节点数据。Given this information, the MySQL server can act as a full participant in the cluster. (We often refer to a mysqld 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.

您可以在 mysql 客户端中使用 SHOW PROCESSLIST 查看 MySQL 服务器是否已连接到集群。如果 MySQL 服务器已连接到集群，并且您拥有 PROCESS 权限，则输出的第一行如下所示：You can see in the mysql client whether a MySQL server is connected to the cluster using SHOW PROCESSLIST. If the MySQL server is connected to the cluster, and you have the PROCESS 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