参考 https://blog.csdn.net/WYB213080286/article/details/38493753

参照以下博客：http://blog.csdn.net/renfengjun/article/details/18730977

最近项目中涉及MySQL数据库视图的创建，需要整合两个位于不同服务器上数据库的内容，就遇到了远程访问数据库的问题。在cracle中可以通过dblink来实现跨本地数据库来访问另外一个数据库中的数据。通过在网上查找，发现可以通过MySQL中的federated插件来实现类似的功能。

操作环境：

宿主机为win8系统，MySQL数据库，ip：192.168.1.98；从机为VMware虚拟机中的Linux系统，版本为CentOS6.5，MySQL数据库，ip：192.168.1.106。

实现功能：

可以在Linux系统中MySQL数据库（target端）中建立宿主机MySQL数据库（source端）中某个表的link，当在Linux中读取link表时，就相当于直接读取宿主机中的原始表内容。

实现步骤：

mysql> show engines;

±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+ | Engine | Support | Comment | Transactions | XA | Savepoints | ±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+ | CSV | YES | CSV storage engine | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | FEDERATED | NO | Federated MySQL storage engine | NULL | NULL | NULL | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | ±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+

显示没有安装federated插件

mysql>install plugin federated soname ‘ha_federated.so’;

ERROR 1125 (HY000): Function ‘federated’ already exists

说明已经安装过了，但没有启用

[root@localhost etc]# service mysql stop

[root@localhost etc]# mysqld_safe --federated &

[root@localhost etc]# 140811 01:20:21 mysqld_safe Logging to ‘/var/lib/mysql/localhost.localdomain.err’. 140811 01:20:22 mysqld_safe Starting mysqld daemon with databases from /var/lib/mysql

mysql> show engines;

±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+ | Engine | Support | Comment | Transactions | XA | Savepoints | ±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+ | CSV | YES | CSV storage engine | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | FEDERATED |YES | Federated MySQL storage engine | NULL | NULL | NULL | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | ±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+

federated插件已经启用

[root@localhost etc]# vi /etc/my.conf

在文件中加入一行：

federated

重启mysql服务

service mysql restart

mysql> show engines;

±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+ | Engine | Support | Comment | Transactions | XA | Savepoints | ±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+ | CSV | YES | CSV storage engine | NO | NO | NO | | MRG_MYISAM | YES | Collection of identical MyISAM tables | NO | NO | NO | | MyISAM | YES | MyISAM storage engine | NO | NO | NO | | BLACKHOLE | YES | /dev/null storage engine (anything you write to it disappears) | NO | NO | NO | | MEMORY | YES | Hash based, stored in memory, useful for temporary tables | NO | NO | NO | | FEDERATED | YES | Federated MySQL storage engine | NULL | NULL | NULL | | ARCHIVE | YES | Archive storage engine | NO | NO | NO | | InnoDB | DEFAULT | Supports transactions, row-level locking, and foreign keys | YES | YES | YES | | PERFORMANCE_SCHEMA | YES | Performance Schema | NO | NO | NO | ±-------------------±--------±---------------------------------------------------------------±-------------±-----±-----------+

已经设置为默认启动了。

DROP TABLE IF EXISTS e_eledata; CREATE TABLE e_eledata ( ID bigint(20) unsigned NOT NULL auto_increment COMMENT ‘ID’, E_ELEMETERHEAD_ID bigint(20) default NULL COMMENT ‘电表表头ID’, DAQDT timestamp NULL default NULL COMMENT ‘数据采集时间’, DLDT timestamp NULL default NULL COMMENT ‘数据入库时间’, APCURRENT decimal(10,3) default NULL COMMENT ‘A相电流。单位：A。’, BPCURRENT decimal(10,3) default NULL COMMENT ‘B相电流。单位：A。’, CPCURRENT decimal(10,3) default NULL COMMENT ‘C相电流。单位：A。’, APVOLTAGE decimal(10,3) default NULL COMMENT ‘A相电压。单位：V。’, BPVOLTAGE decimal(10,3) default NULL COMMENT ‘B相电压。单位：V。’, CPVOLTAGE decimal(10,3) default NULL COMMENT ‘C相电压。单位：V。’, PRIMARY KEY (ID) ) ENGINE=MyISAM AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COMMENT=‘电路数据表’;

DROP TABLE IF EXISTS e_eledata_link; CREATE TABLE e_eledata_link ( ID bigint(20) unsigned NOT NULL auto_increment COMMENT ‘ID’, E_ELEMETERHEAD_ID bigint(20) default NULL COMMENT ‘电表表头ID’, DAQDT timestamp NULL default NULL COMMENT ‘数据采集时间’, DLDT timestamp NULL default NULL COMMENT ‘数据入库时间’, APCURRENT decimal(10,3) default NULL COMMENT ‘A相电流。单位：A。’, BPCURRENT decimal(10,3) default NULL COMMENT ‘B相电流。单位：A。’, CPCURRENT decimal(10,3) default NULL COMMENT ‘C相电流。单位：A。’, APVOLTAGE decimal(10,3) default NULL COMMENT ‘A相电压。单位：V。’, BPVOLTAGE decimal(10,3) default NULL COMMENT ‘B相电压。单位：V。’, CPVOLTAGE decimal(10,3) default NULL COMMENT ‘C相电压。单位：V。’, PRIMARY KEY (ID) ) ENGINE=FEDERATEDAUTO_INCREMENT=1DEFAULT CHARSET=utf8 COMMENT=‘电路数据表’

CONNECTION='mysql://usrname:[email protected]:3306/databasename/table

其中：

usrname为宿主机中MySQL的用户名

password为相应的密码

（要保证该用户具有远程登陆的权限，可以通过以下命令来设置：

mysql>GRANT ALL PRIVILEGES ON . TO ‘usrname’@’%’ IDENTIFIED BY ‘password’ WITH GRANT OPTION;

其中*.*是指对用户开放所有数据库和表的权限，如果只开放某一个数据库的一个表为databasename.table；’%‘指的是该用户可以从任意的一个ip地址来远程访问数据库，包括本地，如果要限制用户从特定的ip来访问，将其改为’ip地址’）

192.168.1.98是source数据库的ip，这里为我宿主机的ip

3306为数据库的端口，默认一般为3306

database 和table分别为source端数据库的名称和表名称

将该sql脚本在target端运行

在target端通过访问e_eledata_link表来访问source端e_eledata表

mysql> select *from e_eledata_link;