MySQL存储引擎--------Federated最佳实战

1. 背景

* 本地MySQL数据库要访问远程MySQL数据库的表中的数据, 必须通过FEDERATED存储引擎来实现.

　 * 有点类似Oracle中的数据库链接(DBLINK). 要允许这个存储引擎, 当构建MySQL时使用--with-federated-storage-engine来configure.

* 当创建一个FEDERATED表的时候, 服务器在数据库目录创建一个表定义文件. 文件由表的名字开始, 并有一个.frm扩展名.

* 无其它文件被创建, 因为实际的数据在一个远程数据库上.

2. 相关特性

　 * 允许本地访问远程 MySQL 数据库中表的数据

* 本地不存储任何数据文件

* 仅支持 MySQL 对 MySQL 的访问

* 不支持异构数据库的访问

* MySQL默认不开启Federated存储引擎

3. 环境

两个MySQL 5.7实例

　 serverA　3306

serverB 3307

[root@MySQL ~]# mysql -S /tmp/mysql.sock1 -p123456mysql: [Warning] Using a password on the command line interface can be insecure.Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 7Server version: 5.7.18 MySQL Community Server (GPL)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> select version();+-----------+| version() |+-----------+| 5.7.18    |+-----------+1 row in set (0.00 sec)[root@MySQL ~]# mysql -S /tmp/mysql.sock2 -p123456mysql: [Warning] Using a password on the command line interface can be insecure.Welcome to the MySQL monitor.  Commands end with ; or \g.Your MySQL connection id is 6Server version: 5.7.18 MySQL Community Server (GPL)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> select version();+-----------+| version() |+-----------+| 5.7.18    |+-----------+1 row in set (0.00 sec)

4. Federated存储引擎设置

* 查看Federated是否开启 [ FEDERATED 中Support状态NO表明引擎未开启 ]

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         || InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        || PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         || ARCHIVE            | YES     | Archive storage engine                                         | 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       |+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+9 rows in set (0.01 sec)

* 配置文件指定开启Federated存储引擎　[ /etc/my.cnf ]

[mysqld]federated

* 重启MySQL 再次查看 [ FEDERATED 中Support状态成YES表明引擎开启成功 ]

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         || InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        || PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         || ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         || MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         || FEDERATED          | YES     | Federated MySQL storage engine                                 | NO           | NO   | NO         |+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+9 rows in set (0.00 sec)

5. 部署

* 在ServerA上有一个数据库dbtestA，在ServerB上有数据库dbtestB，要在ServerB的数据库dbtestB上建立ServerA的数据库dbtestA上的表tabletestA的数据表链接remote_tabletestA，通过普通用户test连接。

* ServerA创建数据库

mysql> create database dbtestA;Query OK, 1 row affected (0.02 sec)

* ServerA在dbtestA数据库中创建tabletestA表

mysql> create table tabletestA(id INT PRIMARY KEY NOT NULL AUTO_INCREMENT)ENGINE=INNODB;Query OK, 0 rows affected (0.11 sec)

* ServerA中创建普通用户并授权dbtestA数据库相关权限

mysql> create user 'test'@'127.0.0.1' IDENTIFIED BY '123456';Query OK, 0 rows affected (0.00 sec)mysql> grant select on dbtestA.* to 'test'@'127.0.0.1';Query OK, 0 rows affected (0.00 sec)

* ServerB 中创建数据库 dbtestB

mysql> create database dbtestB;Query OK, 1 row affected (0.00 sec)

* ServerB 在dbtestB中创建链接表remote_tabletestA, 使用普通用户test

mysql> use dbtestB;Database changedmysql> create table remote_tabletestA(    -> id INT PRIMARY KEY NOT NULL AUTO_INCREMENT    -> )ENGINE=FEDERATED    -> CONNECTION='mysql://test:123456@127.0.0.1:3306/dbtestA/tabletestA';Query OK, 0 rows affected (0.09 sec)

* 在ServerA dbtestA库tableA表中插入数据

Database changedmysql> use dbtestA;Database changedmysql> insert into tabletestA select NULL;Query OK, 1 row affected (0.01 sec)Records: 1  Duplicates: 0  Warnings: 0mysql> insert into tabletestA select NULL;Query OK, 1 row affected (0.03 sec)Records: 1  Duplicates: 0  Warnings: 0mysql> insert into tabletestA select NULL;Query OK, 1 row affected (0.01 sec)Records: 1  Duplicates: 0  Warnings: 0mysql> select * from tabletestA;+----+| id |+----+|  1 ||  2 ||  3 |+----+3 rows in set (0.01 sec)

* ServerB dbtestB库链接表remote_tabletestA查看

mysql> use dbtestB;Database changedmysql> select * from remote_tabletestA;+----+| id |+----+|  1 ||  2 ||  3 |+----+3 rows in set (0.01 sec)

* ServerB服务器中查看链接表remote_tablestestA相关文件

　　 .frm 表定义文件　[ Federated链接库本地不产生数据文件 ]

[root@MySQL ~]# ll /data/mysql_data2/dbtestB/total 16-rw-r----- 1 mysql mysql   65 Jun 25 10:40 db.opt-rw-r----- 1 mysql mysql 8556 Jun 25 10:42 remote_tabletestA.frm

6. 总结

以需求驱动技术，技术本身没有优略之分，只有业务之分。