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MySQL跨實(shí)例進(jìn)行數(shù)據(jù)查詢(xún)的項(xiàng)目實(shí)踐

更新時(shí)間：2025年05月09日 09:43:59 作者：DK_Allen

本文介紹了MySQL的FEDERATED引擎,該引擎允許在不切換數(shù)據(jù)庫(kù)實(shí)例的情況下進(jìn)行跨實(shí)例數(shù)據(jù)查詢(xún),具有一定的參考價(jià)值,感興趣的可以了解一下

前言：

在實(shí)際工作中，我們可能會(huì)遇到需要操作其他數(shù)據(jù)庫(kù)實(shí)例的部分表，但又不想系統(tǒng)連接多庫(kù)。此時(shí)我們就需要用到數(shù)據(jù)表映射。如同Oracle中的DBlink一般，使用過(guò)Oracle DBlink數(shù)據(jù)庫(kù)鏈接的人都知道可以跨實(shí)例來(lái)進(jìn)行數(shù)據(jù)查詢(xún)，同樣的，Mysql自帶的FEDERATED引擎完美的幫我們解決了該問(wèn)題。本篇文章介紹FEDERATED引擎的開(kāi)啟和使用。

1.開(kāi)啟FEDERATED引擎

若需要?jiǎng)?chuàng)建FEDERATED引擎表，則目標(biāo)端實(shí)例要開(kāi)啟FEDERATED引擎。從MySQL5.5開(kāi)始FEDERATED引擎默認(rèn)安裝只是沒(méi)有啟用，進(jìn)入命令行輸入 show engines; FEDERATED行狀態(tài)為NO。

mysql> show engines;

+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+

| Engine             | Support | Comment                                                        | Transactions | XA   | Savepoints |

+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+

| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |

| MRG_MYISAM         | YES     | Collection of identical MyISAM tables                          | NO           | NO   | NO         |

| CSV                | YES     | CSV storage engine                                             | NO           | NO   | NO         |

| BLACKHOLE          | YES     | /dev/null storage engine (anything you write to it disappears) | NO           | NO   | NO         |

| MyISAM             | YES     | MyISAM storage engine                                          | NO           | NO   | NO         |

| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |

| 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 (0.00 sec)

在配置文件[mysqld]中加入一行：federated，

然后重啟數(shù)據(jù)庫(kù)，F(xiàn)EDERATED引擎就開(kāi)啟了。

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         |

| PERFORMANCE_SCHEMA | YES     | Performance Schema                                             | NO           | NO   | NO         |

| MEMORY             | YES     | Hash based, stored in memory, useful for temporary tables      | NO           | NO   | NO         |

| ARCHIVE            | YES     | Archive storage engine                                         | NO           | NO   | NO         |

| InnoDB             | DEFAULT | Supports transactions, row-level locking, and foreign keys     | YES          | YES  | YES        |

| FEDERATED          | YES     | Federated MySQL storage engine                                 | NO           | NO   | NO         |

+--------------------+---------+----------------------------------------------------------------+--------------+------+------------+

9 rows in set (0.00 sec)

2.使用CONNECTION創(chuàng)建FEDERATED表

使用CONNECTION創(chuàng)建FEDERATED引擎表通用模型：

CREATE TABLE (......) 

ENGINE =FEDERATED CONNECTION='mysql://username:password@hostname:port/database/tablename'

簡(jiǎn)單創(chuàng)建測(cè)試：

# 源端表結(jié)構(gòu)及數(shù)據(jù)

mysql> show create table test_table\G

*************************** 1. row ***************************

       Table: test_table

Create Table: CREATE TABLE `test_table` (

  `increment_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '自增主鍵',

  `stu_id` int(11) NOT NULL COMMENT '學(xué)號(hào)',

  `stu_name` varchar(20) DEFAULT NULL COMMENT '學(xué)生姓名',

  `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創(chuàng)建時(shí)間',

  `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改時(shí)間',

  PRIMARY KEY (`increment_id`),

  UNIQUE KEY `uk_stu_id` (`stu_id`)

) ENGINE=InnoDB AUTO_INCREMENT=7 DEFAULT CHARSET=utf8 COMMENT='學(xué)生表'

1 row in set (0.00 sec)




mysql> select * from test_table;

+--------------+--------+----------+---------------------+---------------------+

| increment_id | stu_id | stu_name | create_time         | update_time         |

+--------------+--------+----------+---------------------+---------------------+

|            1 |   1001 | wang     | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            2 |   1002 | dfsfd    | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            3 |   1003 | fdgfg    | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            4 |   1004 | sdfsdf   | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            5 |   1005 | dsfsdg   | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            6 |   1006 | fgd      | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

+--------------+--------+----------+---------------------+---------------------+

6 rows in set (0.00 sec)




# 目標(biāo)端建表及查詢(xún)

# 注意ENGINE=FEDERATED CONNECTION后為源端地址 避免使用帶@的密碼

mysql> CREATE TABLE `test_table` (

    ->   `increment_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '自增主鍵',

    ->   `stu_id` int(11) NOT NULL COMMENT '學(xué)號(hào)',

    ->   `stu_name` varchar(20) DEFAULT NULL COMMENT '學(xué)生姓名',

    ->   `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創(chuàng)建時(shí)間',

    ->   `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改時(shí)間',

    ->   PRIMARY KEY (`increment_id`),

    ->   UNIQUE KEY `uk_stu_id` (`stu_id`)

    -> ) ENGINE=FEDERATED DEFAULT CHARSET=utf8 COMMENT='學(xué)生表' CONNECTION='mysql://root:root@10.50.60.212:3306/source/test_table';

Query OK, 0 rows affected (0.01 sec)




mysql> select * from test_table;

+--------------+--------+----------+---------------------+---------------------+

| increment_id | stu_id | stu_name | create_time         | update_time         |

+--------------+--------+----------+---------------------+---------------------+

|            1 |   1001 | wang     | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            2 |   1002 | dfsfd    | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            3 |   1003 | fdgfg    | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            4 |   1004 | sdfsdf   | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            5 |   1005 | dsfsdg   | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

|            6 |   1006 | fgd      | 2019-06-21 10:52:03 | 2019-06-21 10:52:03 |

+--------------+--------+----------+---------------------+---------------------+

6 rows in set (0.00 sec)

3.使用CREATE SERVER創(chuàng)建FEDERATED表

如果要在同一服務(wù)器上創(chuàng)建多個(gè)FEDERATED表，或者想簡(jiǎn)化創(chuàng)建FEDERATED表的過(guò)程，則可以使用該CREATE SERVER語(yǔ)句定義服務(wù)器連接參數(shù)，這樣多個(gè)表可以使用同一個(gè)server。

CREATE SERVER創(chuàng)建的格式是：

CREATE SERVER fedlink

FOREIGN DATA WRAPPER mysql

OPTIONS (USER 'fed_user', PASSWORD '123456', HOST 'remote_host', PORT 3306, DATABASE 'federated');

之后創(chuàng)建FEDERATED表可采用如下格式：

CREATE TABLE (......) 

ENGINE =FEDERATED CONNECTION='test_link/tablename'

示例演示：

# 目標(biāo)端創(chuàng)建指向源端的server

mysql> CREATE SERVER test_link

    ->   FOREIGN DATA WRAPPER mysql

    ->   OPTIONS (USER 'root', PASSWORD 'root',HOST '10.50.60.212',PORT 3306,DATABASE 'source');

Query OK, 1 row affected (0.00 sec)




mysql> select * from mysql.servers\G

*************************** 1. row ***************************

Server_name: test_link

       Host: 10.50.60.212

         Db: source

   Username: root

   Password: root

       Port: 3306

     Socket: 

    Wrapper: mysql

      Owner: 

1 row in set (0.00 sec)




# 目標(biāo)端創(chuàng)建FEDERATED表

mysql> CREATE TABLE `s1` (

    ->   `increment_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '自增主鍵',

    ->   `stu_id` int(11) NOT NULL COMMENT '學(xué)號(hào)',

    ->   `stu_name` varchar(20) DEFAULT NULL COMMENT '學(xué)生姓名',

    ->   `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創(chuàng)建時(shí)間',

    ->   `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改時(shí)間',

    ->   PRIMARY KEY (`increment_id`),

    ->   UNIQUE KEY `uk_stu_id` (`stu_id`)

    -> ) ENGINE=FEDERATED DEFAULT CHARSET=utf8 COMMENT='學(xué)生表' CONNECTION='test_link/s1';

Query OK, 0 rows affected (0.01 sec)




mysql> CREATE TABLE `s2` (

    ->   `increment_id` int(11) NOT NULL AUTO_INCREMENT COMMENT '自增主鍵',

    ->   `stu_id` int(11) NOT NULL COMMENT '學(xué)號(hào)',

    ->   `stu_name` varchar(20) DEFAULT NULL COMMENT '學(xué)生姓名',

    ->   `create_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT '創(chuàng)建時(shí)間',

    ->   `update_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '修改時(shí)間',

    ->   PRIMARY KEY (`increment_id`),

    ->   UNIQUE KEY `uk_stu_id` (`stu_id`)

    -> ) ENGINE=FEDERATED DEFAULT CHARSET=utf8 COMMENT='學(xué)生表' CONNECTION='test_link/s2';

Query OK, 0 rows affected (0.01 sec)

4.FEDERATED使用總結(jié)

基于MySQL5.7.23版本，筆者在源端及目標(biāo)端實(shí)驗(yàn)了多種DDL及DML，現(xiàn)簡(jiǎn)單總結(jié)如下，有興趣的同學(xué)可以試試看。

目標(biāo)端建表結(jié)構(gòu)可以與源端不一樣推薦與源端結(jié)構(gòu)一致
源端DDL語(yǔ)句更改表結(jié)構(gòu) 目標(biāo)端不會(huì)變化
源端DML語(yǔ)句目標(biāo)端查詢(xún)會(huì)同步
源端drop表目標(biāo)端結(jié)構(gòu)還在但無(wú)法查詢(xún)
目標(biāo)端不能執(zhí)行DDL語(yǔ)句
目標(biāo)端執(zhí)行DML語(yǔ)句源端數(shù)據(jù)也會(huì)變化
目標(biāo)端truncate表源端表數(shù)據(jù)也會(huì)被清空
目標(biāo)端drop表對(duì)源端無(wú)影響

5.FEDERATED引擎最佳實(shí)踐

目前FEDERATED引擎使用范圍還不多，若確實(shí)有跨實(shí)例訪(fǎng)問(wèn)的需求，建議做好規(guī)范，個(gè)人總結(jié)最佳實(shí)踐如下：

源端專(zhuān)門(mén)創(chuàng)建只讀權(quán)限的用戶(hù)來(lái)供目標(biāo)端使用。
目標(biāo)端建議用CREATE SERVER方式創(chuàng)建FEDERATED表。
FEDERATED表不宜太多，遷移時(shí)要特別注意。
目標(biāo)端應(yīng)該只做查詢(xún)使用，禁止在目標(biāo)端更改FEDERATED表。
建議目標(biāo)端表名及結(jié)構(gòu)和源端保持一致。
源端表結(jié)構(gòu)變更后目標(biāo)端要及時(shí)刪除重建。

參考：

https://dev.mysql.com/doc/refman/5.7/en/federated-create.html

https://dev.mysql.com/doc/refman/5.7/en/create-server.html

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