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mysql中间件proxysql实现mysql读写分离

2019-03-13 17:21 537 查看

mysql中间件proxysql实现mysql读写分离

  • 6. 多层配置系统
  • 7. 不同类型的读写分离方案解析
  • 8. ProxySQL实现多主多从读写分离示例
  • 8.3 验证读写分离

    • 1. mysql实现读写分离的方式

    mysql 实现读写分离的方式有以下几种：

    • 程序修改mysql操作，直接和数据库通信，简单快捷的读写分离和随机的方式实现的负载均衡，权限独立分配，需要开发人员协助。
    • amoeba，直接实现读写分离和负载均衡，不用修改代码，有很灵活的数据解决方案，自己分配账户，和后端数据库权限管理独立，权限处理不够灵活。
    • mysql-proxy，直接实现读写分离和负载均衡，不用修改代码，master和slave用一样的帐号，效率低
    • mycat中间件
    • proxysql中间件（推荐使用）

    2. ProxySQL简介

    ProxySQL 是一款可以实际用于生产环境的 MySQL 中间件，它有官方版和 percona 版两种。percona版是在官方版的基础上修改的，添加了几个比较实用的工具。生产环境建议用官方版。

    ProxySQL 是用 C++ 语言开发的，虽然也是一个轻量级产品，但性能很好(据测试，能处理千亿级的数据)，功能也足够，能满足中间件所需的绝大多数功能，包括：

    • 最基本的读/写分离，且方式有多种
    • 可定制基于用户、基于schema、基于语句的规则对SQL语句进行路由。换句话说，规则很灵活。基于schema和与语句级的规则，可以实现简单的sharding(分库分表)
    • 可缓存查询结果。虽然ProxySQL的缓存策略比较简陋，但实现了基本的缓存功能，绝大多数时候也够用了。此外，作者已经打算实现更丰富的缓存策略
    • 监控后端节点。ProxySQL可以监控后端节点的多个指标，包括：ProxySQL和后端的心跳信息，后端节点的read-only/read-write，slave和master的数据同步延迟性(replication lag)

    3. ProxySQL安装

    //配置yum源
[root@localhost ~]# cd /etc/yum.repos.d/
[root@localhost yum.repos.d]# ls
redhat.repo  xx.repo
[root@localhost yum.repos.d]# yum -y install mariadb
[root@localhost yum.repos.d]# cat <<EOF | tee /etc/yum.repos.d/proxysql.repo
> [proxysql_repo]
> name= ProxySQL
> baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/7
> gpgcheck=1
> gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key
> EOF
[proxysql_repo]
name= ProxySQL
baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/7
gpgcheck=1
gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key

//安装proxysql
[root@localhost ~]# yum -y install proxysql

    4. ProxySQL的Admin管理接口

    当 ProxySQL 启动后，将监听两个端口：

    • admin管理接口，默认端口为6032。该端口用于查看、配置ProxySQL
    • 接收SQL语句的接口，默认端口为6033，这个接口类似于MySQL的3306端口

      ProxySQL 的 admin 管理接口是一个使用 MySQL 协议的接口，所以，可以直接使用 mysql 客户端、navicat 等工具去连接这个管理接口，其默认的用户名和密码均为 admin

    例如，使用 mysql 客户端去连接 ProxySQL 的管理接口：

    //开启proxysql
[root@localhost ~]# service proxysql start
Starting ProxySQL: 2019-03-13 14:34:45 [INFO] Using config file /etc/proxysql.cnf
DONE!
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]>show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | disk          | /var/lib/proxysql/proxysql.db       |
| 3   | stats         |                                     |
| 4   | monitor       |                                     |
| 5   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
5 rows in set (0.00 sec)

    由于 ProxySQL 的配置全部保存在几个自带的库中，所以通过管理接口，可以非常方便地通过发送一些SQL命令去修改 ProxySQL 的配置。 ProxySQL 会解析通过该接口发送的某些对ProxySQL 有效的特定命令，并将其合理转换后发送给内嵌的 SQLite3 数据库引擎去运行

    ProxySQL 的配置几乎都是通过管理接口来操作的，通过 Admin 管理接口，可以在线修改几乎所有的配置并使其生效。只有两个变量的配置是必须重启 ProxySQL 才能生效的，它们是：
    mysql-threads 和 mysql-stacksize

    5. 和admin管理接口相关的变量

    5.1 admin-admin_credentials

    admin-admin_credentials 变量控制的是admin管理接口的管理员账户。默认的管理员账户和密码为admin:admin，但是这个默认的用户只能在本地使用。如果想要远程连接到ProxySQL，例如用windows上的navicat连接Linux上的ProxySQL管理接口，必须自定义一个管理员账户。

    添加管理员帐户

    MySQL [(none)]> select @@admin-admin_credentials;			//查看当前用户名和密码
+---------------------------+
| @@admin-admin_credentials |
+---------------------------+
| admin:admin               |
+---------------------------+
1 row in set (0.00 sec)

//设置管理员帐号zml,密码123456
MySQL [(none)]> set admin-admin_credentials='admin:admin;zml:123456';
Query OK, 1 row affected (0.00 sec)

MySQL [(none)]> select @@admin-admin_credentials;
+---------------------------+
| @@admin-admin_credentials |
+---------------------------+
| admin:admin;zml:123456    |
+---------------------------+
1 row in set (0.00 sec)

//使修改立即生效（修改之后立即在系统中生效）
MySQL [(none)]> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

//使修改永久保存到磁盘（如果不保存到磁盘，则服务重启失效）
MySQL [(none)]> save admin variables to disk;
Query OK, 31 rows affected (0.01 sec)

MySQL [(none)]> exit
Bye

    修改后，就可以使用该用户名和密码连接管理接口

    [root@localhost ~]# mysql -uzml -p123456 -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 3
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]>

    所有的配置操作都是在修改main库中对应的表

    MySQL [(none)]> show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | disk          | /var/lib/proxysql/proxysql.db       |
| 3   | stats         |                                     |
| 4   | monitor       |                                     |
| 5   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
5 rows in set (0.00 sec)

MySQL [(none)]> use main;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
MySQL [main]> show tables;
+--------------------------------------------+
| tables                                     |
+--------------------------------------------+
| global_variables                           |
| mysql_collations                           |
| mysql_group_replication_hostgroups         |
| mysql_query_rules                          |
| mysql_query_rules_fast_routing             |
| mysql_replication_hostgroups               |
| mysql_servers                              |
| mysql_users                                |
| proxysql_servers                           |
| runtime_checksums_values                   |
| runtime_global_variables                   |
| runtime_mysql_group_replication_hostgroups |
| runtime_mysql_query_rules                  |
| runtime_mysql_query_rules_fast_routing     |
| runtime_mysql_replication_hostgroups       |
| runtime_mysql_servers                      |
| runtime_mysql_users                        |
| runtime_proxysql_servers                   |
| runtime_scheduler                          |
| scheduler                                  |
+--------------------------------------------+
20 rows in set (0.01 sec)

MySQL [main]> select * from global_variables where variable_name='admin-admin_credentials';
+-------------------------+------------------------+
| variable_name           | variable_value         |
+-------------------------+------------------------+
| admin-admin_credentials | admin:admin;zml:123456 |
+-------------------------+------------------------+
1 row in set (0.00 sec)

    必须要区分admin管理接口的用户名和mysql_users中的用户名

    • admin管理接口的用户是连接到管理接口(默认端口6032)上用来管理、配置ProxySQL的
    • mysql_users表中的用户名是应用程序连接ProxySQL(默认端口6033)，以及ProxySQL连接后端MySQL Servers使用的用户。它的作用是发送、路由SQL语句，类似于MySQL Server的3306端口。所以，这个表中的用户必须已经在后端MySQL Server上存在且授权了
      admin管理接口的用户必须不能存在于mysql_users中，这是出于安全的考虑，防止通过admin管理接口用户猜出mysql_users中的用户

    5.2 admin-stats_credentials

    admin-stats_credentials 变量控制admin管理接口的普通用户，这个变量中的用户没有超级管理员权限，只能查看monitor库和main库中关于统计的数据，其它库都是不可见的，且没有任何写权限

    默认的普通用户名和密码均为 stats ，与admin一样，它默认也只能用于本地登录，若想让人远程查看则要添加查看的专有用户

    MySQL [main]> select @@admin-stats_credentials;			//查看当前用户名和密码
+---------------------------+
| @@admin-stats_credentials |
+---------------------------+
| stats:stats               |
+---------------------------+
1 row in set (0.00 sec)

//设置普通用户zqq,密码123456
MySQL [main]> set admin-stats_credentials='stats:stats;zqq:123456';
Query OK, 1 row affected (0.00 sec)

//使修改立即生效
MySQL [main]> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

//使修改永久保存到磁盘
MySQL [main]> save admin variables to disk;
Query OK, 31 rows affected (0.01 sec)

MySQL [main]> select * from global_variables where variable_name='admin-stats_credentials';
+-------------------------+------------------------+
| variable_name           | variable_value         |
+-------------------------+------------------------+
| admin-stats_credentials | stats:stats;zqq:123456 |
+-------------------------+------------------------+
1 row in set (0.00 sec)

    同样，这个变量中的用户必须不能存在于mysql_users表中
    使用mystats用户远程连接查看

    [root@localhost ~]# mysql -uzqq -p123456 -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 4
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]> select @@admin-admin_cretentials;
ERROR 1045 (#2800): no such table: stats.stats_mysql_global
MySQL [(none)]> show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | monitor       |                                     |
| 3   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
3 rows in set (0.00 sec)

    5.3 admin-mysql_ifaces

    admin-mysql_ifaces 变量指定admin接口的监听地址，格式为冒号分隔的hostname:port列表。默认监听在 0.0.0.0:6032

    注意，允许使用UNIX的domain socket进行监听，这样本主机内的应用程序就可以直接被处理。
    例如：

    //可以改变端口
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 6
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]> set admin-mysql_ifaces='0.0.0.0:8888';
Query OK, 1 row affected (0.00 sec)

MySQL [(none)]> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> exit
Bye
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
ERROR 2003 (HY000): Can't connect to MySQL server on '127.0.0.1' (111)
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P8888
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 7
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]> set admin-mysql_ifaces='0.0.0.0:6032';
Query OK, 1 row affected (0.00 sec)

MySQL [(none)]> load admin variables to runtime;
Query OK, 0 rows affected (0.00 sec)

MySQL [(none)]> exit
Bye
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P8888
ERROR 2003 (HY000): Can't connect to MySQL server on '127.0.0.1' (111)
[root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 8
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

    6. 多层配置系统

    6.1 proxysql中的库

    使用ProxySQL的Admin管理接口连上ProxySQL，可查看ProxySQL拥有的库

    [root@localhost ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 9
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MySQL [(none)]> show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | disk          | /var/lib/proxysql/proxysql.db       |
| 3   | stats         |                                     |
| 4   | monitor       |                                     |
| 5   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
5 rows in set (0.00 sec)

    其中：

    • main库是ProxySQL最主要的库，是需要修改配置时使用的库，它其实是一个内存数据库系统。所以，修改main库中的配置后，必须将其持久化到disk上才能永久保存
    • disk库是磁盘数据库，该数据库结构和内存数据库完全一致。当持久化内存数据库中的配置时，其实就是写入到disk库中。磁盘数据库的默认路径为 $DATADIR/proxysql.db
    • stats库是统计信息库。这个库中的数据一般是在检索其内数据时临时填充的，它保存在内存中。因为没有相关的配置项，所以无需持久化
    • monitor库是监控后端MySQL节点相关的库，该库中只有几个log类的表，监控模块收集到的监控信息全都存放到对应的log表中
    • stats_history库是1.4.4版新增的库，用于存放历史统计数据。默认路径为 $DATADIR/proxysql_stats.db

    ProxySQL 内部使用的是 SQLite3 数据库，无论是内存数据库还是磁盘数据库，都是通过SQLite3引 擎进行解析、操作的。它和 MySQL 的语法可能稍有不同，但ProxySQL会对不兼容的语法自动进行调整，最大程度上保证MySQL语句的有效率。
    上面描述main库的时候，只是说了内存数据库需要持久化到disk库才能永久保存配置。但实际上，修改了main库中的配置后，并不会立即生效，它还需要load到runtime的数据结构中才生效，只有在runtime数据结构中的配置才是对ProxySQL当前有效的配置

    6.2 ProxySQL多层配置系统

    ProxySQL 的配置系统非常强大，它能在线修改几乎所有配置(仅有的两个需要重启才能生效的变量为 mysql-threads 和 mysql-stacksize )，并在线生效、持久化保存。这得益于它采用的多层配置系统。
    多层配置系统结构如下：

    +-------------------------+
|         RUNTIME         |
+-------------------------+
/|\          |
|           |
[1] |       [2] |
|          \|/
+-------------------------+
|         MEMORY          |
+-------------------------+ _
/|\          |      |\
|           |        \
[3] |       [4] |         \ [5]
|          \|/         \
+-------------------------+  +---------------+
|          DISK           |  |  CONFIG FILE  |
+-------------------------+  +---------------+

    最底层的是 disk 库和 config file 。这里需要注意，这里的 config file 就是传统的配置文件，默认为 /etc/proxysql.cnf ， ProxySQL 启动时，主要是从 disk 库中读取配置加载到内存并最终加载到 runtime 生效，只有极少的几个特定配置内容是从 config file 中加载的，除非是第一次初始化 ProxySQL 运行环境(或者disk库为空)。

    中间层的是 memory ，表示的是内存数据库，其实就是 main 库。通过管理接口修改的所有配置，都保存在内存数据库(main)中。当 ProxySQL 重启或者崩溃时，这个内存数据库中的数据会丢失，所以需要 save 到 disk 库中。

    最上层的是 runtime ，它是 ProxySQL 有关线程运行时读取的数据结构。换句话说，该数据结构中的配置都是已生效的配置。所以，修改了 main 库中的配置后，必须 load 到 runtime 数据结构中才能使其生效。
    在上面的多层配置系统图中，标注了[1]、[2]、[3]、[4]、[5]的序号。每个序号都有两个操作方向from/to，其实只是所站角度不同而已。以下是各序号对应的操作：

    [1] ：将内存数据库中的配置加载到RUNTIME数据结构中
LOAD XXX FROM MEMORY
LOAD XXX TO RUNTIME

[2] ：将RUNTIME数据结构中的配置持久化到内存数据库中
SAVE XXX FROM RUNTIME
SAVE XXX TO MEMORY

[3] ：将磁盘数据库中的配置加载到内存数据库中
LOAD XXX FROM DISK
LOAD XXX TO MEMORY

[4] ：将内存数据库中的配置持久化到磁盘数据库中
SAVE XXX FROM MEMORY
SAVE XXX TO DISK

[5] ：从传统配置文件中读取配置加载到内存数据库中
LOAD XXX FROM CONFIG

    DISK/MEMORY/RUNTIME/CONFIG 可以缩写，只要能识别即可。例如MEMORY可以缩写为MEM，runtime可以缩写为run

    另外，上面的XXX是什么？这表示要加载/保存的是哪类配置。目前的ProxySQL支持以下几种：

    • mysql users
    • mysql servers
    • mysql variables
    • mysql query rules
    • admin variables
    • scheduler
    • proxysql_servers：目前ProxySQL集群功能还处于实验阶段，所以该类配置不应该去使用

    这些从main库或disk库中就可以查看到

    MySQL [(none)]> show tables from disk;
+------------------------------------+
| tables                             |
+------------------------------------+
| global_variables                   |  # (1)
| mysql_collations                   |  # (N)
| mysql_group_replication_hostgroups |  # (2)
| mysql_query_rules                  |  # (3)
| mysql_query_rules_fast_routing     |  # (4)
| mysql_replication_hostgroups       |  # (5)
| mysql_servers                      |  # (6)
| mysql_users                        |  # (7)
| proxysql_servers                   |  # (8)
| scheduler                          |  # (9)
+------------------------------------+
10 rows in set (0.00 sec)

    上面的结果中我给这些表都标注了一些序号，其所对应的表的内容有以下讲究：

    • (1)中包含两类变量，以amdin-开头的表示admin variables，以mysql-开头的表示mysql variables。修改哪类变量，前文的XXX就代表哪类
    • (2,5,6)对应的都是mysql servers
    • (3,4)对应的是mysql query rules
    • (7)对应的mysql users
    • (9)对应的scheduler
    • (N)只是一张表，保存的是ProxySQL支持的字符集和排序规则，它是不用修改的
    • (8)是ProxySQL的集群配置表，该功能目前还处于实验阶段。如果想要配置该功能，则load/save proxysql_servers to/from …

    6.3 启动ProxySQL时如何加载配置

    如果 ProxySQL 是刚安装的，或者磁盘数据库文件为空(甚至不存在)，或者启动 ProxySQL 时使用了选项 --initial，这几种情况启动 ProxySQL 时，都会从传统配置文件 config file 中读取配置加载到内存数据库，并自动 load 到 runtime 数据结构、save到磁盘数据库，这是初始化 ProxySQL 运行环境的过程。

    如果不是第一次启动 ProxySQL ，由于已经存在磁盘数据库文件，这时 ProxySQL 会从磁盘数据库中读取几乎所有的配置(即使传统配置文件中配置了某项，也不会去解析)，但有3项是必须从传统配置文件中读取，它们分别是：

    • datadir：ProxySQL启动时，必须从配置文件中确定它的数据目录，因为磁盘数据库文件、日志以及其它一些文件是存放在数据目录下的。如果使用/etc/init.d/proxysql管理ProxySQL，则除了修改/etc/proxysql.cnf的datadir，还需要修改该脚本中的datadir。
    • restart_on_missing_heartbeats：MySQL线程丢失多少次心跳，就会杀掉这个线程并重启它。默认值为10。
    • execute_on_exit_failure：如果设置了该变量，ProxySQL父进程将在每次ProxySQL崩溃的时候执行已经定义好的脚本。建议使用它来生成一些崩溃时的警告和日志。注意，ProxySQL的重启速度可能只有几毫秒，因此很多其它的监控工具可能无法探测到ProxySQL的一次普通故障，此时可使用该变量

    7. 不同类型的读写分离方案解析

    数据库中间件最基本的功能就是实现读写分离， ProxySQL 当然也支持。而且 ProxySQL 支持的路由规则非常灵活，不仅可以实现最简单的读写分离，还可以将读/写都分散到多个不同的组，以及实现分库 sharding (分表sharding的规则比较难写，但也能实现)。

    本文只描述通过规则制定的语句级读写分离，不讨论通过 ip/port, client, username, schemaname 实现的读写分离。

    下面描述了ProxySQL能实现的常见读写分离类型

    7.1 最简单的读写分离


    这种模式的读写分离，严格区分后端的master和slave节点，且slave节点必须设置选项read_only=1

    在ProxySQL上，分两个组，一个写组HG=10，一个读组HG=20。同时在ProxySQL上开启monitor模块的read_only监控功能，让ProxySQL根据监控到的read_only值来自动调整节点放在HG=10(master会放进这个组)还是HG=20(slave会放进这个组)

    这种模式的读写分离是最简单的，只需在mysql_users表中设置用户的默认路由组为写组HG=10，并在mysql_query_rules中加上两条简单的规则(一个select for update，一个select)即可

    这种读写分离模式，在环境较小时能满足绝大多数需求。但是需求复杂、环境较大时，这种模式就太过死板，因为一切都是monitor模块控制的

    7.2 多个读组或写组的分离模式

    前面那种读写分离模式，是通过 monitor 模块监控 read_only 来调整的，所以每一个后端集群必须只能分为一个写组，一个读组。
    但如果想要区分不同的 select ，并将不同的 select 路由到不同的节点上。例如有些查询语句的开销非常大，想让它们独占一个节点/组，其它查询共享一个节点/组，怎么实现？

    例如，下面这种模式

    看上去非常简单。但是却能适应各种需求。例如，后端做了分库，对某库的查询要路由到特定的主机组

    至于各个主机组是同一个主从集群(下图左边)，还是互相独立的主从集群环境(下图右边)，要看具体的需求，不过这种读写分离模式都能应付

    在实现这种模式时，前提是不能开启monitor模块的read_only监控功能，也不要设置mysql_replication_hostgroup 表

    例如，下面的配置实现的是上图左边的结构：写请求路由给HG=10，对test1库的select语句路由给HG=20，其它select路由给HG=30

    mysql_servers:
+--------------+----------+------+--------+--------+
| hostgroup_id | hostname | port | status | weight |
+--------------+----------+------+--------+--------+
| 10           | host1    | 3306 | ONLINE | 1      |
| 20           | host2    | 3306 | ONLINE | 1      |
| 30           | host3    | 3306 | ONLINE | 1      |
+--------------+----------+------+--------+--------+

mysql_users:
+----------+-------------------+
| username | default_hostgroup |
+----------+-------------------+
| root     | 10                |
+----------+-------------------+

mysql_query_rules:
+---------+-----------------------+----------------------+
| rule_id | destination_hostgroup | match_digest         |
+---------+-----------------------+----------------------+
| 1       | 10                    | ^SELECT.*FOR UPDATE$ |
| 2       | 20                    | ^SELECT.*test1\..*   |
| 3       | 30                    | ^SELECT              |
+---------+-----------------------+----------------------+

    8. ProxySQL实现多主多从读写分离示例

    环境说明：

    IP 角色 应用 系统平台
    192.168.201.6 读写分离解析主机 proxysql rhel7.4
    192.168.201.2 master-1 mysql5.7 rhel7.4
    192.168.201.3 slave-1 mysql5.7 rhel7.4
    192.168.201.4 master-2 mysql5.7 rhel7.4
    192.168.201.5 slave-2 mysql5.7 rhel7.4

    准备工作：

    • 关闭防火墙
    • 关闭SELINUX
    • 安装mysql并配置主从

    8.1 安装ProxySQL

    //配置proxysql的yum源
//先安装mariadb
[root@proxysql ~]# cd /etc/yum.repos.d/
[root@proxysql yum.repos.d]# ls
[root@proxysql yum.repos.d]# mount /dev/cdrom /mnt
mount: /dev/sr0 写保护，将以只读方式挂载
[root@proxysql yum.repos.d]# vi xx.repo
[root@proxysql yum.repos.d]# yum -y install mariadb
[root@proxysql ~]# cat <<EOF | tee /etc/yum.repos.d/proxysql.repo			//虚拟机需要能够联通网络
> [proxysql_repo]
> name= ProxySQL
> baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/7
> gpgcheck=1
> gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key
> EOF
[proxysql_repo]
name= ProxySQL
baseurl=http://repo.proxysql.com/ProxySQL/proxysql-1.4.x/centos/7
gpgcheck=1
gpgkey=http://repo.proxysql.com/ProxySQL/repo_pub_key
[root@proxysql ~]# yum -y install proxysql

    8.2 安装mysql

    [root@master-1 ~]# yum -y install mariadb mariadb-server
[root@slave-1 ~]# yum -y install mariadb mariadb-server
[root@master-2 ~]# yum -y install mariadb mariadb-server
[root@slave-2 ~]# yum -y install mariadb mariadb-server

    8.2.1 mysql主从配置

    //配置主数据库
MASTER-1
[root@master-1 ~]# vim /etc/my.cnf
[root@master-1 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd
# mysql config
log-bin=mysql-bin
server-id=3

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

[root@master-1 ~]# systemctl start mariadb
[root@master-1 ~]# ss -antl
State      Recv-Q Send-Q                      Local Address:Port                                     Peer Address:Port
LISTEN     0      128                                     *:22                                                  *:*
LISTEN     0      100                             127.0.0.1:25                                                  *:*
LISTEN     0      50                                      *:3306                                                *:*
LISTEN     0      128                                    :::22                                                 :::*
LISTEN     0      100                                   ::1:25                                                 :::*

MASTER-2
[root@master-2 ~]# vim /etc/my.cnf
[root@master-2 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd
# mysql config
server-id=6
log-bin=mysql-bin

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

[root@master-2 ~]# systemctl start mariadb
[root@master-2 ~]# ss -antl
State      Recv-Q Send-Q                      Local Address:Port                                     Peer Address:Port
LISTEN     0      128                                     *:22                                                  *:*
LISTEN     0      100                             127.0.0.1:25                                                  *:*
LISTEN     0      50                                      *:3306                                                *:*
LISTEN     0      128                                    :::22                                                 :::*
LISTEN     0      100                                   ::1:25                                                 :::*

//配置从数据库
SLAVE-1
[root@slave-1 ~]# vim /etc/my.cnf
[root@slave-1 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd
# mysql config
server-id=5
relay-log=mysql-relay-bin

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

[root@slave-1 ~]# systemctl start mariadb
[root@slave-1 ~]# ss -antl
State      Recv-Q Send-Q                      Local Address:Port                                     Peer Address:Port
LISTEN     0      128                                     *:22                                                  *:*
LISTEN     0      100                             127.0.0.1:25                                                  *:*
LISTEN     0      50                                      *:3306                                                *:*
LISTEN     0      128                                    :::22                                                 :::*
LISTEN     0      100                                   ::1:25                                                 :::*

SLAVE-2
[root@slave-2 ~]# vim /etc/my.cnf
[root@slave-2 ~]# cat /etc/my.cnf
[mysqld]
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
# Disabling symbolic-links is recommended to prevent assorted security risks
symbolic-links=0
# Settings user and group are ignored when systemd is used.
# If you need to run mysqld under a different user or group,
# customize your systemd unit file for mariadb according to the
# instructions in http://fedoraproject.org/wiki/Systemd
# mysql config
relay-log=relay-log-mysql
server-id=8

[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid

#
# include all files from the config directory
#
!includedir /etc/my.cnf.d

[root@slave-2 ~]# systemctl start mariadb
[root@slave-2 ~]# ss -antl
State       Recv-Q Send-Q                                                  Local Address:Port                                                                 Peer Address:Port
LISTEN      0      128                                                                 *:22                                                                              *:*
LISTEN      0      100                                                         127.0.0.1:25                                                                              *:*
LISTEN      0      50                                                                  *:3306                                                                            *:*
LISTEN      0      128                                                                :::22                                                                             :::*
LISTEN      0      100                                                               ::1:25                                                                             :::*

    8.2.2 在主数据库里创建一个同步账号授权给从数据库使用

    MASTER-1
[root@master-1 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.56-MariaDB MariaDB Server

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> grant replication slave on *.* to 'zml'@'192.168.201.3' identified by 'zml123';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

//查看主库的状态
MariaDB [(none)]> show master status;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000003 |      473 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

MASTER-2
[root@master-2 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.56-MariaDB MariaDB Server

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> grant replication slave on *.* to 'zml'@'192.168.201.5' identified by 'zml123';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges
-> ;
Query OK, 0 rows affected (0.00 sec)

//查看主库的状态
MariaDB [(none)]> show master status;
+------------------+----------+--------------+------------------+
| File             | Position | Binlog_Do_DB | Binlog_Ignore_DB |
+------------------+----------+--------------+------------------+
| mysql-bin.000003 |      473 |              |                  |
+------------------+----------+--------------+------------------+
1 row in set (0.00 sec)

    8.2.3 配置并启动主从复制

    SLAVE-1
[root@slave-1 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.56-MariaDB MariaDB Server

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> change master to master_host='192.168.201.2',master_user='zml',master_password='zml123',master_log_file='mysql-bin.000003',master_log_pos=473;
Query OK, 0 rows affected (0.02 sec)

MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.201.2
Master_User: zml
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000003
Read_Master_Log_Pos: 473
Relay_Log_File: mysql-relay-bin.000002
Relay_Log_Pos: 529
Relay_Master_Log_File: mysql-bin.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 473
Relay_Log_Space: 823
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 3
1 row in set (0.00 sec)

SLAVE-2
[root@slave-2 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 2
Server version: 5.5.56-MariaDB MariaDB Server

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> change master to master_host='192.168.201.4',master_user='zml',master_password='zml123',master_log_file='mysql-bin.00
Query OK, 0 rows affected (0.05 sec)

MariaDB [(none)]> start slave;
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> show slave status \G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: 192.168.201.4
Master_User: zml
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000003
Read_Master_Log_Pos: 473
Relay_Log_File: relay-log-mysql.000002
Relay_Log_Pos: 529
Relay_Master_Log_File: mysql-bin.000003
Slave_IO_Running: Yes
Slave_SQL_Running: Yes
Replicate_Do_DB:
Replicate_Ignore_DB:
Replicate_Do_Table:
Replicate_Ignore_Table:
Replicate_Wild_Do_Table:
Replicate_Wild_Ignore_Table:
Last_Errno: 0
Last_Error:
Skip_Counter: 0
Exec_Master_Log_Pos: 473
Relay_Log_Space: 823
Until_Condition: None
Until_Log_File:
Until_Log_Pos: 0
Master_SSL_Allowed: No
Master_SSL_CA_File:
Master_SSL_CA_Path:
Master_SSL_Cert:
Master_SSL_Cipher:
Master_SSL_Key:
Seconds_Behind_Master: 0
Master_SSL_Verify_Server_Cert: No
Last_IO_Errno: 0
Last_IO_Error:
Last_SQL_Errno: 0
Last_SQL_Error:
Replicate_Ignore_Server_Ids:
Master_Server_Id: 6
1 row in set (0.00 sec)

    测试：
    在主库上创建一个数据库，然后在从库上看有没有

    MASTER-1
MariaDB [(none)]> CREATE database school;
Query OK, 1 row affected (0.00 sec)

SLAVE-1
MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| mysql              |
| performance_schema |
| school             |
| test               |
+--------------------+
5 rows in set (0.06 sec)

MASTER-2
MariaDB [(none)]> create database family;
Query OK, 1 row affected (0.01 sec)

SLAVE-2
MariaDB [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| family             |
| mysql              |
| performance_schema |
| test               |
+--------------------+
5 rows in set (0.03 sec)

    8.2.4 mysql主库添加proxysql可以增删改查的账号

    MASTER-1
[root@master-1 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 4
Server version: 5.5.56-MariaDB MariaDB Server

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> grant all on *.* to 'proxysql'@'192.168.201.6' identified by 'pwproxysql';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> exit
Bye

MASTER-2
[root@master-2 ~]# mysql
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MariaDB connection id is 4
Server version: 5.5.56-MariaDB MariaDB Server

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

MariaDB [(none)]> grant all on *.* to 'proxysql'@'192.168.201.6' identified by 'pwproxysql';
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> exit
Bye

    8.2.5 登录proxysql管理端

    [root@proxysql ~]# export MYSQL_PS1="(\u@\h:\p) [\d]> "
[root@proxysql ~]# service proxysql start
Starting ProxySQL: 2019-03-14 16:03:52 [INFO] Using config file /etc/proxysql.cnf
DONE!
[root@proxysql ~]# ss -antl
State      Recv-Q Send-Q                      Local Address:Port                                     Peer Address:Port
LISTEN     0      128                                     *:6032                                                *:*
LISTEN     0      128                                     *:6033                                                *:*
LISTEN     0      128                                     *:6033                                                *:*
LISTEN     0      128                                     *:6033                                                *:*
LISTEN     0      128                                     *:6033                                                *:*
LISTEN     0      128                                     *:22                                                  *:*
LISTEN     0      100                             127.0.0.1:25                                                  *:*
LISTEN     0      128                                    :::22                                                 :::*
LISTEN     0      100                                   ::1:25                                                 :::*
[root@proxysql ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

(admin@127.0.0.1:6032) [(none)]> show databases;
+-----+---------------+-------------------------------------+
| seq | name          | file                                |
+-----+---------------+-------------------------------------+
| 0   | main          |                                     |
| 2   | disk          | /var/lib/proxysql/proxysql.db       |
| 3   | stats         |                                     |
| 4   | monitor       |                                     |
| 5   | stats_history | /var/lib/proxysql/proxysql_stats.db |
+-----+---------------+-------------------------------------+
5 rows in set (0.00 sec)

    数据库说明：

    • main 内存配置数据库，表里存放后端db实例、用户验证、路由规则等信息。表名runtime开头的表示proxysql当前运行的配置内容，不能通过dml语句修改，只能修改对应的不以 runtime 开头的（在内存）里的表，然后 LOAD 使其生效， SAVE 使其存到硬盘以供下次重启加载
    • disk 是持久化到硬盘的配置，sqlite数据文件
    • stats 是proxysql运行抓取的统计信息，包括到后端各命令的执行次数、流量、processlist、查询种类汇总/执行时间等等
    • monitor 库存储 monitor 模块收集的信息，主要是对后端db的健康/延迟检查
    • stats_history 统计信息历史库

    8.2.6 Proxysql管理端添加后端连接mysql主从数据库的配置

    (admin@127.0.0.1:6032) [(none)]> show tables from main;
+--------------------------------------------+
| tables                                     |
+--------------------------------------------+
| global_variables                           |				# ProxySQL的基本配置参数，类似与MySQL
| mysql_collations                           |				# 配置对MySQL字符集的支持
| mysql_group_replication_hostgroups         |				# MGR相关的表，用于实例的读写组自动分配
| mysql_query_rules                          |				# 路由表
| mysql_query_rules_fast_routing             |				# 路由表
| mysql_replication_hostgroups               |				# 主从复制相关的表，用于实例的读写组自动分配
| mysql_servers                              |				# 存储MySQL实例的信息
| mysql_users                                |				# 存储MySQL用户
| proxysql_servers                           |				# 存储ProxySQL的信息，用于ProxySQL Cluster同步
| runtime_checksums_values                   |				# 运行环境的存储校验值
| runtime_global_variables                   |
| runtime_mysql_group_replication_hostgroups |
| runtime_mysql_query_rules                  |
| runtime_mysql_query_rules_fast_routing     |
| runtime_mysql_replication_hostgroups       |				# 与上面对应，但是运行环境正在使用的配置
| runtime_mysql_servers                      |
| runtime_mysql_users                        |
| runtime_proxysql_servers                   |
| runtime_scheduler                          |
| scheduler                                  |				# 定时任务表
+--------------------------------------------+
20 rows in set (0.00 sec)

    runtime_ 开头的是运行时的配置，这些是不能修改的。要修改 ProxySQL 的配置，需要修改了非 runtime_ 表，修改后必须执行 LOAD … TO RUNTIME 才能加载到 RUNTIME 生效，执行 save … to disk 才能将配置持久化保存到磁盘

    下面语句中没有先切换到 main 库也执行成功了，因为 ProxySQL 内部使用的 SQLite3 数据库引擎，和 MySQL 的解析方式是不一样的。即使执行了 USE main 语句也是无任何效果的，但不会报错
    使用 insert 语句添加 mysql 主机到 mysql_servers 表中

    //查看mysql_server表的结构
(admin@127.0.0.1:6032) [(none)]> pragma table_info("mysql_servers");
+-----+---------------------+--------------+---------+------------+----+
| cid | name                | type         | notnull | dflt_value | pk |
+-----+---------------------+--------------+---------+------------+----+
| 0   | hostgroup_id        | INT          | 1       | 0          | 1  |
| 1   | hostname            | VARCHAR      | 1       | NULL       | 2  |
| 2   | port                | INT          | 1       | 3306       | 3  |
| 3   | status              | VARCHAR      | 1       | 'ONLINE'   | 0  |
| 4   | weight              | INT          | 1       | 1          | 0  |
| 5   | compression         | INT          | 1       | 0          | 0  |
| 6   | max_connections     | INT          | 1       | 1000       | 0  |
| 7   | max_replication_lag | INT          | 1       | 0          | 0  |
| 8   | use_ssl             | INT          | 1       | 0          | 0  |
| 9   | max_latency_ms      | INT UNSIGNED | 1       | 0          | 0  |
| 10  | comment             | VARCHAR      | 1       | ''         | 0  |
+-----+---------------------+--------------+---------+------------+----+
11 rows in set (0.01 sec)

//向mysql_servers表中添加数据
(admin@127.0.0.1:6032) [(none)]> insert into mysql_servers(hostgroup_id,hostname,port,weight,comment) values(1,'192.168.201.2',3306,1,'Write ');
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> insert into mysql_servers(hostgroup_id,hostname,port,weight,comment) values(2,'192.168.201.3',3306,1,'Read ');
Query OK, 1 row affected (0.01 sec)

(admin@127.0.0.1:6032) [(none)]> insert into mysql_servers(hostgroup_id,hostname,port,weight,comment) values(1,'192.168.201.4',3306,1,'Write ');
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> insert into mysql_servers(hostgroup_id,hostname,port,weight,comment) values(2,'192.168.201.5',3306,1,'Read ');
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> select * from mysql_servers;
+--------------+---------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| hostgroup_id | hostname      | port | status | weight | compression | max_connections | max_replication_lag | use_ssl | max_latency_ms | comment |
+--------------+---------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
| 1            | 192.168.201.2 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              | Write   |
| 2            | 192.168.201.3 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              | Read    |
| 1            | 192.168.201.4 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              | Write   |
| 2            | 192.168.201.5 | 3306 | ONLINE | 1      | 0           | 1000            | 0                   | 0       | 0              | Read    |
+--------------+---------------+------+--------+--------+-------------+-----------------+---------------------+---------+----------------+---------+
4 rows in set (0.00 sec)

    修改后，需要加载到RUNTIME，并保存到disk

    (admin@127.0.0.1:6032) [(none)]> load mysql servers to runtime;
Query OK, 0 rows affected (0.01 sec)

(admin@127.0.0.1:6032) [(none)]> save mysql servers to disk;
Query OK, 0 rows affected (0.04 sec)

    在 proxysql 主机的 mysql_users 表中添加刚才在 master 上创建的账号 proxysql，proxysql 客户端需要使用这个账号来访问数据库
    default_hostgroup 默认组设置为写组，也就是1;
    当读写分离的路由规则不符合时，会访问默认组的数据库;

    (admin@127.0.0.1:6032) [(none)]> show tables from main;
+--------------------------------------------+
| tables                                     |
+--------------------------------------------+
| global_variables                           |
| mysql_collations                           |
| mysql_group_replication_hostgroups         |
| mysql_query_rules                          |
| mysql_query_rules_fast_routing             |
| mysql_replication_hostgroups               |
| mysql_servers                              |
| mysql_users                                |
| proxysql_servers                           |
| runtime_checksums_values                   |
| runtime_global_variables                   |
| runtime_mysql_group_replication_hostgroups |
| runtime_mysql_query_rules                  |
| runtime_mysql_query_rules_fast_routing     |
| runtime_mysql_replication_hostgroups       |
| runtime_mysql_servers                      |
| runtime_mysql_users                        |
| runtime_proxysql_servers                   |
| runtime_scheduler                          |
| scheduler                                  |
+--------------------------------------------+
20 rows in set (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> pragma table_info("mysql_users");
+-----+------------------------+---------+---------+------------+----+
| cid | name                   | type    | notnull | dflt_value | pk |
+-----+------------------------+---------+---------+------------+----+
| 0   | username               | VARCHAR | 1       | NULL       | 1  |
| 1   | password               | VARCHAR | 0       | NULL       | 0  |
| 2   | active                 | INT     | 1       | 1          | 0  |
| 3   | use_ssl                | INT     | 1       | 0          | 0  |
| 4   | default_hostgroup      | INT     | 1       | 0          | 0  |
| 5   | default_schema         | VARCHAR | 0       | NULL       | 0  |
| 6   | schema_locked          | INT     | 1       | 0          | 0  |
| 7   | transaction_persistent | INT     | 1       | 1          | 0  |
| 8   | fast_forward           | INT     | 1       | 0          | 0  |
| 9   | backend                | INT     | 1       | 1          | 2  |
| 10  | frontend               | INT     | 1       | 1          | 0  |
| 11  | max_connections        | INT     | 1       | 10000      | 0  |
+-----+------------------------+---------+---------+------------+----+
12 rows in set (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> insert into mysql_users(username,password,default_hostgroup,transaction_persistent) values('proxysql','pwproxysql',1,1);
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> select * from mysql_users \G
*************************** 1. row ***************************
username: proxysql				# 后端mysql实例的用户名
password: pwproxysql				# 后端mysql实例的密码
active: 1				# active=1表示用户生效，0表示不生效
use_ssl: 0
default_hostgroup: 1				# 用户默认登录到哪个hostgroup_id下的实例
default_schema: NULL				# 用户默认登录后端mysql实例时连接的数据库，这个地方为NULL的话，则由全局变量mysql-default_schema决定，默认是information_schema
schema_locked: 0
transaction_persistent: 1				# 如果设置为1，连接上ProxySQL的会话后，如果在一个hostgroup上开启了事务，那么后续的sql都继续维持在这个hostgroup上，不论是否会匹配上其它路由规则，直到事务结束。虽然默认是0
fast_forward: 0				# 忽略查询重写/缓存层，直接把这个用户的请求透传到后端DB。相当于只用它的连接池功能，一般不用，路由规则 .* 就行了
backend: 1
backend: 1
frontend: 1
max_connections: 10000				# 该用户允许的最大连接数
1 row in set (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> load mysql users to runtime;
Query OK, 0 rows affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> save mysql users to disk;
Query OK, 0 rows affected (0.03 sec)

    8.2.7 添加健康检测的帐号

    在mysql的 master 端添加属于proxysql的只读账号

    MASTER-1
MariaDB [(none)]> GRANT SELECT ON *.* TO 'monitor'@'%' IDENTIFIED BY 'monitor';
Query OK, 0 rows affected (0.01 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

MASTER-2
MariaDB [(none)]> GRANT SELECT ON *.* TO 'monitor'@'%' IDENTIFIED BY 'monitor';
Query OK, 0 rows affected (0.00 sec)

MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.00 sec)

    在proxysql主机端修改变量设置健康检测的账号

    (admin@127.0.0.1:6032) [(none)]> set mysql-monitor_username='monitor';
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> set mysql-monitor_password='monitor';
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> load mysql variables to runtime;
Query OK, 0 rows affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> save mysql variables to disk;
Query OK, 97 rows affected (0.02 sec)

    8.2.8 添加读写分离的路由规则

    需求：

    • 将 select 查询语句全部路由至 hostgroup_id=2 的组(也就是读组)
    • 但是 select * from tb for update 这样的语句是会修改数据的，所以需要单独定义，将它路由至 hostgroup_id=1 的组(也就是写组)
    • 其他没有被规则匹配到的组将会被路由至用户默认的组(mysql_users 表中的 default_hostgroup)
    (admin@127.0.0.1:6032) [(none)]> insert into mysql_query_rules(rule_id,active,match_digest,destination_hostgroup,apply)values(1,1,'^SELECT.*FOR UPDATE$',1,1);
Query OK, 1 row affected (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> insert into mysql_query_rules(rule_id,active,match_digest,destination_hostgroup,apply)values(2,1,'^SELECT',2,1);
Query OK, 1 row affected (0.01 sec)

(admin@127.0.0.1:6032) [(none)]> select rule_id,active,match_digest,destination_hostgroup,apply from mysql_query_rules;
+---------+--------+----------------------+-----------------------+-------+
| rule_id | active | match_digest         | destination_hostgroup | apply |
+---------+--------+----------------------+-----------------------+-------+
| 1       | 1      | ^SELECT.*FOR UPDATE$ | 1                     | 1     |
| 2       | 1      | ^SELECT              | 2                     | 1     |
+---------+--------+----------------------+-----------------------+-------+
2 rows in set (0.00 sec)

(admin@127.0.0.1:6032) [(none)]> load mysql query rules to runtime;
Query OK, 0 rows affected (0.01 sec)

(admin@127.0.0.1:6032) [(none)]> save mysql query rules to disk;
Query OK, 0 rows affected (0.03 sec)

    8.3 验证读写分离

    8.3.1 登录 proxysql 客户端

    登录用户是刚才我们在 mysql_user 表中创建的用户，端口为6033

    [root@proxysql ~]# mysql -uproxysql -ppwproxysql -h127.0.0.1 -P6033
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 14
Server version: 5.5.30 (ProxySQL)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

(proxysql@127.0.0.1:6033) [(none)]> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| family             |
| mysql              |
| performance_schema |
| test               |
+--------------------+
5 rows in set (0.01 sec)

    8.3.2 尝试修改数据库和查询

    创建1个数据库并查询一下表

    [root@proxysql ~]# mysql -uproxysql -ppwproxysql -h127.0.0.1 -P6033
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 17
Server version: 5.5.30 (ProxySQL)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

(proxysql@127.0.0.1:6033) [(none)]> create database kk;
Query OK, 1 row affected (0.00 sec)

(proxysql@127.0.0.1:6033) [(none)]> select user,host from mysql.user;
+----------+---------------+
| user     | host          |
+----------+---------------+
| monitor  | %             |
| root     | 127.0.0.1     |
| zml      | 192.168.201.2 |
| proxysql | 192.168.201.6 |
| root     | ::1           |
|          | localhost     |
| root     | localhost     |
|          | slave-2       |
| root     | slave-2       |
+----------+---------------+
9 rows in set (0.01 sec)

    8.3.3 验证读写分离是否成功

    proxysql有个类似审计的功能，可以查看各类SQL的执行情况，其需要在proxysql管理端执行

    [root@proxysql ~]# mysql -uadmin -padmin -h127.0.0.1 -P6032
Welcome to the MariaDB monitor.  Commands end with ; or \g.
Your MySQL connection id is 19
Server version: 5.5.30 (ProxySQL Admin Module)

Copyright (c) 2000, 2017, Oracle, MariaDB Corporation Ab and others.

Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.

(admin@127.0.0.1:6032) [(none)]> select * from stats_mysql_query_digest \G
*************************** 1. row ***************************
hostgroup: 2
schemaname: information_schema
username: proxysql
digest: 0x620B328FE9D6D71A
digest_text: SELECT DATABASE()
count_star: 1
first_seen: 1552556852
last_seen: 1552556852
sum_time: 77876
min_time: 77876
max_time: 77876
*************************** 2. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0xC6089B623A8762ED
digest_text: drop database kk
count_star: 2
first_seen: 1552556808
last_seen: 1552556852
sum_time: 12067
min_time: 4749
max_time: 7318
*************************** 3. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0x4197116F34541B76
digest_text: delete kk
count_star: 1
first_seen: 1552556669
last_seen: 1552556669
sum_time: 1273
min_time: 1273
max_time: 1273
*************************** 4. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0xF505F085607AA57D
digest_text: delete database kk
count_star: 1
first_seen: 1552556663
last_seen: 1552556663
sum_time: 2888
min_time: 2888
max_time: 2888
*************************** 5. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0x3224D92906609453
digest_text: delete from mysql_users where username = ?
count_star: 1
first_seen: 1552556054
last_seen: 1552556054
sum_time: 3172
min_time: 3172
max_time: 3172
*************************** 6. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0xAA413EEF50CDDE32
digest_text: create database kk
count_star: 4
first_seen: 1552554511
last_seen: 1552557126
sum_time: 16444
min_time: 2471
max_time: 6828
*************************** 7. row ***************************
hostgroup: 2
schemaname: information_schema
username: proxysql
digest: 0x0F02B330C823D739
digest_text: select user,host from mysql.user
count_star: 2
first_seen: 1552554548
last_seen: 1552557156
sum_time: 16052
min_time: 7916
max_time: 8136
*************************** 8. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0x02033E45904D3DF0
digest_text: show databases
count_star: 10
first_seen: 1552554433
last_seen: 1552557080
sum_time: 39276
min_time: 2026
max_time: 9461
*************************** 9. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0x594F2C744B698066
digest_text: select USER()
count_star: 8
first_seen: 1552554422
last_seen: 1552557118
sum_time: 0
min_time: 0
max_time: 0
*************************** 10. row ***************************
hostgroup: 1
schemaname: information_schema
username: proxysql
digest: 0x226CD90D52A2BA0B
digest_text: select @@version_comment limit ?
count_star: 8
first_seen: 1552554422
last_seen: 1552557118
sum_time: 0
min_time: 0
max_time: 0
10 rows in set (0.00 sec)
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