1+X 云计算运维与开发（中级）案例实战——使用 Mycat 构建读写分离的数据库集群
1+X 云计算运维与开发（中级）案例实战——使用 Mycat 服务构建读写分离的数据库集群
- 前言
- 思路
- 实操
-
- 1.修改主机名，修改主机映射，配置yum源
- 2.给mycat机安装java服务，给db1和db2安装mysql
- 3.给db1和db2部署主从数据库集群
-
- 3.1启动mysql服务，并初始化（两台）
- 3.2 配置db1
-
- 3.2.1 编辑主节点 db1 虚拟机的数据库配置文件 my.cnf
- 3.2.2 开放主节点的数据库权限
- 3.3 配置db2
-
- 3.3.1配置从节点 db2 同步主节点 db1
- 3.4 验证主从数据库的同步功能
- 4.在mycat机部署 Mycat 数据库中间件服务
- 总结
前言
学而不思则罔，思而不学则殆。
| IP | 主机名 | 节点 |
|---|---|---|
| 192.168.200.10 | mycat | Mycat中间件服务节点 |
| 192.168.200.20 | db1 | MariaDB 数据库集群主节点 |
| 192.168.200.30 | db2 | MariaDB 数据库集群从节点 |
思路
1.修改主机名，配置yum源;
2.给mycat机安装java服务，给db1和db2安装mysql;
3.给db1和db2部署主从数据库集群；
4.在mycat机部署 Mycat 数据库中间件服务
实操
1.修改主机名，修改主机映射，配置yum源
代码如下：
Mycat：
[root@xnode1 ~]# hostnamectl set-hostname mycat
[root@xnode1 ~]# bash
[root@mycat ~]#
db1：
[root@xnode1 ~]# hostnamectl set-hostname db1
[root@xnode1 ~]# bash
[root@db1 ~]#
db2：
[root@xnode1 ~]# hostnamectl set-hostname db1
[root@xnode1 ~]# bash
[root@db2 ~]#
在 /etc/hosts文件中添加以下内容：
192.168.200.10 mycat
192.168.200.20 db1
192.168.200.30 db2
配置yum源（ftp)
注意：需要自行准备gpmall-repo文件
mycat:
[root@mycat ~]# rm -rf /etc/yum.repos.d/*
[root@mycat ~]# mv gpmall-repo /opt
[root@mycat ~]# mkdir /opt/cdrom ; mount CentOS-7-x86_64-DVD-1511.iso /opt/cdrom
mount: /dev/loop0 is write-protected, mounting read-only
[root@mycat ~]# cat /etc/yum.repos.d/local.repo
[centos]
name=centos
baseurl=file:///opt/cdrom
gpgcheck=0
[gpmall]
name=gpmall
baseurl=file:///opt/gpmall-repo
gpgcheck=0
[root@mycat ~]# yum repolist
Loaded plugins: fastestmirror
centos | 3.6 kB 00:00:00
(1/2): centos/group_gz | 155 kB 00:00:00
(2/2): centos/primary_db | 2.8 MB 00:00:00
Determining fastest mirrors
repo id repo name status
centos centos 3,723
gpmall gpmall 165
repolist: 3,888
db1:
[root@db1 ~]# rm -rf /etc/yum.repos.d/*
[root@db1 ~]# cat /etc/yum.repos.d/local.repo
[centos]
name=centos
baseurl=ftp://192.168.200.10/cdrom
gpgcheck=0
[gpmall]
name=gpmall
baseurl=ftp://192.168.200.10/gpmall-repo
gpgcheck=0
db2:
[root@db1 ~]# rm -rf /etc/yum.repos.d/*
[root@db2 ~]# cat /etc/yum.repos.d/local.repo
[centos]
name=centos
baseurl=ftp://192.168.200.10/cdrom
gpgcheck=0
[gpmall]
name=gpmall
baseurl=ftp://192.168.200.10/gpmall-repo
gpgcheck=0
在mycat机上安装ftp，并设置共享文件路径：
[root@mycat ~]# yum -y install vsftpd
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
Resolving Dependencies
--> Running transaction check
---> Package vsftpd.x86_64 0:3.0.2-10.el7 will be installed
--> Finished Dependency Resolution
Dependencies Resolved
=======================================================================================================
Package Arch Version Repository Size
=======================================================================================================
Installing:
vsftpd x86_64 3.0.2-10.el7 centos 167 k
Transaction Summary
=======================================================================================================
Install 1 Package
Total download size: 167 k
Installed size: 347 k
Downloading packages:
Running transaction check
Running transaction test
Transaction test succeeded
Running transaction
Installing : vsftpd-3.0.2-10.el7.x86_64 1/1
Verifying : vsftpd-3.0.2-10.el7.x86_64 1/1
Installed:
vsftpd.x86_64 0:3.0.2-10.el7
Complete!
[root@mycat ~]# vi /etc/vsftpd/vsftpd.conf
anon_root=/opt ##这一行在配置文件的第一行添加就行
···
[root@mycat ~]# systemctl restart vsftpd
最好把gpmall-repo放到 /opt目录下，这样就不用做过多的操作
注意：关闭防火墙，否则会报错
[root@db1 ~]# yum repolist
Loaded plugins: fastestmirror
ftp://192.168.200.10/cdrom/repodata/repomd.xml: [Errno 14] curl#7 - "Failed connect to 192.168.200.10:21; No route to host"
Trying other mirror.
ftp://192.168.200.10/cdrom/repodata/repomd.xml: [Errno 14] curl#7 - "Failed connect to 192.168.200.10:21; No route to host"
Trying other mirror.
ftp://192.168.200.10/cdrom/repodata/repomd.xml: [Errno 14] curl#7 - "Failed connect to 192.168.200.10:21; No route to host"
Trying other mirror.
ftp://192.168.200.10/cdrom/repodata/repomd.xml: [Errno 14] curl#7 - "Failed connect to 192.168.200.10:21; No route to host"
Trying other mirror.
---
关闭防火墙(三台机子都要做）：
[root@mycat ~]# systemctl stop firewalld
[root@mycat ~]# setenforce 0
成功结果：
mycat:
[root@mycat ~]# yum repolist
Loaded plugins: fastestmirror
Loading mirror speeds from cached hostfile
repo id repo name status
centos centos 3,723
gpmall gpmall 165
repolist: 3,888
db1:
[root@db1 ~]# yum repolist
Loaded plugins: fastestmirror
centos | 3.6 kB 00:00:00
gpmall | 2.9 kB 00:00:00
(1/2): centos/group_gz | 155 kB 00:00:00
(2/2): gpmall/primary_db | 144 kB 00:00:00
Determining fastest mirrors
repo id repo name status
centos centos 3,723
gpmall gpmall 165
repolist: 3,888
db2:
[root@db2 ~]# yum repolist
Loaded plugins: fastestmirror
centos | 3.6 kB 00:00:00
gpmall | 2.9 kB 00:00:00
(1/2): centos/group_gz | 155 kB 00:00:00
(2/2): gpmall/primary_db | 144 kB 00:00:00
Determining fastest mirrors
repo id repo name status
centos centos 3,723
gpmall gpmall 165
repolist: 3,888
2.给mycat机安装java服务，给db1和db2安装mysql
mycat:
[root@mycat ~]# yum -y install java-1.8.0-openjdk java-1.8.0-openjdk-devel
db1:
[root@db1 ~]# yum -y install mariadb mariadb-server
db2:
[root@db2 ~]# yum -y install mariadb mariadb-server
3.给db1和db2部署主从数据库集群
3.1启动mysql服务，并初始化（两台）
这里以db1为例，db2相同操作：
[root@db1 ~]# mysql_secure_installation
Set root password? [Y/n] #直接回车
New password: #密码必须为123456，因为脚本文件里配置的
Re-enter new password: #再输入一次123456
Password updated successfully!
Reloading privilege tables..
... Success!
Remove anonymous users? [Y/n] #输入y或者直接回车
... Success!
Normally, root should only be allowed to connect from 'localhost'. This
ensures that someone cannot guess at the root password from the network.
Disallow root login remotely? [Y/n] #输入n
... skipping.
Remove test database and access to it? [Y/n] #输入y或者直接回车
- Dropping test database...
... Success!
- Removing privileges on test database...
... Success!
Reload privilege tables now? [Y/n] #输入y或者直接回车
... Success!
3.2 配置db1
3.2.1 编辑主节点 db1 虚拟机的数据库配置文件 my.cnf
在配置文件 my.cnf 中增添下面的内容：
[root@db1 ~]# vi /etc/my.cnf
[mysqld]
log-bin = mysql-bin #记录操作日志
binlog-ignore-db = mysql #不同步 MySQL 系统数据库
server-id = 20
#数据库集群中的每个节点 id 都要不同，一般使用 IP 地址的最后段的数字
#例如 172.16.51.18，server_id 就写 18
datadir=/var/lib/mysql
socket=/var/lib/mysql/mysql.sock
symbolic-links = 0
[mysqld_safe]
log-error=/var/log/mariadb/mariadb.log
pid-file=/var/run/mariadb/mariadb.pid
重启很重要：
[root@db1 ~]# systemctl restart mariadb
## 重启mariadb
my.cnf文件详解看——转载自：http://t.csdn.cn/srCVq
3.2.2 开放主节点的数据库权限
[root@db1 ~]# mysql -uroot -p123456
在主节点 db1 虚拟机上使用 mysql 命令登录 MariaDB 数据库授权在任何客户端机器上可以以 root 用户登录到数据库。
MariaDB [(none)]> grant all privileges on *.* to root@'%' identified by '123456';
Query OK, 0 rows affected (0.000 sec)
在主节点 db1 数据库上创建一个 user 用户让从节点 db2 连接并赋予从节点同步主节点数据库的权限
MariaDB [(none)]> grant replication slave on *.* to 'user'@'db2' identified by '123456';
Query OK, 0 rows affected (0.000 sec)
刷新权限很重要：
MariaDB [(none)]> flush privileges;
Query OK, 0 rows affected (0.000 sec)
3.3 配置db2
3.3.1配置从节点 db2 同步主节点 db1
在从节点 db2 虚拟机上使用 mysql 命令登录 MariaDB 数据库，配置从节点连接主节点的连接信息。master_host 为主节点主机名 db1，master_user 为在步骤3.3.2中创建的用户 user
[root@db2 ~]# mysql -uroot -p123456
MariaDB [(none)]> change master to master_host='db1',master_user='user',master_password='123456';
配置完毕主从数据库之间的连接信息之后，开启从节点服务。使用 show slave status\G;命令并查看从节点服务状态，如果Slave_IO_Running 和 Slave_SQL_Running 的状态都为 YES，则从节点服务开启成功。
MariaDB [(none)]> start slave;
MariaDB [(none)]> show slave status\G
*************************** 1. row ***************************
Slave_IO_State: Waiting for master to send event
Master_Host: db1
Master_User: user
Master_Port: 3306
Connect_Retry: 60
Master_Log_File: mysql-bin.000001
Read_Master_Log_Pos: 1133
Relay_Log_File: db2-relay-bin.000002
Relay_Log_Pos: 1432
Relay_Master_Log_File: mysql-bin.000001
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: 1133
Relay_Log_Space: 1739
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: 20
Master_SSL_Crl:
Master_SSL_Crlpath:
Using_Gtid: No
Gtid_IO_Pos:
Replicate_Do_Domain_Ids:
Replicate_Ignore_Domain_Ids:
Parallel_Mode: conservative
SQL_Delay: 0
SQL_Remaining_Delay: NULL
Slave_SQL_Running_State: Slave has read all relay log; waiting for the slave I/O thread to update it
Slave_DDL_Groups: 5
Slave_Non_Transactional_Groups: 0
Slave_Transactional_Groups: 0
1 row in set (0.000 sec)
这里之前可能忘记把db1和db2的防火墙关闭了，所以报了个错(本篇文章暂不展示）
具体可以看https://blog.csdn.net/famudd/article/details/123690498
3.4 验证主从数据库的同步功能
先在主节点 db1 的数据库中创建库 test，并在库 test 中创建表company，插入表数据。创建完成后，查看表 company 数据
[root@db1 ~]# mysql -uroot -p123456
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 167
Server version: 10.3.18-MariaDB-log MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> create database test;
Query OK, 1 row affected (0.000 sec)
MariaDB [(none)]> use test
Database changed
MariaDB [test]> create table company(id int not null primary key,name varchar(50),addr varchar(255));
Query OK, 0 rows affected (0.002 sec)
MariaDB [test]> insert into company values(1,"facebook","usa");
Query OK, 1 row affected (0.001 sec)
MariaDB [test]> select * from company;
+----+----------+------+
| id | name | addr |
+----+----------+------+
| 1 | facebook | usa |
+----+----------+------+
1 row in set (0.000 sec)
这时从节点 db2 的数据库就会同步主节点数据库创建的 test 库,可以在从节点查询 test数据库与表 company，如果可以查询到信息，就能验证主从数据库集群功能在正常运行
[root@db2 ~]# mysql -uroot -p123456
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MariaDB connection id is 167
Server version: 10.3.18-MariaDB-log MariaDB Server
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MariaDB [(none)]> show databases;
+--------------------+
| Database |
+--------------------+
| information_schema |
| mysql |
| performance_schema |
| test |
+--------------------+
4 rows in set (0.000 sec)
MariaDB [(none)]> select * from test.company;
+----+----------+------+
| id | name | addr |
+----+----------+------+
| 1 | facebook | usa |
+----+----------+------+
1 row in set (0.000 sec)
4.在mycat机部署 Mycat 数据库中间件服务
上传并解压 Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz ，解压到 /usr/local/
[root@mycat ~]# tar -zxvf Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz -C /usr/local/
给解压出来的 **/mycat/**赋权限
[root@mycat ~]# chmod -R 777 /usr/local/mycat/
在/etc/profile 系统变量文件中添加 Mycat 服务的系统变量，并生效变量
[root@mycat ~]# echo export MYCAT_HOME=/usr/local/mycat >> /etc/profile
[root@mycat ~]# source /etc/profile
编辑 Mycat 的逻辑库配置文件 schema.xml
[root@mycat ~]# vi /usr/local/mycat/conf/schema.xml
##原文件展示
[root@mycat ~]# vi /usr/local/mycat/conf/schema.xml
<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/">
<schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100">
<!-- auto sharding by id (long) -->
<table name="travelrecord" dataNode="dn1,dn2,dn3" rule="auto-sharding-long" />
<!-- global table is auto cloned to all defined data nodes ,so can join
with any table whose sharding node is in the same data node -->
<table name="company" primaryKey="ID" type="global" dataNode="dn1,dn2,dn3" />
<table name="goods" primaryKey="ID" type="global" dataNode="dn1,dn2" />
<!-- random sharding using mod sharind rule -->
<table name="hotnews" primaryKey="ID" autoIncrement="true" dataNode="dn1,dn2,dn3"
rule="mod-long" />
<!-- <table name="dual" primaryKey="ID" dataNode="dnx,dnoracle2" type="global"
needAddLimit="false"/> <table name="worker" primaryKey="ID" dataNode="jdbc_dn1,jdbc_dn2,jdbc_dn3"
rule="mod-long" /> -->
<table name="employee" primaryKey="ID" dataNode="dn1,dn2"
rule="sharding-by-intfile" />
<table name="customer" primaryKey="ID" dataNode="dn1,dn2"
rule="sharding-by-intfile">
<childTable name="orders" primaryKey="ID" joinKey="customer_id"
parentKey="id">
<childTable name="order_items" joinKey="order_id"
parentKey="id" />
</childTable>
<childTable name="customer_addr" primaryKey="ID" joinKey="customer_id"
parentKey="id" />
</table>
<!-- <table name="oc_call" primaryKey="ID" dataNode="dn1$0-743" rule="latest-month-calldate"
/> -->
</schema>
<!-- <dataNode name="dn1$0-743" dataHost="localhost1" database="db$0-743"
/> -->
<dataNode name="dn1" dataHost="localhost1" database="db1" />
<dataNode name="dn2" dataHost="localhost1" database="db2" />
<dataNode name="dn3" dataHost="localhost1" database="db3" />
<!--<dataNode name="dn4" dataHost="sequoiadb1" database="SAMPLE" />
<dataNode name="jdbc_dn1" dataHost="jdbchost" database="db1" />
<dataNode name="jdbc_dn2" dataHost="jdbchost" database="db2" />
<dataNode name="jdbc_dn3" dataHost="jdbchost" database="db3" /> -->
<dataHost name="localhost1" maxCon="1000" minCon="10" balance="0"
writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100">
<heartbeat>select user()</heartbeat>
<!-- can have multi write hosts -->
<writeHost host="hostM1" url="localhost:3306" user="root"
password="123456">
<!-- can have multi read hosts -->
<readHost host="hostS2" url="192.168.1.200:3306" user="root" password="xxx" />
</writeHost>
<writeHost host="hostS1" url="localhost:3316" user="root"
password="123456" />
<!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> -->
</dataHost>
<!--
<dataHost name="sequoiadb1" maxCon="1000" minCon="1" balance="0" dbType="sequoiadb" dbDriver="jdbc">
<heartbeat> </heartbeat>
<writeHost host="hostM1" url="sequoiadb://1426587161.dbaas.sequoialab.net:11920/SAMPLE" user="jifeng" password="jifeng"></writeHost>
</dataHost>
<dataHost name="oracle1" maxCon="1000" minCon="1" balance="0" writeType="0" dbType="oracle" dbDriver="jdbc"> <heartbeat>select 1 from dual</heartbeat>
<connectionInitSql>alter session set nls_date_format='yyyy-mm-dd hh24:mi:ss'</connectionInitSql>
<writeHost host="hostM1" url="jdbc:oracle:thin:@127.0.0.1:1521:nange" user="base" password="123456" > </writeHost> </dataHost>
<dataHost name="jdbchost" maxCon="1000" minCon="1" balance="0" writeType="0" dbType="mongodb" dbDriver="jdbc">
<heartbeat>select user()</heartbeat>
<writeHost host="hostM" url="mongodb://192.168.0.99/test" user="admin" password="123456" ></writeHost> </dataHost>
<dataHost name="sparksql" maxCon="1000" minCon="1" balance="0" dbType="spark" dbDriver="jdbc">
<heartbeat> </heartbeat>
<writeHost host="hostM1" url="jdbc:hive2://feng01:10000" user="jifeng" password="jifeng"></writeHost> </dataHost> -->
<!-- <dataHost name="jdbchost" maxCon="1000" minCon="10" balance="0" dbType="mysql"
dbDriver="jdbc"> <heartbeat>select user()</heartbeat> <writeHost host="hostM1"
url="jdbc:mysql://localhost:3306" user="root" password="123456"> </writeHost>
</dataHost> -->
</mycat:schema>
正确更改完的样子：
1 <?xml version="1.0"?>
2 <!DOCTYPE mycat:schema SYSTEM "schema.dtd">
3 <mycat:schema xmlns:mycat="http://io.mycat/">
4
5 <schema name="USERDB" checkSQLschema="true" sqlMaxLimit="100" dataNode='dn1'>
6 </schema>
7 <dataNode name="dn1" dataHost="localhost1" database="test" />
8 <dataHost name="localhost1" maxCon="1000" minCon="10" balance="3"
9 writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveT hreshold="100">
10 <heartbeat>select user()</heartbeat>
11 <!-- can have multi write hosts -->
12 <writeHost host="hostM1" url="192.168.200.20:3306" user="root"
13 password="123456">
14 <!-- can have multi read hosts -->
15 <readHost host="hostS1" url="192.168.200.30:3306" user="root" password= "123456" />
16 </writeHost>
17 </dataHost>
18 </mycat:schema>
这里我总结一下我的修改思路
1.修改第5行的TESTDB"为 USERDB； false改为 true；
在’ >'前面添加 dataNode=‘dn1’.
2.将光标移到第6行，进入 vi编辑器的命令行模式，输入 27dd，意思是删除（事实上是剪切）从这行开始到下面的27行，dd必须小写。
3.在第2步的基础上将光标移到第7行，使用dd（不需要输入数字）两次，也就是删除第7行和第8行。
4.在第3步的基础上编辑第7行的 db1，将其改为 test
5.将光标放到第8行，进入到命令行模式，输入 6dd。
6.在第5步的基础上，修改第8行的 balance，将它的值从0改为3
7.将光标移到第12行，将localhost改为db1的IP地址，这行认准hostM1
8.将光标移到第15行，将hostS2改为hostS1；将url的值改为：db2的IP地址：3306；将password的值改为123456
9.将光标移到第17行，进入命令行模式，输入3dd
10.在第9步的基础上，将光标移到第18行，命令行模式，输入22dd
该文件的详解转载：https://blog.csdn.net/weixin_42098207/article/details/105454315
修改 schema.xml 的用户权限
[root@mycat ~]# chown root:root /usr/local/mycat/conf/server.xml
修改/usr/local/mycat/conf/目录下的 server.xml 文件，修改 root用户的访问密码与数据库，密码设置为 123456，访问 Mycat 的逻辑库为 USERDB
修改部分：
80 <user name="root">
81 <property name="password">123456</property>
82 <property name="schemas">USERDB</property>
删除部分：
95 <user name="user">
96 <property name="password">user</property>
97 <property name="schemas">TESTDB</property>
98 <property name="readOnly">true</property>
99 </user>
启动Mycat服务:
[root@mycat ~]# /bin/bash /usr/local/mycat/bin/mycat start
Starting Mycat-server...
[root@mycat ~]# jps
4162 Jps
4126 WrapperSimpleApp
安装net-tools，使用netstat -ntpl | grep 8066 or 9066 来查看服务端口
[root@mycat ~]# yum -y install net-tools
[root@mycat ~]# netstat -ntpl | grep 9066
tcp6 0 0 :::9066 :::* LISTEN 4126/java
[root@mycat ~]# netstat -ntpl | grep 8066
tcp6 0 0 :::8066 :::* LISTEN 4126/java
安装mariadb-client服务
[root@mycat ~]# yum -y install MariaDB-client
在 Mycat 虚拟机上使用 mysql 命令查看 Mycat 服务的逻辑库USERDB，因为 Mycat 的逻辑库 USERDB 对应数据库 test（在部署主从数据库时已安装），所以可以查看库中已经创建的表 company
[root@mycat ~]# mysql -h127.0.0.1 -P8066 -uroot -p123456
Welcome to the MariaDB monitor. Commands end with ; or \g.
Your MySQL connection id is 1
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)
Copyright (c) 2000, 2018, Oracle, MariaDB Corporation Ab and others.
Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.
MySQL [(none)]> show databases;
+----------+
| DATABASE |
+----------+
| USERDB |
+----------+
1 row in set (0.001 sec)
MySQL [(none)]> use USERDB
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 [USERDB]> show table company ;
ERROR 1064 (42000): You have an error in your SQL syntax; check the manual that corresponds to your MariaDB server version for the right syntax to use near 'company' at line 1
MySQL [USERDB]> show tables;
+----------------+
| Tables_in_test |
+----------------+
| company |
+----------------+
1 row in set (0.001 sec)
MySQL [USERDB]> select * from company ;
+----+----------+------+
| id | name | addr |
+----+----------+------+
| 1 | facebook | usa |
+----+----------+------+
1 row in set (0.026 sec)
MySQL [USERDB]> insert into company values(2,"abook","aus");
Query OK, 1 row affected (0.004 sec)
MySQL [USERDB]> select * from company ;
+----+----------+------+
| id | name | addr |
+----+----------+------+
| 1 | facebook | usa |
| 2 | abook | aus |
+----+----------+------+
2 rows in set (0.001 sec)
在 Mycat 虚拟机节点使用 mysql 命令，通过 9066 端口查询对数据库读写操作的分离信息。可以看到所有的写入操作WRITE_LOAD 数都在 db1 主数据库节点上，所有的读取操作READ_LOAD 数都在 db2 主数据库节点上
[root@mycat ~]# mysql -h127.0.0.1 -P9066 -uroot -p123456 -e 'show @@datasource;'
+----------+--------+-------+----------------+------+------+--------+------+------+---------+-----------+------------+
| DATANODE | NAME | TYPE | HOST | PORT | W/R | ACTIVE | IDLE | SIZE | EXECUTE | READ_LOAD | WRITE_LOAD |
+----------+--------+-------+----------------+------+------+--------+------+------+---------+-----------+------------+
| dn1 | hostM1 | mysql | 192.168.200.20 | 3306 | W | 0 | 6 | 1000 | 71 | 0 | 1 |
| dn1 | hostS1 | mysql | 192.168.200.30 | 3306 | R | 0 | 6 | 1000 | 65 | 5 | 0 |
+----------+--------+-------+----------------+------+------+--------+------+------+---------+-----------+------------+
说明：
我尝试过在主数据库部署了一个单节点应用商城系统
然后使用浏览器打开商城，访问了很多商品信息
最后得到的结果是：
EXECUTE 的值会随着访问商品信息的次数变化而变大；而 READ_LOAD 不会
经过和老师的探讨，暂时确定 READ_LOAD 表示的是客户端与数据库建立连接的次数，而非我们读取数据库中的数据的次数 ！！！
总结
咬定青山不放松，立根原在破岩中。
千磨万击还坚劲，任尔东西南北风。
----郑燮《竹石》