mycat实验之主从配置读写分离和分表

1.实验环境：

vmware虚机3个   （虚机太少了，电脑有点吃力，3个虚机只能达到基本的测试）

系统centos7     （实验是关闭防火墙和selinux做的）

mysql版本5.7

mycat版本1.6

虚机名字和ip：

mysql1 192.168.211.138

mysql2 192.168.211.139

mysql3 192.168.211.142

mycat安装在mysql1(192.168.211.138)

这台主机须能够解析mysql2,mysql3的地址。

可通过/etc/hosts  手动添加解析

2.实验目的

实现mycat读写分离和分表的功能。

3.实验思路

在mycat创建一个逻辑库：hello。

创建四个表格：

t1   这个表格用来分片，用枚举的规则分片。

t2   这个表格做全局表。

t3   这个表格做普通表，定义它放到其中一个datanode,放到mysql1

t4   这个表格做普通表，定义它放到其中一个datanode,放到mysql3

虚机的分配：

mysql1 和mysql2做主从配置，其中mysql1为主，mysql2为从,其中mysql1用来写，mysql2用来读。

mysql3 就是个单独的datanode

实际我们只有两个datanode，mysql1,mysql3。

4.实验步骤

分别在虚机安装mysql5.7，步骤略。

设置mysql用户，步骤略。请注意，必须设置一个用户允许内网地址连接或者干脆是允许任何地方连接。比如设置'root'@'%'。

安装mycat。步骤略。

配置mysql1和mysql2主从，步骤略。

以上都是些常用配置，懒得特意记录了。

以上的环境都配置好了，就可以开始我们实验核心步骤mycat的配置了

现在开始整个过程的配置。

1.在mysql1（192.168.211.138）里创建一个db1.

mysql> create database db1;Query OK, 1 row affected (0.01 sec)

检查mysql2（192.168.211.139）里是不是同步了？

    mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db1                |
| logs               |
| mysql              |
| performance_schema |
| sys                |
| wordpress          |
+--------------------+
7 rows in set (0.00 sec)

同步了。

2.在mysql3（192.168.211.142）里创建db2。

mysql> show databases;
+--------------------+
| Database           |
+--------------------+
| information_schema |
| db2                |
| logs               |
| mysql              |
| performance_schema |
| sys                |
| wordpress          |
+--------------------+
7 rows in set (0.01 sec)

3.在mysql1里配置mycat，我的mycat安装在mysql1。

我的配置文件路径：

[root@mysql1 conf]# pwd
/usr/local/mycat/conf

主要配置文件有：

  [root@mysql1 conf]# ls
autopartition-long.txt       log4j2.xml                schema.xml.bk                         server.xml.bk
auto-sharding-long.txt       migrateTables.properties  schema.xml.bk2                        sharding-by-enum.txt
auto-sharding-rang-mod.txt   myid.properties           sequence_conf.properties              wrapper.conf
cacheservice.properties      partition-hash-int.txt    sequence_db_conf.properties           zkconf
dnindex.properties           partition-range-mod.txt   sequence_distributed_conf.properties  zkdownload
ehcache.xml                  rule.xml                  sequence_time_conf.properties
index_to_charset.properties  schema.xml                server.xml
[root@mysql1 conf]#

需要用到的是:schema.xml   ##这个文件配置分表读写分离策略

rule.xml     ##这是分表规则的定义

server.xml   ##登录mycat的账户密码和防火墙的设置

4.首先配置：schema.xml

备份下原配置文件：

[root@mysql1 conf]# cp schema.xml schema.xml.bk3

清空配置文件：

[root@mysql1 conf]# echo " " >schema.xml

重新配置schema.xml，如下是我的配置文件整个内容:

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://io.mycat/"><schema name="hello" checkSQLschema="false" sqlMaxLimit="100"><!-- auto sharding by id (long) --><table name="t1" dataNode="dn1,dn2" rule="sharding-by-intfile" /><!-- global table is auto cloned to all defined data nodes ,so can joinwith any table whose sharding node is in the same data node --><table name="t2" primaryKey="ID" type="global" dataNode="dn1,dn2" /><table name="t3" dataNode="dn1" /><table name="t4" dataNode="dn2" /></schema><!-- <dataNode name="dn1$0-743" dataHost="localhost1" database="db$0-743"/> --><dataNode name="dn1" dataHost="mysql1" database="db1" /><dataNode name="dn2" dataHost="mysql3" database="db2" /><dataHost name="mysql1" maxCon="1000" minCon="10" balance="3"writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"><heartbeat>select user()</heartbeat><!-- can have multi write hosts --><writeHost host="hostM1" url="192.168.211.138:3306" user="root"password="Alex2010@"><!-- can have multi read hosts --><readHost host="hostS2" url="192.168.211.139:3306" user="root" password="Alex2010@"/></writeHost></dataHost>    <dataHost name="mysql3" 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="192.168.211.142:3306" user="root"password="Alex2010@"><!-- can have multi read hosts --><readHost host="hostS2" url="192.168.211.142:3306" user="root" password="Alex2010@"/></writeHost></dataHost>   </mycat:schema>

这些字段的解释，可以查看我前面分片规则里面的解析。

说明下datahost  balance字段的意义

balance属性

负载均衡类型，目前的取值有3种：

1. balance="0", 不开启读写分离机制，所有读操作都发送到当前可用的writeHost上。

2. balance="1"，全部的readHost与stand by writeHost参与select语句的负载均衡，简单的说，当双主双从模式(M1->S1，M2->S2，并且M1与

M2互为主备)，正常情况下，M2,S1,S2都参与select语句的负载均衡。

3. balance="2"，所有读操作都随机的在writeHost、readhost上分发。

4. balance="3"，所有读请求随机的分发到wiriterHost对应的readhost执行，writerHost不负担读压

writeType属性

负载均衡类型，目前的取值有3种：

1. writeType="0", 所有写操作发送到配置的第一个writeHost，第一个挂了切到还生存的第二个writeHost，重新启动后已切换后的为准，

切换记录在配置文件中:dnindex.properties .

2. writeType="1"，所有写操作都随机的发送到配置的writeHost，1.5以后废弃不推荐。

需要说明的是：

    <dataHost name="mysql1" maxCon="1000" minCon="10" balance="3"writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"><heartbeat>select user()</heartbeat><!-- can have multi write hosts --><writeHost host="hostM1" url="192.168.211.138:3306" user="root"password="Alex2010@"><!-- can have multi read hosts --><readHost host="hostS2" url="192.168.211.139:3306" user="root" password="Alex2010@"/></writeHost></dataHost>   

读写分离这里有两种写法：

除了上面的还可以写下面这样：

<dataHost name="mysql1" maxCon="1000" minCon="10" balance="3"writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"><heartbeat>select user()</heartbeat><!-- can have multi write hosts --><writeHost host="hostM1" url="192.168.211.138:3306" user="root"password="Alex2010@"></writeHost><writeHost host="hostM1" url="192.168.211.139:3306" user="root"password="Alex2010@"></writeHost></dataHost>   

区别是上面的那种写法，如果主服务器挂了，从服务器不能读了。

下面的这种写法，主服务器挂了，从服务器依然可以正常读取。

这里说一下，后面会做测试。

5.看看rule.xml里的配置

看分表t1的设置：

<table name="t1" dataNode="dn1,dn2" rule="sharding-by-intfile" />

分表规则是 sharding-by-intfile

看看这个的规则设置

    <tableRule name="sharding-by-intfile"><rule><columns>city</columns><algorithm>hash-int</algorithm></rule></tableRule>

为什么columns是city呢？

这个city是我设定的，计划创建表格t1(id,name,bu,city)有这四个列。我准备用city来做分片的列。

继续往下看

     </function><function name="hash-int"class="io.mycat.route.function.PartitionByFileMap"><property name="mapFile">partition-hash-int.txt</property><property name="type">1</property> <property name="defaultNode">0</property></function>

这是用的hash-int函数的设置了。其中mpfile是指要读取的配置文件。这是什么意思呢？

看看partition-hash-int.txt的内容

      [root@mysql1 conf]# cat partition-hash-int.txt
#10000=0
#10010=1
bj=0
gz=0
sz=1
[root@mysql1 conf]#

我计划的表格t1  city列有三个值，bj   gz   sz  ，这个设置的意思是：bj   gz 的数据存储到datanode1也就是mysql1，sz的数据存储

到datanode2也就是mysql3。

      <property name="type">1</property> <property name="defaultNode">0</property>

这两条参数也必须要有，type默认的值是0，而0的格式是interger，注意我们分片的列是city是字符。

6.配置server.xml，参考下官方教程，很简单。

7.到这里可以来启动mycat，登录进去创建表格，插入数据测试，是不是能够达到我们的预期目标？

[root@mysql1 conf]# mysql -uroot -p123456 -P8066 -h 127.0.0.1
mysql: [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 2
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql>

登录进来了

mysql> show databases;
+----------+
| DATABASE |
+----------+
| hello    |
+----------+
1 row in set (0.02 sec)mysql>

我们设置的逻辑库hello

mysql> use hello;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
mysql> show tables;
+-----------------+
| Tables in hello |
+-----------------+
| t1              |
| t2              |
| t3              |
| t4              |
+-----------------+
4 rows in set (0.01 sec)mysql> mysql> desc t1;
ERROR 1146 (42S02): Table 'db1.t1' doesn't exist
mysql>

注意这里有个问题，这些t1-t4的表格，看似是有，其实是假的。感觉像是BUG。表格需要我们手动创建。

创建表格：

   mysql> create table t1 (id int not null,name varchar(15) not null,bu varchar(10) not null,city varchar(5) not null);
Query OK, 0 rows affected (0.36 sec)mysql> create table t2 (id int not null,name varchar(15) not null);
Query OK, 0 rows affected (0.10 sec)mysql> create table t3 (id int not null,gongzi int not null);
Query OK, 0 rows affected (0.07 sec)mysql> create table t4 (id int not null,shui  int not null);
Query OK, 0 rows affected (0.07 sec)

看看创建的表格都放在哪?

    mysql> explain create table t1 (id int not null,name varchar(15) not null,bu varchar(10) not null,city varchar(5) not null);
+-----------+--------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL                                                                                                          |
+-----------+--------------------------------------------------------------------------------------------------------------+
| dn1       | create table t1 (id int not null,name varchar(15) not null,bu varchar(10) not null,city varchar(5) not null) |
| dn2       | create table t1 (id int not null,name varchar(15) not null,bu varchar(10) not null,city varchar(5) not null) |
+-----------+--------------------------------------------------------------------------------------------------------------+
2 rows in set (0.00 sec)mysql>

这是分片表，dn1,dn2都有

mysql> explain create table t2 (id int not null,name varchar(15) not null);
+-----------+-------------------------------------------------------------+
| DATA_NODE | SQL                                                         |
+-----------+-------------------------------------------------------------+
| dn1       | create table t2 (id int not null,name varchar(15) not null) |
| dn2       | create table t2 (id int not null,name varchar(15) not null) |
+-----------+-------------------------------------------------------------+
2 rows in set (0.00 sec)mysql>

这是全局表，dn1,dn2都有，全局表的意思是，每个dn节点都有的表而且数据保持一致。

mysql> explain create table t3 (id int not null,gongzi int not null);
+-----------+-------------------------------------------------------+
| DATA_NODE | SQL                                                   |
+-----------+-------------------------------------------------------+
| dn1       | create table t3 (id int not null,gongzi int not null) |
+-----------+-------------------------------------------------------+
1 row in set (0.00 sec)mysql>

普通表，预设就是放在dn1，正常

mysql> explain create table t4 (id int not null,shui  int not null);
+-----------+------------------------------------------------------+
| DATA_NODE | SQL                                                  |
+-----------+------------------------------------------------------+
| dn2       | create table t4 (id int not null,shui  int not null) |
+-----------+------------------------------------------------------+
1 row in set (0.00 sec)mysql>

普通表，预设就是放在dn2，正常

看看从库的情况：

mysql> show tables;
+---------------+
| Tables_in_db1 |
+---------------+
| t1            |
| t2            |
| t3            |
+---------------+
3 rows in set (0.00 sec)mysql>

除了t4没有，其他都有，正常。

插入数据：

插入t1

    mysql> insert into t1(id,name,bu,city)values(1,'am1','sy','bj');
Query OK, 1 row affected (0.38 sec)mysql> insert into t1(id,name,bu,city)values(2,'am2','cs','gz');
Query OK, 1 row affected (0.03 sec)mysql> insert into t1(id,name,bu,city)values(3,'am3','net','sz');
Query OK, 1 row affected (0.08 sec)mysql>

插入t2

mysql> insert into t2(id,name)value(4,'am4'),(5,'am5');
Query OK, 2 rows affected (0.11 sec)
Records: 2  Duplicates: 0  Warnings: 0

插入t3

mysql> insert into t3(id,gongzi)values(6,1000),(7,1200);
Query OK, 2 rows affected (0.02 sec)
Records: 2  Duplicates: 0  Warnings: 0

插入t4

mysql> insert into t4(id,shui)values(8,10),(9,8);
Query OK, 2 rows affected (0.04 sec)
Records: 2  Duplicates: 0  Warnings: 0

基础架构和环境以及达成，现在来测试：

首先，t1根据预设的目的，bj和gz的数据存放在dn1(mysql1),sz的数据存放在dn2(mysql3)

mysql> select  * from t1 where city='bj' or city='gz';
+----+------+----+------+
| id | name | bu | city |
+----+------+----+------+
|  1 | am1  | sy | bj   |
|  2 | am2  | cs | gz   |
+----+------+----+------+
2 rows in set (0.10 sec)mysql> explain select  * from t1 where city='bj' or city='gz';
+-----------+--------------------------------------------------------------+
| DATA_NODE | SQL                                                          |
+-----------+--------------------------------------------------------------+
| dn1       | SELECT * FROM t1 WHERE city = 'bj'  OR city = 'gz' LIMIT 100 |
+-----------+--------------------------------------------------------------+
1 row in set (0.00 sec)mysql> mysql> explain select  * from t1 where city='sz';
+-----------+----------------------------------------------+
| DATA_NODE | SQL                                          |
+-----------+----------------------------------------------+
| dn2       | SELECT * FROM t1 WHERE city = 'sz' LIMIT 100 |
+-----------+----------------------------------------------+
1 row in set (0.02 sec)mysql>

分表正常

测试读写分离

开启debug日志

<asyncRoot level="debug" includeLocation="true">                 ##默认level是info  改成debug后，重启mycat服务。<AppenderRef ref="Console" /><AppenderRef ref="RollingFile"/></asyncRoot>

检索数据：

检索t3的数据，t3只有mysql1有。

mysql> select * from t3;
+----+--------+
| id | gongzi |
+----+--------+
|  6 |   1000 |
|  7 |   1200 |
+----+--------+
2 rows in set (0.02 sec)

以下是mycat.log日志，可以看到是从mysql2(192.168.211.139)读取的数据

2017-12-15 01:47:23.280 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.server.NonBlockingSession.releaseConnection(NonBlockingSession.java:341))- release connection MySQLConnection [id=22, lastTime=1513320443251, user=root, schema=db1, old shema=db1, borrowed=true,fromSlaveDB=true, threadId=33, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM t3
LIMIT 100}, respHandler=SingleNodeHandler [node=dn1{SELECT *
FROM t3
LIMIT 100}, packetId=6], host=192.168.211.139, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]2017-12-15 01:54:37.777 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.server.NonBlockingSession.releaseConnection(NonBlockingSession.java:341))
- release connection MySQLConnection [id=26, lastTime=1513320877751, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=true,
threadId=31, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM t3
LIMIT 100}, respHandler=SingleNodeHandler [node=dn1{SELECT *
FROM t3
LIMIT 100}, packetId=6], host=192.168.211.139, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]

mysql> select * from t1;
+----+------+-----+------+
| id | name | bu  | city |
+----+------+-----+------+
|  3 | am3  | net | sz   |
|  1 | am1  | sy  | bj   |
|  2 | am2  | cs  | gz   |
+----+------+-----+------+
3 rows in set (0.04 sec)

日志

2017-12-15 02:02:35.818 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.MySQLConnection.synAndDoExecute(MySQLConnection.java:448))
- con need syn ,total syn cmd 1 commands SET names utf8;schema change:false con:MySQLConnection [id=29, lastTime=1513321355817, user=root,
schema=db1, old shema=db1, borrowed=true, fromSlaveDB=true, threadId=35, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM t1
LIMIT 100}, respHandler=io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler@11eaaf37, host=192.168.211.139, port=3306, statusSync=null, writeQueue=0,
modifiedSQLExecuted=false]2017-12-15 02:02:35.819 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.MySQLConnection.synAndDoExecute(MySQLConnection.java:448))
- con need syn ,total syn cmd 1 commands SET names utf8;schema change:false con:MySQLConnection [id=20, lastTime=1513321355819, user=root,
schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=65, charset=utf8, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM t1
LIMIT 100}, respHandler=io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler@11eaaf37, host=192.168.211.142, port=3306, statusSync=null, writeQueue=0,modifiedSQLExecuted=false]

多执行几次检索存在dn1的数据，查看日志，可以确认，数据都是从mysql2(192.168.211.139)读取。实现了读写分离。

8.读写两种不同写法的测试

前面有提到读写分离有两种写法，

<dataHost name="mysql1" maxCon="1000" minCon="10" balance="3"writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"><heartbeat>select user()</heartbeat><!-- can have multi write hosts --><writeHost host="hostM1" url="192.168.211.138:3306" user="root"password="Alex2010@"><!-- can have multi read hosts --><readHost host="hostS2" url="192.168.211.139:3306" user="root" password="Alex2010@"/></writeHost></dataHost>    

读写分离这里有两种写法：

除了上面的还可以写下面这样：

<dataHost name="mysql1" maxCon="1000" minCon="10" balance="3"writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100"><heartbeat>select user()</heartbeat><!-- can have multi write hosts --><writeHost host="hostM1" url="192.168.211.138:3306" user="root"password="Alex2010@"></writeHost><writeHost host="hostM1" url="192.168.211.139:3306" user="root"password="Alex2010@"></writeHost></dataHost>   

区别是上面的那种写法，如果主服务器挂了，从服务器不能读了。

下面的这种写法，主服务器挂了，从服务器依然可以正常读取。

现在服务器的写法是第一种，主服务器挂了，从服务器不能读了。执行看看

[root@mysql1 ~]# systemctl stop mysqld.service
[root@mysql1 ~]# systemctl status  mysqld.service
● mysqld.service - MySQL ServerLoaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)Active: inactive (dead) since Fri 2017-12-15 02:16:43 EST; 35s agoDocs: man:mysqld(8)

[root@mysql1 ~]# mysql -uroot -p123456 -P8066 -h127.0.0.1
mysql: [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 2
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> select * from t1;
ERROR 3000 (HY000): No MyCAT Database selected
mysql> select * from t1;
ERROR 3000 (HY000): No MyCAT Database selected

确实无法读取

测试第二种

修改schema.xml配置文件

重新启动mysql和mycat 保证环境正常

正常使用环境，我们现在关闭mysql1就是主节点

[root@mysql1 conf]# systemctl stop mysqld.service
[root@mysql1 conf]# systemctl status mysqld.service
● mysqld.service - MySQL ServerLoaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)Active: inactive (dead) since Fri 2017-12-15 02:23:55 EST; 23s agoDocs: man:mysqld(8)

检索数据看看

[root@mysql1 ~]# mysql -uroot -p123456 -P8066 -h127.0.0.1
mysql: [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 1
Server version: 5.6.29-mycat-1.6-RELEASE-20161028204710 MyCat Server (OpenCloundDB)Copyright (c) 2000, 2017, Oracle and/or its affiliates. All rights reserved.Oracle is a registered trademark of Oracle Corporation and/or its
affiliates. Other names may be trademarks of their respective
owners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> use hello;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -ADatabase changed
mysql> select * from t1;
+----+------+-----+------+
| id | name | bu  | city |
+----+------+-----+------+
|  3 | am3  | net | sz   |
|  1 | am1  | sy  | bj   |
|  2 | am2  | cs  | gz   |
+----+------+-----+------+
3 rows in set (0.46 sec)

果然如此，孰优孰劣无须说明了吧。

后记：通过环境的搭建和简单的测试，达到了设计的预期目标。