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mycat基础实验之主从配置读写分离和分表

发表于:2025-02-03 作者:千家信息网编辑
千家信息网最后更新 2025年02月03日,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
千家信息网最后更新 2025年02月03日mycat基础实验之主从配置读写分离和分表

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]# lsautopartition-long.txt       log4j2.xml                schema.xml.bk                         server.xml.bkauto-sharding-long.txt       migrateTables.properties  schema.xml.bk2                        sharding-by-enum.txtauto-sharding-rang-mod.txt   myid.properties           sequence_conf.properties              wrapper.confcacheservice.properties      partition-hash-int.txt    sequence_db_conf.properties           zkconfdnindex.properties           partition-range-mod.txt   sequence_distributed_conf.properties  zkdownloadehcache.xml                  rule.xml                  sequence_time_conf.propertiesindex_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:

                                        
select user() select user()

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:

                     select user()                                                                                                               

读写分离这里有两种写法:

除了上面的还可以写下面这样:

                select user()                                                                                               

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:

分表规则是 sharding-by-intfile

看看这个的规则设置

                                                city                        hash-int                        

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

                             partition-hash-int.txt                1                 0        

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=1bj=0gz=0sz=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。

      1         0

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 127.0.0.1mysql: [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 2Server 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 itsaffiliates. Other names may be trademarks of their respectiveowners.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 namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> 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 existmysql>


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

                 ##默认level是info  改成debug后,重启mycat服务。                                


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 [$_NIOREACTOR-0-RW] (io.mycat.server.NonBlockingSession.releaseConnection(NonBlockingSession.java:341)) - release connection MySQLConnection [id=22, lastTime=1513320443251, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=true, threadId=33, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *FROM t3LIMIT 100}, respHandler=SingleNodeHandler [node=dn1{SELECT *FROM t3LIMIT 100}, packetId=6], host=192.168.211.139, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]2017-12-15 01:54:37.777 DEBUG [$_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 t3LIMIT 100}, respHandler=SingleNodeHandler [node=dn1{SELECT *FROM t3LIMIT 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 [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.MySQLConnection.synAndDoExecute(MySQLConnection.java:448)) - con need syn ,total syn cmd 1 commands SET names utf8;schema change:false con:MySQLConnection [id=29, lastTime=1513321355817, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=true, threadId=35, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *FROM t1LIMIT 100}, respHandler=io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler@11eaaf37, host=192.168.211.139, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]2017-12-15 02:02:35.819 DEBUG [$_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 t1LIMIT 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,

                select user()                                                                                                               

读写分离这里有两种写法:

除了上面的还可以写下面这样:

                select user()                                                                                               


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 Server   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)   Active: inactive (dead) since Fri 2017-12-15 02:16:43 EST; 35s ago     Docs: man:mysqld(8)
[root@mysql1 ~]# mysql -uroot -p123456 -P8066 -h227.0.0.1mysql: [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 2Server 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 itsaffiliates. Other names may be trademarks of their respectiveowners.Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.mysql> select * from t1;ERROR 3000 (HY000): No MyCAT Database selectedmysql> 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 Server   Loaded: loaded (/usr/lib/systemd/system/mysqld.service; enabled; vendor preset: disabled)   Active: inactive (dead) since Fri 2017-12-15 02:23:55 EST; 23s ago     Docs: man:mysqld(8)


检索数据看看

[root@mysql1 ~]# mysql -uroot -p123456 -P8066 -h227.0.0.1mysql: [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 1Server 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 itsaffiliates. Other names may be trademarks of their respectiveowners.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 namesYou can turn off this feature to get a quicker startup with -ADatabase changedmysql> 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。


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