mycat读写分离与主从切换

1，分库分表的优缺点、以及为什么分表方式无法成为主流？

分表：在台服务器上，优点是易维护，类似表分区，缺点是在一台db服务器上，无法分担IO、负载集中。

分库：在多台服务器上，优点是分担IO、负载均衡，缺点是较不易维护、数据统计以及jion操作有些难度。

 

数据库切分的目的是为了分担IO、负载均衡，分表无法达到最佳的要求，所以无法成为主流。

2，准备主库

tar -xvf mysql-5.6.12.tar.gz

cd mysql-5.6.12

 

time cmake .-DCMAKE_INSTALL_PREFIX=/usr/local/mysql56m1-DMYSQL_DATADIR=/home/data/mysql56m1/data -DWITH_INNOBASE_STORAGE_ENGINE=1-DMYSQL_UNIX_ADDR==/usr/local/mysql56m1/mysql.sock -DMYSQL_USER=mysql-DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci

 

time make

time make install

 

 chown -R mysql /home/data/

 chgrp -R mysql /home/data/

 chown -R mysql /usr/local/mysql

 

 chown -R mysql /usr/local/mysql56m1

 chgrp -R mysql /usr/local/mysql

 

 chgrp -R mysql /usr/local/mysql56m1/

 mkdir -p /home/data/mysql56m1/binlog/

 chown -R mysql.mysql/home/data/mysql56m1/binlog/

 mkdir -p /home/data/mysql5610/binlog/

 chown -R mysql.mysql /home/data/

 

cd /usr/local/mysql56m1

time scripts/mysql_install_db  --user=mysql --basedir=/usr/local/mysql56m1--datadir=/home/data/mysql56m1/data --defaults-file=/usr/local/mysql56m1/my.cnf

 

cp support-files/mysql.server/etc/init.d/mysql56m1

chmod 700 /etc/init.d/mysql56m1

echo "exportPATH=$PATH:/usr/local/mysql56m1/bin">>/etc/profile

source /etc/profile

chkconfig --add mysql56m1

 

service mysql56m1 start

 

3，准备备库

 

tar -xvf mysql-5.6.12.tar.gz

cd mysql-5.6.12

 

time cmake .-DCMAKE_INSTALL_PREFIX=/usr/local/mysql56s1-DMYSQL_DATADIR=/home/data/mysql56s1/data -DWITH_INNOBASE_STORAGE_ENGINE=1-DMYSQL_UNIX_ADDR==/usr/local/mysql56s1/mysql.sock -DMYSQL_USER=mysql-DDEFAULT_CHARSET=utf8 -DDEFAULT_COLLATION=utf8_general_ci

 

time make

time make install

 

 

 chown -R mysql /home/data/

 chgrp -R mysql /home/data/

 chown -R mysql /usr/local/mysql

 

 chown-R mysql /usr/local/mysql56s1

 chgrp -R mysql /usr/local/mysql

 

 chgrp -R mysql /usr/local/mysql56s1/

 mkdir -p /home/data/mysql56s1/binlog/

 chown -R mysql.mysql/home/data/mysql56s1/binlog/

 mkdir -p /home/data/mysql5610/binlog/

 chown -R mysql.mysql /home/data/

 

 

cd /usr/local/mysql56s1

time scripts/mysql_install_db  --user=mysql --basedir=/usr/local/mysql56s1--datadir=/home/data/mysql56s1/data --defaults-file=/usr/local/mysql56s1/my.cnf

 

cp support-files/mysql.server/etc/init.d/mysql56s1

chmod 700 /etc/init.d/mysql56s1

echo "exportPATH=$PATH:/usr/local/mysql56s1/bin">>/etc/profile

source /etc/profile

chkconfig --add mysql56s1

service mysql56s1 start

 

 

 

4，搭建主从环境

在一台服务器，主3317端口，从3327端口。

主库备库上，添加复制帐号：

GRANT REPLICATION SLAVE ON *.* TO'repl'@'10.254.%' IDENTIFIED BY 'mycatms';

 

在备库上3327端口上设置复制：

stop slave;

reset slave;

change master to master_user='repl',master_password='mycatms', master_host='127.0.0.1',master_port=3317,master_log_file='mysql-bin.000003',master_log_pos=840;

start slave;

show slave status\G;

 

主库：3317端口

从库：3327端口

数据同步测试：

 

 

5，数据同步测试：

配置schema.xml：

然后修改mycat的schema.xml：

balance为1：让全部的readHost及备用的writeHost参与select的负载均衡。

switchType为2：基于MySQL主从同步的状态决定是否切换。

heartbeat：主从切换的心跳语句必须为showslave status。

 

5.0 数据录入：

mysql>explain create table company(id int not null primary key,name varchar(100));

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

|DATA_NODE | SQL                                                                |

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

|dn1       | create table company(id intnot null primary key,name varchar(100)) |

|dn2       | create table company(id intnot null primary key,name varchar(100)) |

|dn3       | create table company(id intnot null primary key,name varchar(100)) |

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

3 rowsin set (0.00 sec)

 

mysql>create table company(id int not null primary key,name varchar(100));

QueryOK, 0 rows affected (0.01 sec)

 

mysql>explain  insert into company(id,name)values(1,'alibaba');

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

|DATA_NODE | SQL                                              |

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

|dn1       | insert into company(id,name)values(1,'alibaba') |

|dn2       | insert into company(id,name)values(1,'alibaba') |

|dn3       | insert into company(id,name)values(1,'alibaba') |

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

3 rowsin set (0.10 sec)

 

mysql>  insert into company(id,name)values(1,'alibaba');

QueryOK, 1 row affected (0.00 sec)

 

mysql>

 

5.1主库验证：

[root@wgq_idc_squid_1_11 logs]#/usr/local/mysql56m1/bin/mysql -uroot -p -P3317--socket=/usr/local/mysql56m1/mysql.sock -e "select @@port;select * fromdb1.company";

Enter password:

+--------+

| @@port |

+--------+

|  3317 |

+--------+

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

| id | name    |

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

|  1| alibaba |

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

[root@wgq_idc_squid_1_11 logs]#

 

 

5.2从库验证：

[root@wgq_idc_squid_1_11 logs]#/usr/local/mysql56s1/bin/mysql -uroot -p -P3327--socket=/usr/local/mysql56s1/mysql.sock -e "select @@port;select * fromdb1.company";

Enter password:

+--------+

| @@port |

+--------+

|  3327 |

+--------+

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

| id | name    |

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

|  1| alibaba |

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

[root@wgq_idc_squid_1_11 logs]#

 

6，读写分离模式

6.1然后修改mycat的schema.xml：

balance为1：让全部的readHost及备用的writeHost参与select的负载均衡。

switchType为2：基于MySQL主从同步的状态决定是否切换。

heartbeat：主从切换的心跳语句必须为showslave status。

有配置读节点：

    

                writeType="0"dbType="mysql" dbDriver="native"switchType="2" slaveThreshold="100">

                show slavestatus

               

               

                       

               

               

       

 

打开

 

6.2 打开debug模式

[root@wgq_idc_squid_1_11 conf]# vimlog4j.xml

变成 

 

6.3 执行查询读操作

在mycat窗口上执行select操作：

mysql> explain select * from companywhere id=1;

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

| DATA_NODE | SQL                                          |

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

| dn3      | SELECT * FROM company WHERE id = 1 LIMIT 100 |

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

1 row in set (0.14 sec)

 

mysql> select * from company where id=1;

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

| id | name    |

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

|  1| alibaba |

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

1 row in set (0.01 sec)

 

mysql>

后台日志显示出只在3327上执行：

01/18 01:35:01.536  DEBUG [$_NIOREACTOR-3-RW](PhysicalDBPool.java:452) -select read source hostS2 fordataHost:wgq_idc_mon_1_11

01/18 01:35:01.537  DEBUG [$_NIOREACTOR-3-RW](MySQLConnection.java:445) -con need syn ,total syn cmd 2 commands SET nameslatin1;SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;schemachange:false con:MySQLConnection [id=14, lastTime=1453052101537, user=root,schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=3326,charset=latin1, txIsolation=0, autocommit=true, attachment=dn1{SELECT *

FROM company

WHERE id = 1

LIMIT 100}, respHandler=SingleNodeHandler[node=dn1{SELECT *

FROM company

WHERE id = 1

LIMIT 100}, packetId=0], host=127.0.0.1,port=3327, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]

01/18 01:35:01.546  DEBUG [$_NIOREACTOR-2-RW](NonBlockingSession.java:229) -release connection MySQLConnection [id=14,lastTime=1453052101529, user=root, schema=db1, old shema=db1, borrowed=true,fromSlaveDB=false, threadId=3326, charset=latin1, txIsolation=3,autocommit=true, attachment=dn1{SELECT *

FROM company

WHERE id = 1

LIMIT 100}, respHandler=SingleNodeHandler[node=dn1{SELECT *

FROM company

WHERE id = 1

LIMIT 100}, packetId=5], host=127.0.0.1,port=3327,statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@7fb43f0f,writeQueue=0, modifiedSQLExecuted=false]

01/18 01:35:01.547  DEBUG [$_NIOREACTOR-2-RW] (PhysicalDatasource.java:403)-release channel MySQLConnection [id=14, lastTime=1453052101529, user=root,schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=3326,charset=latin1, txIsolation=3, autocommit=true, attachment=null,respHandler=null, host=127.0.0.1, port=3327, statusSync=null, writeQueue=0,modifiedSQLExecuted=false]

^C

 

 

 

6.4 执行写操作

Mycat窗口写操作：

 

后台log显示写操作在3317上：

01/18 01:39:54.550  DEBUG [$_NIOREACTOR-3-RW](NonBlockingSession.java:229) -release connection MySQLConnection [id=7, lastTime=1453052394535,user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false,threadId=163, charset=latin1, txIsolation=3, autocommit=true,attachment=dn3{insert into company values(3,'baidu')},respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@42bed1e7,host=127.0.0.1, port=3317, statusSync=null, writeQueue=0,modifiedSQLExecuted=true]

01/18 01:39:54.550  DEBUG [$_NIOREACTOR-3-RW](PhysicalDatasource.java:403) -release channel MySQLConnection [id=7,lastTime=1453052394535, user=root, schema=db3, old shema=db3, borrowed=true,fromSlaveDB=false, threadId=163, charset=latin1, txIsolation=3,autocommit=true, attachment=null, respHandler=null, host=127.0.0.1, port=3317,statusSync=null, writeQueue=0, modifiedSQLExecuted=false]

01/18 01:39:54.550  DEBUG [$_NIOREACTOR-3-RW](MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:truefrom MySQLConnection [id=3, lastTime=1453052394535, user=root, schema=db2, oldshema=db2, borrowed=true, fromSlaveDB=false, threadId=162, charset=latin1,txIsolation=3, autocommit=true, attachment=dn2{insert into companyvalues(3,'baidu')},respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@42bed1e7,host=127.0.0.1, port=3317, statusSync=null, writeQueue=0, modifiedSQLExecuted=true]

01/18 01:39:54.551  DEBUG [$_NIOREACTOR-3-RW](NonBlockingSession.java:229) -release connection MySQLConnection [id=3,lastTime=1453052394535, user=root, schema=db2, old shema=db2, borrowed=true,fromSlaveDB=false, threadId=162, charset=latin1, txIsolation=3,autocommit=true, attachment=dn2{insert into company values(3,'baidu')},respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@42bed1e7,host=127.0.0.1, port=3317, statusSync=null, writeQueue=0,modifiedSQLExecuted=true]

01/18 01:39:54.551  DEBUG [$_NIOREACTOR-3-RW](PhysicalDatasource.java:403) -release channel MySQLConnection [id=3,lastTime=1453052394535, user=root, schema=db2, old shema=db2, borrowed=true,fromSlaveDB=false, threadId=162, charset=latin1, txIsolation=3, autocommit=true,attachment=null, respHandler=null, host=127.0.0.1, port=3317, statusSync=null,writeQueue=0, modifiedSQLExecuted=false]

 

Check下主从数据是否都已经写入了：

主库3317端口：

从裤3327端口：

 

7，主从切换测试

 

7.1  mycat托管配置如下

       

                writeType="0"dbType="mysql" dbDriver="native"switchType="2" slaveThreshold="100">

                show slavestatus

               

                

                       

               

               

       

 

7.2 关闭主库，写操作切换到从裤3327端口

关闭主库

[root@wgq_idc_squid_1_11 conf]# servicemysql56m1 stop

Shutting down MySQL....                                    [确定]

[root@wgq_idc_squid_1_11 conf]#

Mycat后台报错：

01/18 01:50:01.037   INFO [Timer0] (PhysicalDatasource.java:373)-not ilde connection in pool,create new connection for hostM1 of schema db1

01/18 01:50:01.038   INFO [$_NIOConnector](AbstractConnection.java:458) -close connection,reason:java.net.ConnectException:拒绝连接 ,MySQLConnection [id=0, lastTime=1453053001035, user=root,schema=db1, old shema=db1, borrowed=false, fromSlaveDB=false, threadId=0,charset=utf8, txIsolation=0, autocommit=true, attachment=null,respHandler=null, host=127.0.0.1, port=3317, statusSync=null, writeQueue=0,modifiedSQLExecuted=false]

01/18 01:50:01.038   INFO [$_NIOConnector] (SQLJob.java:111)-can't get connection for sql :show slave status

01/18 01:50:01.038   WARN [$_NIOREACTOR-1-RW](MySQLDetector.java:139) -found MySQL master/slave Replication err !!!DBHostConfig [hostName=hostR1, url=127.0.0.1:3327]error reconnecting to master'[email protected]:3317' - retry-time: 60 retries: 1

0

看到主从失效，因为主down了。

 

因为我们通过mycat配置了主从切换模式，现在3317端口主库down了，那么写库应该自动切换到从裤3327上面，如果在mycat上面写入，就应该写到3327端口的从库了，验证如下：

（1）在mycat窗口录入数据：

（2）在3327端口从裤验证数据：

 

看到3327端口的数据有新录入的4,meituan的数据。表明验证成功。

(3) dnindex属性文件中writeHost已经变成了第二个了，如下所示：

7.3 再启动原来的主库3317端口，在mycat上做写操作，后台mysql写库还是原来的从库3327端口：

这个时候就会报错，主从连接失败，原因是从库3327会再重新从主库3317同步所有的数据，但是从库已经有了，所以就会报错，如下所示：

 

我采用

stop slave;

 setglobal sql_slave_skip_counter=1;

 start slave;

 showslave status\G;

一个个忽略过后，就正常了，没有报错：

 

但是这个时候如果再在mycat窗口上录入数据，debug分析面，还是会写入到3327里面去：

后台debug日志：

 

OK，至此，mycat主从切换成功