之前的读写分离（一主一从）https://www.cnblogs.com/zwh0910/p/17267627.html
架构如下：
从该系统架构中，可以看出：
（1）、数据库从之前的单节点变为多节点提供服务
（2）、主节点数据，同步到从节点数据
（3）、应用程序需要连接到 2个数据库节点，并且在程序内部实现判断读写操作
但是上面的架构存在问题：所有操作都是将数据写入到主节点中，再同步到从节点。但是主节点只是一个单节点在存储数据，我们并没有解决数据存储量的问题，要想解决这个问题，必须采用分片，即有多个主节点，或者说多对主从节点，多个主节点看作是一个整体，可以把这多个主节点看作是一个大节点去存储数据
有两个数据库集群
MySQL集群1：
|
主机 |
端口 | 容器名称 | 角色 |
| 云服务器IP | 3301 | mysql-master | master |
| 云服务器IP | 3302 | mysql-slave | slav |
MySQL集群2：
|
主机 |
端口 | 容器名称 | 角色 |
| 云服务器IP | 3401 | mysql-master2 | master |
| 云服务器IP | 3402 | mysql-slave2 | slav |
下面的操作在这篇博客的基础上修改mycat配置：https://www.cnblogs.com/zwh0910/p/17267627.html#autoid-1-7-0
server.xml文件不用修改，配置如下：
<?xml version="1.0" encoding="UTF-8"?> <!-- - - Licensed under the Apache License, Version 2.0 (the "License"); - you may not use this file except in compliance with the License. - You may obtain a copy of the License at - - http://www.apache.org/licenses/LICENSE-2.0 - - Unless required by applicable law or agreed to in writing, software - distributed under the License is distributed on an "AS IS" BASIS, - WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. - See the License for the specific language governing permissions and - limitations under the License. --> <!DOCTYPE mycat:server SYSTEM "server.dtd"> <mycat:server xmlns:mycat="http://io.mycat/"> <system> <property name="nonePasswordLogin">0</property> <!-- 0为需要密码登陆、1为不需要密码登陆 ,默认为0，设置为1则需要指定默认账户--> <property name="ignoreUnknownCommand">0</property><!-- 0遇上没有实现的报文(Unknown command:),就会报错、1为忽略该报文，返回ok报文。 在某些mysql客户端存在客户端已经登录的时候还会继续发送登录报文,mycat会报错,该设置可以绕过这个错误--> <property name="useHandshakeV10">1</property> <property name="removeGraveAccent">1</property> <property name="useSqlStat">0</property> <!-- 1为开启实时统计、0为关闭 --> <property name="useGlobleTableCheck">0</property> <!-- 1为开启全加班一致性检测、0为关闭 --> <property name="sqlExecuteTimeout">300</property> <!-- SQL 执行超时 单位:秒--> <property name="sequnceHandlerType">1</property> <!--<property name="sequnceHandlerPattern">(?:(\s*next\s+value\s+for\s*MYCATSEQ_(\w+))(,|\)|\s)*)+</property> INSERT INTO `travelrecord` (`id`,user_id) VALUES ('next value for MYCATSEQ_GLOBAL',"xxx"); --> <!--必须带有MYCATSEQ_或者 mycatseq_进入序列匹配流程 注意MYCATSEQ_有空格的情况--> <property name="sequnceHandlerPattern">(?:(\s*next\s+value\s+for\s*MYCATSEQ_(\w+))(,|\)|\s)*)+</property> <property name="subqueryRelationshipCheck">false</property> <!-- 子查询中存在关联查询的情况下,检查关联字段中是否有分片字段 .默认 false --> <property name="sequenceHanlderClass">io.mycat.route.sequence.handler.HttpIncrSequenceHandler</property> <!-- <property name="useCompression">1</property>--> <!--1为开启mysql压缩协议--> <!-- <property name="fakeMySQLVersion">5.6.20</property>--> <!--设置模拟的MySQL版本号--> <!-- <property name="processorBufferChunk">40960</property> --> <!-- <property name="processors">1</property> <property name="processorExecutor">32</property> --> <!--默认为type 0: DirectByteBufferPool | type 1 ByteBufferArena | type 2 NettyBufferPool --> <property name="processorBufferPoolType">0</property> <!--默认是65535 64K 用于sql解析时最大文本长度 --> <!--<property name="maxStringLiteralLength">65535</property>--> <!--<property name="sequnceHandlerType">0</property>--> <!--<property name="backSocketNoDelay">1</property>--> <!--<property name="frontSocketNoDelay">1</property>--> <!--<property name="processorExecutor">16</property>--> <!-- <property name="serverPort">8066</property> <property name="managerPort">9066</property> <property name="idleTimeout">300000</property> <property name="bindIp">0.0.0.0</property> <property name="dataNodeIdleCheckPeriod">300000</property> 5 * 60 * 1000L; //连接空闲检查 <property name="frontWriteQueueSize">4096</property> <property name="processors">32</property> --> <!--分布式事务开关，0为不过滤分布式事务，1为过滤分布式事务（如果分布式事务内只涉及全局表，则不过滤），2为不过滤分布式事务,但是记录分布式事务日志--> <property name="handleDistributedTransactions">0</property> <!-- off heap for merge/order/group/limit 1开启 0关闭 --> <property name="useOffHeapForMerge">0</property> <!-- 单位为m --> <property name="memoryPageSize">64k</property> <!-- 单位为k --> <property name="spillsFileBufferSize">1k</property> <property name="useStreamOutput">0</property> <!-- 单位为m --> <property name="systemReserveMemorySize">384m</property> <!--是否采用zookeeper协调切换 --> <property name="useZKSwitch">false</property> <!-- XA Recovery Log日志路径 --> <!--<property name="XARecoveryLogBaseDir">./</property>--> <!-- XA Recovery Log日志名称 --> <!--<property name="XARecoveryLogBaseName">tmlog</property>--> <!--如果为 true的话 严格遵守隔离级别,不会在仅仅只有select语句的时候在事务中切换连接--> <property name="strictTxIsolation">false</property> <property name="useZKSwitch">true</property> <!--如果为0的话,涉及多个DataNode的catlet任务不会跨线程执行--> <property name="parallExecute">0</property> </system> <!-- 全局SQL防火墙设置 --> <!--白名单可以使用通配符%或着*--> <!--例如<host host="127.0.0.*" user="root"/>--> <!--例如<host host="127.0.*" user="root"/>--> <!--例如<host host="127.*" user="root"/>--> <!--例如<host host="1*7.*" user="root"/>--> <!--这些配置情况下对于127.0.0.1都能以root账户登录--> <!-- <firewall> <whitehost> <host host="1*7.0.0.*" user="root"/> </whitehost> <blacklist check="false"> </blacklist> </firewall> --> <user name="root" defaultAccount="true"> <property name="password">123456</property> <property name="schemas">nacos_config</property> <property name="defaultSchema">nacos_config</property> <!--No MyCAT Database selected 错误前会尝试使用该schema作为schema，不设置则为null,报错 --> <!-- 表级 DML 权限设置 --> <!-- <privileges check="false"> <schema name="TESTDB" dml="0110" > <table name="tb01" dml="0000"></table> <table name="tb02" dml="1111"></table> </schema> </privileges> --> </user> <user name="user"> <property name="password">user</property> <property name="schemas">nacos_config</property> <property name="readOnly">true</property> <property name="defaultSchema">nacos_config</property> </user> </mycat:server>
修改schema.xml文件
<?xml version="1.0"?> <!DOCTYPE mycat:schema SYSTEM "schema.dtd"> <mycat:schema xmlns:mycat="http://io.mycat/"> <schema name="nacos_config" checkSQLschema="true" sqlMaxLimit="100"> <!-- auto sharding by id (long) --> <!--splitTableNames 启用<table name 属性使用逗号分割配置多个表,即多个表使用这个配置--> <table name="tb_ad,users" dataNode="dn1,dn2" rule="mod-long"/> <!-- <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="nacos_config" /> <dataNode name="dn2" dataHost="localhost2" database="nacos_config" /> <!--<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="3" writeType="1" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100"> <heartbeat>select user()</heartbeat> <!-- can have multi write hosts --> <writeHost host="hostM1" url="localhost:3401" user="root" password="123456"> <readHost host="R1" url="localhost:3402" user="root" password="123456"/> </writeHost> <!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> --> </dataHost> <dataHost name="localhost2" maxCon="1000" minCon="10" balance="3" writeType="1" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100"> <heartbeat>select user()</heartbeat> <!-- can have multi write hosts --> <writeHost host="hostM2" url="localhost:3301" user="root" password="123456"> <readHost host="R2" url="localhost:3302" user="root" password="123456"/> </writeHost> <!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> --> </dataHost> </mycat:schema>
修改rule.xml
<function name="mod-long" class="io.mycat.route.function.PartitionByMod"> <!-- how many data nodes --> <property name="count">2</property> </function>
此时启动了四个mysql
CONTAINER ID IMAGE COMMAND CREATED STATUS PORTS NAMES 8c6de74fbbb9 mysql:8.0.26 "docker-entrypoint.s…" 18 hours ago Up 18 hours 33060/tcp, 0.0.0.0:3402->3306/tcp, :::3402->3306/tcp mysql-slave2 88af7650cb6f mysql:8.0.26 "docker-entrypoint.s…" 18 hours ago Up 16 hours 33060/tcp, 0.0.0.0:3401->3306/tcp, :::3401->3306/tcp mysql-master2 3b754acc9a3e mysql:8.0.26 "docker-entrypoint.s…" 3 days ago Up 17 hours 33060/tcp, 0.0.0.0:3302->3306/tcp, :::3302->3306/tcp mysql-slave b21ba08b7665 mysql:8.0.26 "docker-entrypoint.s…" 3 days ago Up 2 seconds 33060/tcp, 0.0.0.0:3301->3306/tcp, :::3301->3306/tcp mysql-master
启动mycat
./mycat console
再执行脚本
./startup_nowrap.sh
现在我们来测试，在mycat中创建表
-- 创建表 CREATE TABLE `TB_AD` ( `id` bigint(20) NOT NULL AUTO_INCREMENT, `type` int(10) DEFAULT NULL COMMENT '广告类型', `title` varchar(100) DEFAULT NULL COMMENT '描述', `url` varchar(200) DEFAULT NULL COMMENT '图片URL地址', `created` datetime DEFAULT NULL, `updated` datetime DEFAULT NULL, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=1 DEFAULT CHARSET=utf8 COMMENT='广告表';
执行结果：
此时四个节点的nacos_config表中都有TB_AD表
插入数据
INSERT INTO `TB_AD` (`id`, `type`, `title`, `url`, `created`, `updated`) VALUES (1, '1', 'UniCity万科天空之城', 'http://itcast-haoke.oss-cn- qingdao.aliyuncs.com/images/2018/11/26/15432029097062227.jpg', '2018-11-26 11:28:49', '2018-11-26 11:28:51'); INSERT INTO `TB_AD` (`id`, `type`, `title`, `url`, `created`, `updated`) VALUES (2, '1', '天和尚海庭前', 'http://itcast-haoke.oss-cn- qingdao.aliyuncs.com/images/2018/11/26/1543202958579877.jpg', '2018-11-26 11:29:27', '2018-11-26 11:29:29'); INSERT INTO `TB_AD` (`id`, `type`, `title`, `url`, `created`, `updated`) VALUES (3, '1', '[奉贤 南桥] 光语著', 'http://itcast-haoke.oss-cn- qingdao.aliyuncs.com/images/2018/11/26/15432029946721854.jpg', '2018-11-26 11:30:04', '2018-11-26 11:30:06'); INSERT INTO `TB_AD` (`id`, `type`, `title`, `url`, `created`, `updated`) VALUES (4, '1', '[上海周边 嘉兴] 融创海逸长洲', 'http://itcast-haoke.oss-cn- qingdao.aliyuncs.com/images/2018/11/26/15432030275359146.jpg', '2018-11-26 11:30:49', '2018-11-26 11:30:53');
发现报错：> 1146 - Table 'nacos_config.tb_ad' doesn't exist
我们将表名修改为TB_AD，就可以执行成功。此时发现两个主库的数据如下：
主1
从1
主2
从2
查看mycat
发现id没有进行排序，
可以看到，数据已经从 2个分片中进行了汇总。
执行修改命令
update TB_AD set title = '葛洲坝' where id=2;
发现主1和从1进行了修改
