Mycat是一个开源的分布式数据库系统，不同于oracle和mysql，Mycat并没有存储引擎，但是Mycat实现了mysql协议，前段用户可以把它当做一个Proxy。其核心功能是分表分库，即将一个大表水平分割为N个小表，存储在后端mysql存储引擎里面。最新版本的Mycat不仅支持mysql，还可以支持MS SqlServer,Oracle,DB2等关系型数据库，而且还支持MongoDB这种NoSQL。Mycat对调用者屏蔽了后端存储具体实现。
Mycat的原理是先拦截用户的SQL语句并做分析：分片分析，路由分析，读写分离分析，缓存分析等，再对将该SQL语句发送到指定规则的数据库。最终将存储引擎返回的结果返回给用户.
本次搭建的Mycat读写分离和分库分表配置是基于5台服务器（1台Mac,4台Centos），架构图如下，Mac服务器上面安装Mycat；M1(OS名称：Server1,Ip:172.16.130.189)和M2(OS名称：Server2,Ip:172.16.130.190)是两个写节点; S1(OS名称：Server3,Ip:172.16.130.191)和S2(OS名称：Server4,Ip:172.16.130.192)是两个读节点。且M1和S1配置了主从复制，M2和S2也配置了主从复制。
步骤
1.在Server1,Server2,Server3和Server4中安装相同版本的Mysql，安装步骤在我之前的一篇文章中：四·安装mysql-5.7.16-linux-glibc2.5-x86_64.tar.gz（基于Centos7源码安装）
2.配置Server3同步Server1；Server4同步Server2,在我的另外一篇文章中：一.Mysql主从复制配置
其中关键代码如下
--------------------------------------Server1配置-----------------------------------------------------------
mysql> grant replication slave on *.* to 'mysqlsync'@'172.16.130.191' identified by 'mysqlsync';Query OK, 0 rows affected, 1 warning (0.01 sec)
mysql> show master status;
+------------+----------+--------------+------------------+-------------------+
| File | Position | Binlog_Do_DB | Binlog_Ignore_DB | Executed_Gtid_Set |
+------------+----------+--------------+------------------+-------------------+
| bin.000003 | 455 | | | |
+------------+----------+--------------+------------------+-------------------+
1 row in set (0.00 sec)
--------------------------------------Server3配置-----------------------------------------------------------
mysql> change master to master_host='172.16.130.189',master_user='mysqlsync',master_password='mysqlsync',master_log_file='bin.000003',master_log_pos=154;
Query OK, 0 rows affected, 2 warnings (0.01 sec)
mysql> start slave;
Query OK, 0 rows affected (0.00 sec)
3.在Server1和Server2上面分别新建一个名为mycattest的schema，且配置的访问用户名为mycattest,密码为1234
4.修改wapper.cnf
#********************************************************************
# Wrapper Properties
#********************************************************************
# Java Application
wrapper.java.command=/Library/Java/JavaVirtualMachines/jdk1.7.0_79.jdk/Contents/Home/bin/java
wrapper.working.dir=..
# Java Main class. This class must implement the WrapperListener interface
# or guarantee that the WrapperManager class is initialized. Helper
# classes are provided to do this for you. See the Integration section
# of the documentation for details.
wrapper.java.mainclass=org.tanukisoftware.wrapper.WrapperSimpleApp
set.default.REPO_DIR=lib
set.APP_BASE=.
# Java Classpath (include wrapper.jar) Add class path elements as
# needed starting from 1
wrapper.java.classpath.1=lib/wrapper.jar
wrapper.java.classpath.2=conf
wrapper.java.classpath.3=%REPO_DIR%/*
# Java Library Path (location of Wrapper.DLL or libwrapper.so)
wrapper.java.library.path.1=lib
# Java Additional Parameters
#wrapper.java.additional.1=
wrapper.java.additional.1=-DMYCAT_HOME=.
wrapper.java.additional.2=-server
wrapper.java.additional.3=-XX:MaxPermSize=64M
wrapper.java.additional.4=-XX:+AggressiveOpts
wrapper.java.additional.5=-XX:MaxDirectMemorySize=2G
wrapper.java.additional.6=-Dcom.sun.management.jmxremote
wrapper.java.additional.7=-Dcom.sun.management.jmxremote.port=1984
wrapper.java.additional.8=-Dcom.sun.management.jmxremote.authenticate=false
wrapper.java.additional.9=-Dcom.sun.management.jmxremote.ssl=false
wrapper.java.additional.10=-Xmx4G
wrapper.java.additional.11=-Xms1G
# Initial Java Heap Size (in MB)
#wrapper.java.initmemory=3
# Maximum Java Heap Size (in MB)
#wrapper.java.maxmemory=64
# Application parameters. Add parameters as needed starting from 1
wrapper.app.parameter.1=io.mycat.MycatStartup
wrapper.app.parameter.2=start
#********************************************************************
# Wrapper Logging Properties
#********************************************************************
# Format of output for the console. (See docs for formats)
wrapper.console.format=PM
# Log Level for console output. (See docs for log levels)
wrapper.console.loglevel=INFO
# Log file to use for wrapper output logging.
wrapper.logfile=logs/wrapper.log
# Format of output for the log file. (See docs for formats)
wrapper.logfile.format=LPTM
# Log Level for log file output. (See docs for log levels)
wrapper.logfile.loglevel=INFO
# Maximum size that the log file will be allowed to grow to before
# the log is rolled. Size is specified in bytes. The default value
# of 0, disables log rolling. May abbreviate with the 'k' (kb) or
# 'm' (mb) suffix. For example: 10m = 10 megabytes.
wrapper.logfile.maxsize=0
# Maximum number of rolled log files which will be allowed before old
# files are deleted. The default value of 0 implies no limit.
wrapper.logfile.maxfiles=0
# Log Level for sys/event log output. (See docs for log levels)
wrapper.syslog.loglevel=NONE
#********************************************************************
# Wrapper Windows Properties
#********************************************************************
# Title to use when running as a console
wrapper.console.title=Mycat-server
#********************************************************************
# Wrapper Windows NT/2000/XP Service Properties
#********************************************************************
# WARNING - Do not modify any of these properties when an application
# using this configuration file has been installed as a service.
# Please uninstall the service before modifying this section. The
# service can then be reinstalled.
# Name of the service
wrapper.ntservice.name=mycat
# Display name of the service
wrapper.ntservice.displayname=Mycat-server
# Description of the service
wrapper.ntservice.description=The project of Mycat-server
# Service dependencies. Add dependencies as needed starting from 1
wrapper.ntservice.dependency.1=
# Mode in which the service is installed. AUTO_START or DEMAND_START
wrapper.ntservice.starttype=AUTO_START
# Allow the service to interact with the desktop.
wrapper.ntservice.interactive=false
wrapper.ping.timeout=120
configuration.directory.in.classpath.first=conf
5.修改server.xml
<?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="defaultSqlParser">druidparser</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="sequnceHandlerType">2</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-->
<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="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">1</property>
<!--
单位为m
-->
<property name="memoryPageSize">1m</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">true</property>
</system>
<!-- 全局SQL防火墙设置 -->
<!--
<firewall>
<whitehost>
<host host="127.0.0.1" user="mycat"/>
<host host="127.0.0.2" user="mycat"/>
</whitehost>
<blacklist check="false">
</blacklist>
</firewall>
-->
<user name="test1">
<property name="password">123456</property>
<property name="schemas">TESTDB</property>
<!-- 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="test2">
<property name="password">user</property>
<property name="schemas">TESTDB</property>
<property name="readOnly">true</property>
</user>
</mycat:server>
6.修改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">
<table name="g_user" primaryKey="user_id" dataNode="Server1,Server2" rule="sharding-by-mod" />
</schema>
<dataNode name="Server1" dataHost="172.16.130.189" database="mycattest" />
<dataNode name="Server2" dataHost="172.16.130.190" database="mycattest" />
<!-- data host definition for oe -->
<dataHost name="172.16.130.189" 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="Server1" url="172.16.130.189:3306" user="mycattest" password="1234">
<!-- can have multi read hosts -->
<readHost host="Server3" url="172.16.130.191:3306" user="mycattest" password="1234"/>
</writeHost>
</dataHost>
<dataHost name="172.16.130.190" 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="Server2" url="172.16.130.190:3306" user="mycattest" password="1234" >
<!-- can have multi read hosts -->
<readHost host="Server4" url="172.16.130.192:3306" user="mycattest" password="1234"/>
</writeHost>
<!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> -->
</dataHost>
</mycat:schema>
7.启动Mycat
bogon:bin Randy$ ./mycat console
Running Mycat-server...
wrapper | --> Wrapper Started as Console
wrapper | Launching a JVM...
jvm 1 | Wrapper (Version 3.2.3) http://wrapper.tanukisoftware.org
jvm 1 | Copyright 1999-2006 Tanuki Software, Inc. All Rights Reserved.
jvm 1 |
jvm 1 | 2017-03-18 21:21:18,296 [INFO ][WrapperSimpleAppMain] total resouces of dataHost 172.16.130.190 is :2 (io.mycat.backend.datasource.PhysicalDBPool:PhysicalDBPool.java:100)
jvm 1 | 2017-03-18 21:21:18,298 [INFO ][WrapperSimpleAppMain] total resouces of dataHost 172.16.130.189 is :2 (io.mycat.backend.datasource.PhysicalDBPool:PhysicalDBPool.java:100)
jvm 1 | 2017-03-18 21:21:18,307 [INFO ][WrapperSimpleAppMain] create layer cache pool TableID2DataNodeCache of type encache ,default cache size 10000 ,default expire seconds18000 (io.mycat.cache.CacheService:CacheService.java:125)
jvm 1 | 2017-03-18 21:21:18,308 [INFO ][WrapperSimpleAppMain] create child Cache: TESTDB_ORDERS for layered cache TableID2DataNodeCache, size 50000, expire seconds 18000 (io.mycat.cache.DefaultLayedCachePool:DefaultLayedCachePool.java:80)
jvm 1 | 2017-03-18 21:21:18,329 [DEBUG][WrapperSimpleAppMain] Configuring ehcache from ehcache.xml found in the classpath: file:/Users/Randy/Developer/16InstallSoftware/mycat/conf/ehcache.xml (net.sf.ehcache.config.ConfigurationFactory:ConfigurationFactory.java:132)
******测试：
由于我在上面的配置中，定了表g_user按照sharding-by-mod算法规则来分片，
<table name="g_user" primaryKey="user_id" dataNode="Server1,Server2" rule="sharding-by-mod" />
通过Mycat插入了两条数据
insert into g_user(id) values(1);
insert into g_user(id) values(2);
通过查询，发现id=1的数据被插入到了M2和S2数据库服务器，而id=2的数据被插入到了M1和S1数据库