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
druidparser
0
0
2
0
0
1
1m
1k
0
384m
true
123456
TESTDB
user
TESTDB
true
6.修改schema.xml
select user()
select user()
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，
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
