一 環境
1.1 結構
192.168.132.125 mycat
192.168.132.121 master
192.168.132.122 slave
主從已經配置完成
1.2 安裝mycat
192.168.132.125安裝mycat
[root@mycat ~]# cd /usr/local/src/
[root@mycat src]# wget http://dl.mycat.io/1.6-RELEASE/Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz
[root@mycat src]# tar -xf Mycat-server-1.6-RELEASE-20161028204710-linux.tar.gz
[root@mycat src]# cd mycat/
[root@mycat mycat]# ll
drwxr-xr-x. 2 root root 190 Jul 12 08:50 bin drwxrwxrwx. 2 root root 6 Feb 29 2016 catlet drwxrwxrwx. 4 root root 4096 Jul 12 08:50 conf drwxr-xr-x. 2 root root 4096 Jul 12 08:50 lib drwxrwxrwx. 2 root root 6 Oct 28 2016 logs -rwxrwxrwx. 1 root root 217 Oct 28 2016 version.txt
1.3 配置mycat
[root@mycat mycat]# cd conf/
[root@mycat conf]# ll
-rwxrwxrwx. 1 root root 88 Oct 28 2016 autopartition-long.txt -rwxrwxrwx. 1 root root 48 Oct 28 2016 auto-sharding-long.txt -rwxrwxrwx. 1 root root 62 Oct 28 2016 auto-sharding-rang-mod.txt -rwxrwxrwx. 1 root root 334 Oct 28 2016 cacheservice.properties -rwxrwxrwx. 1 root root 439 Oct 28 2016 ehcache.xml -rwxrwxrwx. 1 root root 2132 Oct 28 2016 index_to_charset.properties -rwxrwxrwx. 1 root root 1246 Oct 10 2016 log4j2.xml -rwxrwxrwx. 1 root root 178 Oct 28 2016 migrateTables.properties -rwxrwxrwx. 1 root root 246 Oct 28 2016 myid.properties -rwxrwxrwx. 1 root root 15 Oct 28 2016 partition-hash-int.txt -rwxrwxrwx. 1 root root 102 Oct 28 2016 partition-range-mod.txt -rwxrwxrwx. 1 root root 4794 Oct 28 2016 rule.xml -rwxrwxrwx. 1 root root 4219 Oct 28 2016 schema.xml #主要配置這個文件 -rwxrwxrwx. 1 root root 413 Oct 28 2016 sequence_conf.properties -rwxrwxrwx. 1 root root 75 Oct 28 2016 sequence_db_conf.properties -rwxrwxrwx. 1 root root 27 Oct 28 2016 sequence_distributed_conf.properties -rwxrwxrwx. 1 root root 51 Oct 28 2016 sequence_time_conf.properties -rwxrwxrwx. 1 root root 3717 Oct 28 2016 server.xml -rwxrwxrwx. 1 root root 16 Oct 28 2016 sharding-by-enum.txt -rwxrwxrwx. 1 root root 4182 Oct 28 2016 wrapper.conf drwxrwxrwx. 2 root root 4096 Jul 12 08:50 zkconf drwxrwxrwx. 2 root root 36 Jul 12 08:50 zkdownload
[root@mycat conf]# cat schema.xml
<?xml version="1.0"?> <!DOCTYPE mycat:schema SYSTEM "schema.dtd"> <mycat:schema xmlns:mycat="http://io.mycat/"> <!‐‐ TESTDB 表示mycat 的邏輯數據庫名稱當schema 節點沒有子節點table 的時候，一定要有dataNode 屬性存在‐‐> <schema name="TESTDB" checkSQLschema="false" sqlMaxLimit="100" dataNode="dn1"> </schema> <dataNode name="dn1" dataHost="localhost1" database="master1" /> <dataHost name="localhost1" 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="hostM1" url="192.168.132.121:3306" user="root" password="123456"> <!-- can have multi read hosts --> <readHost host="hostS2" url="192.168.132.122:3306" user="root" password="123456" /> </writeHost> </dataHost> </mycat:schema>
注意 dataHost 節點的下面三個屬性balance， switchType， writeType
balance="0", 不開啟讀寫分離機制，所有讀操作都發送到當前可用的writeHost 上。
balance="1"，全部的readHost 與stand by writeHost 參與select語句的負載均衡，簡單的說，當雙主雙從模式(M1‐>S1，M2‐>S2，並且M1 與M2 互為主備)，正常情況下，M2,S1,S2都參與select 語句的負載均衡。
balance="2"，所有讀操作都隨機的在writeHost、readhost 上分發。
balance="3"，所有讀請求隨機的分發到writeHost 下的readhost 執行，writeHost 不負擔讀壓力
writeType 表示寫模式
writeType="0"，所有的操作發送到配置的第一個writehost
writeType="1"，隨機發送到配置的所有writehost
writeType="2"，不執行寫操作
switchType 指的是切換的模式，目前的取值也有4 種：
switchType=‘‐1‘ 表示不自動切換
switchType=‘1‘ 默認值，表示自動切換
switchType=‘2‘ 基於MySQL 主從同步的狀態決定是否切換,心跳語句為show slave status
switchType=‘3‘基於MySQL galary cluster 的切換機制（適合集群）（1.4.1），心跳語句為show status like ‘wsrep%‘。
配置端口，用戶名
[root@mycat conf]# vim 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="useSqlStat">0</property> <!-- 1為開啟實時統計、0為關閉 --> <property name="useGlobleTableCheck">0</property> <!-- 1為開啟全加班一致性檢測、0為關閉 --> <property name="sequnceHandlerType">2</property> <!-- <property name="useCompression">1</property>--> <!--1為開啟mysql壓縮協議--> <!-- <property name="fakeMySQLVersion">5.6.20</property>--> <!--設置模擬的MySQL版本號--> <!-- <property name="processorBufferChunk">40960</property> --> <!-- <property name="processors">1</property> <property name="processorExecutor">32</property> --> <!--默認為type 0: DirectByteBufferPool | type 1 ByteBufferArena--> <property name="processorBufferPoolType">0</property> <!--默認是65535 64K 用於sql解析時最大文本長度 --> <!--<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="handleDistributedTransactions">0</property> <!-- off heap for merge/order/group/limit 1開啟 0關閉 --> <property name="useOffHeapForMerge">1</property> <!-- 單位為m --> <property name="memoryPageSize">1m</property> <!-- 單位為k --> <property name="spillsFileBufferSize">1k</property> <property name="useStreamOutput">0</property> <!-- 單位為m --> <property name="systemReserveMemorySize">384m</property> <!--是否采用zookeeper協調切換 --> <property name="useZKSwitch">true</property> </system> <!-- 全局SQL防火牆設置 --> <!-- <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="root"> <property name="password">123456</property> <property name="schemas">TESTDB</property> <!-- 表級 DML 權限設置 --> <!-- <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">TESTDB</property> <property name="readOnly">true</property> </user> </mycat:server
二 驗證
2.1 啟動Mycat
[root@mycat conf]# ../bin/mycat start
2.2 日志
[root@mycat conf]# cat /usr/local/src/mycat/logs/wrapper.log
STATUS | wrapper | 2019/07/12 10:44:55 | --> Wrapper Started as Daemon STATUS | wrapper | 2019/07/12 10:44:55 | Launching a JVM... ERROR | wrapper | 2019/07/12 10:45:12 | Unable to start JVM: No such file or directory (2) #沒有JVM，安裝java ERROR | wrapper | 2019/07/12 10:45:12 | JVM exited while loading the application. FATAL | wrapper | 2019/07/12 10:45:12 | There were 5 failed launches in a row, each lasting less than 300 seconds. Giving up. FATAL | wrapper | 2019/07/12 10:45:12 | There may be a configuration problem: please check the logs. STATUS | wrapper | 2019/07/12 10:45:12 | <-- Wrapper Stopped
[root@mycat conf]# yum -y install java
[root@mycat conf]# ../bin/mycat start
[root@mycat conf]# tail -f /usr/local/src/mycat/logs/wrapper.log
INFO | jvm 1 | 2019/07/12 11:02:46 | 2019-07-12 11:02:46,389 [INFO ][$_NIOREACTOR-0-RW] connectionAcquired MySQLConnection [id=12, lastTime=1562943766373, user=root, schema=master1, old shema=master1, borrowed=false, fromSlaveDB=true, threadId=1428, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=192.168.132.122, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false] (io.mycat.backend.mysql.nio.handler.NewConnectionRespHandler:NewConnectionRespHandler.java:45) INFO | jvm 1 | 2019/07/12 11:02:46 | MyCAT Server startup successfully. see logs in logs/mycat.log
2.3 連接，端口為8066
[root@mycat ~]# mysql -uroot -p1234567 -h192.168.132.125 -P8066
MySQL [(none)]> show databases;
+----------+
| DATABASE |
+----------+
| TESTDB |
+----------+
2.4 寫入數據測試
MySQL [(none)]> use TESTDB; MySQL [TESTDB]> show tables; MySQL [TESTDB]> select * from test; MySQL [TESTDB]> insert into test values (555); MySQL [TESTDB]> select * from test; +------+ | id | +------+ | 1 | | 2 | | 2 | | 2 | | 11 | | 12 | | 111 | | 222 | | 333 | | 444 | | 555 | +------+ mater查看 mysql> select * from master1.test; +------+ | id | +------+ | 1 | | 2 | | 2 | | 2 | | 11 | | 12 | | 111 | | 222 | | 333 | | 444 | | 555 | +------+ slave查看 mysql> select * from master1.test; +------+ | id | +------+ | 1 | | 2 | | 2 | | 2 | | 11 | | 12 | | 111 | | 222 | | 333 | | 444 | | 555 | +------+
成功寫入數據
2.5 驗證讀寫分離
修改日志級別為debug
[root@mycat conf]# vim log4j2.xml
<Loggers>
<!--<AsyncLogger name="io.mycat" level="info" includeLocation="true" additivity="false">-->
<!--<AppenderRef ref="Console"/>-->
<!--<AppenderRef ref="RollingFile"/>-->
<!--</AsyncLogger>-->
<asyncRoot level="debug" includeLocation="true">
<AppenderRef ref="Console" />
<AppenderRef ref="RollingFile"/>
</asyncRoot>
</Loggers>
[root@mycat conf]# /usr/local/src/mycat/bin/mycat stop
[root@mycat conf]# /usr/local/src/mycat/bin/mycat start
寫入一個數據
MySQL [TESTDB]> insert into test values (666);
[root@mycat conf]# tail -f /usr/local/src/mycat/logs/wrapper.log
INFO | jvm 1 | 2019/07/12 11:15:06 | 2019-07-12 11:15:06,662 [DEBUG][$_NIOREACTOR-0-RW] con need syn ,total syn cmd 1 commands SET names utf8;schema change:false con:MySQLConnection [id=7, lastTime=1562944506662, user=root, schema=master1, old shema=master1, borrowed=true, fromSlaveDB=false, threadId=14906, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{insert into test values (666)}, respHandler=SingleNodeHandler [node=dn1{insert into test values (666)}, packetId=0], host=192.168.132.121, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=true] (io.mycat.backend.mysql.nio.MySQLConnection:MySQLConnection.java:448) INFO | jvm 1 | 2019/07/12 11:15:06 | 2019-07-12 11:15:06,668 [DEBUG][$_NIOREACTOR-1-RW] release connection MySQLConnection [id=7, lastTime=1562944506646, user=root, schema=master1, old shema=master1, borrowed=true, fromSlaveDB=false, threadId=14906, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{insert into test values (666)}, respHandler=SingleNodeHandler [node=dn1{insert into test values (666)}, packetId=1], host=192.168.132.121, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=true] (io.mycat.server.NonBlockingSession:NonBlockingSession.java:341) INFO | jvm 1 | 2019/07/12 11:15:06 | 2019-07-12 11:15:06,669 [DEBUG][$_NIOREACTOR-1-RW] release channel MySQLConnection [id=7, lastTime=1562944506646, user=root, schema=master1, old shema=master1, borrowed=true, fromSlaveDB=false, threadId=14906, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=192.168.132.121, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false] (io.mycat.backend.datasource.PhysicalDatasource:PhysicalDatasource.java:442) INFO | jvm 1 | 2019/07/12 11:15:14 | 2019-07-12 11:15:13,968 [DEBUG][Timer1] con query sql:select user() to con:MySQLConnection [id=3, lastTime=1562944513968, user=root, schema=master1, old shema=master1, borrowed=true, fromSlaveDB=false, threadId=14907, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=192.168.132.121, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false] (io.mycat.sqlengine.SQLJob:SQLJob.java:88)
發現在192.168.132.121 主數據庫上面
查找數據
MySQL [TESTDB]> select * from test;
INFO | jvm 1 | 2019/07/12 11:20:13 | 2019-07-12 11:20:13,419 [DEBUG][$_NIOREACTOR-0-RW] con need syn ,total syn cmd 1 commands SET names utf8;schema change:false con:MySQLConnection [id=15, lastTime=1562944813419, user=root, schema=master1, old shema=master1, borrowed=true, fromSlaveDB=true, threadId=1596, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{select * from test}, respHandler=SingleNodeHandler [node=dn1{select * from test}, packetId=0], host=192.168.132.122, port=3306, statusSync=null, writeQueue=0, modifiedSQLExecuted=false] (io.mycat.backend.mysql.nio.MySQLConnection:MySQLConnection.java:448) INFO | jvm 1 | 2019/07/12 11:20:13 | 2019-07-12 11:20:13,421 [DEBUG][$_NIOREACTOR-0-RW] release connection MySQLConnection [id=15, lastTime=1562944813407, user=root, schema=master1, old shema=master1, borrowed=true, fromSlaveDB=true, threadId=1596, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{select * from test}, respHandler=SingleNodeHandler [node=dn1{select * from test}, packetId=16], host=192.168.132.122, port=3306, statusSync=io.mycat.backend.mysql.nio.MySQLConnection$StatusSync@3055d901, writeQueue=0, modifiedSQLExecuted=false] (io.mycat.server.NonBlockingSession:NonBlockingSession.java:341)
在salve192.168.132.122從數據庫上面，讀和寫在不同的服務器上面
2.6 問題
但這種方式有個問題，即master 掛了以后，slave 也不能提供讀和寫服務Slave 掛了 不能查詢，但是可以插入。
停掉主數據庫
[root@master1 ~]# systemctl stop mysqld
[root@mycat ~]# mysql -uroot -p1234567 -h192.168.132.125 -P8066 TESTDB
MySQL [TESTDB]> select * from test; ERROR 1184 (HY000): Connection refused MySQL [TESTDB]> insert into test values (777); ERROR 1184 (HY000): Connection refused
已經不能查詢，也不可以插入
停掉slave
不可以查，但是可以寫
[root@slave ~]# systemctl stop mysqld
MySQL [TESTDB]> select * from test; ERROR 1184 (HY000): Connection refused MySQL [TESTDB]> insert into test values (777); Query OK, 1 row affected (0.00 sec)
讀寫分離配置完成
這種結構過於簡單，但是實現了讀寫分離的功能，生產中需要綜合考慮單點故障的問題，需要更可靠的架構！