使用Mycat實現MySQL的分庫分表、讀寫分離、主從切換
阿新 • • 發佈:2018-05-08
Mycat 分庫分表 讀寫分離 主從切換 Mycat及MySQL實例部署情況:
Mycat:
IP:10.20.8.57,Port:3310/3311
MySQL :
db1-M1,IP:10.20.8.126,Port:3306
db1-M2,IP:10.20.8.126,Port:3307
db2-M1,IP:10.25.80.7,Port:3307
架構圖如下:
Mycat:
IP:10.20.8.57,Port:3310/3311
MySQL :
db1-M1,IP:10.20.8.126,Port:3306
db1-M2,IP:10.20.8.126,Port:3307
db2-M1,IP:10.25.80.7,Port:3307
架構圖如下:
配置Mycat
server.xml:
<!DOCTYPE mycat:server SYSTEM "server.dtd"> <mycat:server xmlns:mycat="http://io.mycat/"> <system> <property name="useSqlStat">1</property> <property name="useGlobleTableCheck">0</property> <property name="defaultSqlParser">druidparser</property> <property name="sequnceHandlerType">2</property> <property name="processorBufferPoolType">0</property> <property name="serverPort">3310</property> <!-- mycat的使用端口 --> <property name="managerPort">3311</property> <!-- mycat的管理端口 --> <property name="handleDistributedTransactions">0</property> <property name="useOffHeapForMerge">1</property> <property name="memoryPageSize">1m</property> <property name="spillsFileBufferSize">1k</property> <property name="useStreamOutput">0</property> <property name="systemReserveMemorySize">389m</property> </system> <user name="root"> <property name="password">123456</property> <property name="schemas">db</property> <property name="readOnly">false</property> </user> </mycat:server>
schema.xml:
<?xml version="1.0"?> <!DOCTYPE mycat:schema SYSTEM "schema.dtd"> <mycat:schema xmlns:mycat="http://io.mycat/"> <!-- 數據庫配置,與server.xml中的數據庫對應 --> <schema name="db" checkSQLschema="false" sqlMaxLimit="100"> <table name="t1" dataNode="dn1,dn2" rule="mod-long" /> <!-- 對2取模,詳見rule.xml --> </schema> <!-- 分片配置 --> <dataNode name="dn1" dataHost="shard1" database="db1" /> <dataNode name="dn2" dataHost="shard2" database="db2" /> <!-- 物理數據庫配置 --> <dataHost name="shard1" maxCon="1000" minCon="10" balance="3" writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100"> <heartbeat>select user();</heartbeat> <writeHost host="db1-M1" url="10.20.8.126:3306" user="root" password="123456"> <readHost host="db1-M2" url="10.20.8.126:3307" user="root" password="123456" /> </writeHost> <!-- 配置standby writeHost --> <writeHost host="db1-M2" url="10.20.8.126:3307" user="root" password="123456"> </writeHost> </dataHost> <dataHost name="shard2" maxCon="1000" minCon="10" balance="0" writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100"> <heartbeat>select user();</heartbeat> <writeHost host="db2-M1" url="10.25.80.7:3307" user="root" password="123456"> </writeHost> </dataHost> </mycat:schema>
修改rule.xml中下列配置項:
<tableRule name="mod-long"> <rule> <columns>id</columns> <!-- t1的分片列 --> <algorithm>mod-long</algorithm> </rule> </tableRule> <function name="mod-long" class="io.mycat.route.function.PartitionByMod"> <!-- how many data nodes --> <property name="count">2</property> <!-- count值與分片個數相同 --> </function>
配置文件中各標簽的含義可參考文章:MyCat關鍵配置說明
啟動Mycat:
[root@SZB-L0059021 bin]# ./mycat start
Starting Mycat-server...
[root@SZB-L0059021 bin]# ./mycat status
Mycat-server is running (27020).
[root@SZB-L0059021 bin]# mysql -uroot -p123456 -Ddb -h127.0.0.1 -P3310
分庫分表驗證:
mysql> show tables;
+--------------+
| Tables in db |
+--------------+
| t1 |
+--------------+
1 row in set (0.00 sec)
mysql> desc t1;
+---------+-------------+------+-----+---------+-------+
| Field | Type | Null | Key | Default | Extra |
+---------+-------------+------+-----+---------+-------+
| id | int(11) | YES | | NULL | |
| db_name | varchar(20) | YES | | NULL | |
+---------+-------------+------+-----+---------+-------+
2 rows in set (0.01 sec)
mysql> insert into t1(id,db_name) values(1,database());
Query OK, 1 row affected (0.01 sec)
mysql> insert into t1(id,db_name) values(2,database());
Query OK, 1 row affected (0.03 sec)
mysql> select * from t1;
+------+---------+
| id | db_name |
+------+---------+
| 2 | db1 | --id=2,對2取模為0,所以插入dn1
| 1 | db2 | --id=1,對2取模為1,所以插入dn2
+------+---------+
2 rows in set (0.01 sec)
上述查詢結果可知,兩次插入的數據分落入了db1、db2上,實現了分庫
讀寫分離驗證:
mysql> select * from t1;
+------+---------+
| id | db_name |
+------+---------+
| 2 | db1 | --來自shard1上的db1-M2
| 1 | db2 | --來自shard2上的db2-M1
+------+---------+
2 rows in set (0.01 sec)
查看日誌可知,上述查詢結果來自dn1中db1-M2(端口3307)和dn2中的db2-M1:
2018-05-08 15:03:39.385 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.server.NonBlockingSession.execute(NonBlockingSession.java:110)) - ServerConnection [id=1, schema=db, host=127.0.0.1, user=root,txIsolation=3, autocommit=true, schema=db]select * from t1, route={
1 -> dn1{SELECT *
FROM t1
LIMIT 100}
2 -> dn2{SELECT *
FROM t1
LIMIT 100}
}
...
2018-05-08 15:03:39.391 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler.rowEofResponse(MultiNodeQueryHandler.java:311)) - on row end reseponse MySQLConnection [id=29, lastTime=1525763019368, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=true, threadId=511, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM t1
LIMIT 100}, respHandler=io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler@66328ec4, host=10.20.8.126, port=3307, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
...
2018-05-08 15:03:39.392 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler.rowEofResponse(MultiNodeQueryHandler.java:311)) - on row end reseponse MySQLConnection [id=3, lastTime=1525763019387, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=28, charset=utf8, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM t1
LIMIT 100}, respHandler=io.mycat.backend.mysql.nio.handler.MultiNodeQueryHandler@66328ec4, host=10.25.80.7, port=3307, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
...
主從切換:
通過查看mycat/conf目錄下的dnindex.properties文件,可以知道mycat正在使用的writeHost,0表示schema.xml中dataHost標簽下的第一個writeHost。
[root@SZB-L0059021 conf]# cat dnindex.properties
#update
#Tue May 08 12:59:24 CST 2018
shard2=0
shard1=0 --此時狀態正常,mycat選取每個dataHost標簽中的第一個writeHost作為寫入入口
切換至10.20.8.126主機,並手動停掉db1-M1
10.20.8.126:3306:Master > mysqladmin -uroot -p123456 shutdown
回到10.20.8.57(mycat主機),再次查看dnindex.properties
[root@SZB-L0059021 conf]# cat dnindex.properties
#update
#Tue May 08 15:12:12 CST 2018
shard2=0
shard1=1 --db1-M1被shutdown後,mycat在shard1上的writeHost切換至db1-M2
切換至10.20.8.57(mycat所在主機),執行下述insert命令
mysql> insert into t1(id,db_name) values(4,database());
Query OK, 1 row affected (0.01 sec)
查看日誌可知,Mycat此時選擇通過db1-M2(端口3307)寫入數據:
2018-05-08 15:13:44.987 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.server.NonBlockingSession.releaseConnection(NonBlockingSession.java:341)) - release connection MySQLConnection [id=24, lastTime=1525763624968, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=506, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{insert into t1(id,db_name) values(4,database())}, respHandler=SingleNodeHandler [node=dn1{insert into t1(id,db_name) values(4,database())}, packetId=1], host=10.20.8.126, port=3307, statusSync=null, writeQueue=0, modifiedSQLExecuted=true]
由於dataHost中配置了writeType="0",所以即使db1-M1重啟恢復後,Mycat仍然會選擇db1-M2作為shard1的
writeHost。
驗證:
切換至10.20.8.126主機,並手動啟動db1-M1
10.20.8.126:3306:Master > mysqld_safe &
在Mycat中插入驗證數據
mysql> insert into t1(id,db_name) values(6,database());
Query OK, 1 row affected (0.02 sec)
查看日誌可知,數據仍通過db1-M2(端口3307)寫入:
2018-05-08 15:16:09.579 DEBUG [$_NIOREACTOR-0-RW] (io.mycat.server.NonBlockingSession.releaseConnection(NonBlockingSession.java:341)) - release connection MySQLConnection [id=32, lastTime=1525763769548, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=514, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{insert into t1(id,db_name) values(6,database())}, respHandler=SingleNodeHandler [node=dn1{insert into t1(id,db_name) values(6,database())}, packetId=1], host=10.20.8.126, port=3307, statusSync=null, writeQueue=0, modifiedSQLExecuted=true]
此時要想讓Mycat在shard1上的writeHost重新變為db1-M1,只需修改dnindex.properties中的shard1=1為shard1=0,並重啟Mycat即可。
使用Mycat實現MySQL的分庫分表、讀寫分離、主從切換