By Valleylord

更新日期:

文章目录
  1. 1. MyCAT select 日志分析
  2. 2. 动态加载schema.xml
  3. 3. MyCAT 字符集

MyCAT 的日志还是相对比较简明的，看系统细节的话需要打开debug级别的 log，修改log4j.xml，

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<root>
  <level value="debug" />
  <appender-ref ref="FILE" />
   <!--<appender-ref ref="FILE" />-->
</root>

然后启动 MyCAT 就可以看到详细的日志了，日志默认路径在logs/mycat.log。启用之前，设置 Mysql 的字符集为 utf81，即修改/etc/mysql/my.cnf，在[mysqld]后添加character-set-server=utf8。

MyCAT select 日志分析

运行简单的查询 sql，如下，

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mysql> explain select * from travelrecord;
+-----------+--------------------------------------+
| DATA_NODE | SQL                                  |
+-----------+--------------------------------------+
| dn1       | SELECT * FROM travelrecord LIMIT 100 |
| dn2       | SELECT * FROM travelrecord LIMIT 100 |
| dn3       | SELECT * FROM travelrecord LIMIT 100 |
+-----------+--------------------------------------+
3 rows in set (0.25 sec)
mysql> select * from travelrecord;
+---------+---------+------------+------+------+
| id      | user_id | traveldate | fee  | days |
+---------+---------+------------+------+------+
| 1000000 | abc     | 2016-01-02 |  100 |    3 |
| 7000000 | abc     | 2016-01-02 |  100 |    3 |
+---------+---------+------------+------+------+
2 rows in set (0.09 sec)

对应的 debug 日志比较长，以下只列出了执行 select 的日志，explain 的日志没有列出，如下，

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01/23 15:33:33.441   INFO [$_NIOREACTOR-0-RW] (FrontendAuthenticator.java:193) -ServerConnection [id=1, schema=TESTDB, host=192.168.2.201, user=test,txIsolation=3, autocommit=true, schema=TESTDB]'test' login success
01/23 15:33:33.443  DEBUG [$_NIOREACTOR-0-RW] (ServerQueryHandler.java:56) -ServerConnection [id=1, schema=TESTDB, host=192.168.2.201, user=test,txIsolation=3, autocommit=true, schema=TESTDB]show databases
01/23 15:33:33.458  DEBUG [$_NIOREACTOR-0-RW] (ServerQueryHandler.java:56) -ServerConnection [id=1, schema=TESTDB, host=192.168.2.201, user=test,txIsolation=3, autocommit=true, schema=TESTDB]show tables
01/23 15:33:33.465  DEBUG [$_NIOREACTOR-0-RW] (ServerQueryHandler.java:56) -ServerConnection [id=1, schema=TESTDB, host=192.168.2.201, user=test,txIsolation=3, autocommit=true, schema=TESTDB]select * from travelrecord
01/23 15:33:33.469  DEBUG [$_NIOREACTOR-0-RW] (EnchachePool.java:76) -SQLRouteCache  miss cache ,key:TESTDBselect * from travelrecord
01/23 15:33:33.589  DEBUG [$_NIOREACTOR-0-RW] (EnchachePool.java:59) -SQLRouteCache add cache ,key:TESTDBselect * from travelrecord value:select * from travelrecord, route={
   1 -> dn1{SELECT *
FROM travelrecord
LIMIT 100}
   2 -> dn2{SELECT *
FROM travelrecord
LIMIT 100}
   3 -> dn3{SELECT *
FROM travelrecord
LIMIT 100}
}
01/23 15:33:33.589  DEBUG [$_NIOREACTOR-0-RW] (NonBlockingSession.java:113) -ServerConnection [id=1, schema=TESTDB, host=192.168.2.201, user=test,txIsolation=3, autocommit=true, schema=TESTDB]select * from travelrecord, route={
   1 -> dn1{SELECT *
FROM travelrecord
LIMIT 100}
   2 -> dn2{SELECT *
FROM travelrecord
LIMIT 100}
   3 -> dn3{SELECT *
FROM travelrecord
LIMIT 100}
} rrs 
01/23 15:33:33.593  DEBUG [$_NIOREACTOR-0-RW] (MultiNodeQueryHandler.java:82) -execute mutinode query select * from travelrecord
01/23 15:33:33.595  DEBUG [$_NIOREACTOR-0-RW] (MultiNodeQueryHandler.java:97) -has data merge logic 
01/23 15:33:33.595  DEBUG [$_NIOREACTOR-0-RW] (PhysicalDBPool.java:452) -select read source hostS1 for dataHost:localhost1
01/23 15:33:33.595  DEBUG [$_NIOREACTOR-0-RW] (MySQLConnection.java:445) -con need syn ,total syn cmd 1 commands SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;schema change:false con:MySQLConnection [id=2, lastTime=1453534413595, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=17, charset=utf8, txIsolation=0, autocommit=true, attachment=dn1{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.596  DEBUG [$_NIOREACTOR-0-RW] (PhysicalDBPool.java:452) -select read source hostS1 for dataHost:localhost1
01/23 15:33:33.597  DEBUG [$_NIOREACTOR-0-RW] (MySQLConnection.java:445) -con need syn ,total syn cmd 1 commands SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;schema change:false con:MySQLConnection [id=4, lastTime=1453534413597, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=16, charset=utf8, txIsolation=0, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.597  DEBUG [$_NIOREACTOR-0-RW] (PhysicalDBPool.java:452) -select read source hostS1 for dataHost:localhost1
01/23 15:33:33.597  DEBUG [$_NIOREACTOR-0-RW] (MySQLConnection.java:445) -con need syn ,total syn cmd 1 commands SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;schema change:false con:MySQLConnection [id=5, lastTime=1453534413597, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=12, charset=utf8, txIsolation=0, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.597  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=2, lastTime=1453534413593, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=17, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@3f164fd2, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.598  DEBUG [$_NIOREACTOR-1-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=5, lastTime=1453534413593, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=12, charset=utf8, txIsolation=3, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@94bf31, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.599  DEBUG [$_NIOREACTOR-1-RW] (MultiNodeQueryHandler.java:241) -on row end reseponse MySQLConnection [id=5, lastTime=1453534413593, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=12, charset=utf8, txIsolation=3, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@94bf31, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.598  DEBUG [$_NIOREACTOR-0-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=4, lastTime=1453534413593, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=16, charset=utf8, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@41a599fc, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.600  DEBUG [$_NIOREACTOR-1-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=5, lastTime=1453534413593, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=12, charset=utf8, txIsolation=3, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@94bf31, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.603  DEBUG [$_NIOREACTOR-1-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=5, lastTime=1453534413593, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=12, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.600  DEBUG [$_NIOREACTOR-2-RW] (DataMergeService.java:94) -field metadata inf:[DAYS=ColMeta [colIndex=4, colType=3], USER_ID=ColMeta [colIndex=1, colType=253], ID=ColMeta [colIndex=0, colType=8], TRAVELDATE=ColMeta [colIndex=2, colType=10], FEE=ColMeta [colIndex=3, colType=246]]
01/23 15:33:33.605  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:241) -on row end reseponse MySQLConnection [id=2, lastTime=1453534413593, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=17, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@3f164fd2, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.605  DEBUG [$_NIOREACTOR-2-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=2, lastTime=1453534413593, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=17, charset=utf8, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@3f164fd2, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.605  DEBUG [$_NIOREACTOR-2-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=2, lastTime=1453534413593, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=17, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.607  DEBUG [$_NIOREACTOR-0-RW] (MultiNodeQueryHandler.java:241) -on row end reseponse MySQLConnection [id=4, lastTime=1453534413593, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=16, charset=utf8, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@41a599fc, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.610  DEBUG [$_NIOREACTOR-0-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=4, lastTime=1453534413593, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=16, charset=utf8, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@17b029c7, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@41a599fc, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.610  DEBUG [$_NIOREACTOR-0-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=4, lastTime=1453534413593, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=16, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 15:33:33.611  DEBUG [BusinessExecutor5] (DataMergeService.java:296) -prepare mpp merge result for select * from travelrecord

以上日志中，执行过程如下，

  1. MyCAT 先收到 sql，然后去路径 cache 中查找是否已经有解析好的路径，但是没有找到，因此提示SQLRouteCache miss cache，于是解析该 sql，并将路径保存，提示SQLRouteCache add cache；
  2. 接下来，使用NonBlockingSession.java，即非阻塞会话来获取连接， 还有提示，使用MultiNodeQueryHandler，多节点查询，过程中需要数据合并，即has data merge logic；
  3. 然后，找到了读的数据源，提示select read source hostS1 for dataHost:localhost1，并提示获取连接成功，执行同步命令，-con need syn ,total syn cmd 1 commands，之后发送查询sql，因为 travelrecord 表在 db1、db2、db3 共有3个分片，因此，以上日志在这3个分片上各出现了一次；
  4. 然后，收到返回结果并调用回调函数，on row end reseponse，等数据接收完成还会提示received ok response，同样，也是收到3个分片上各一次；
  5. 执行完后，会释放 MyCAT 会话和 Mysql 连接，release connection MySQLConnection，release channel MySQLConnection；
  6. 收到的结果还需要显示列名，因此，上述执行过程中会提示，field metadata inf；
  7. 等收到3个分片的所有数据后，进行数据合并，prepare mpp merge result；

以上就是 MyCAT 上执行 sql 的基本步骤。

动态加载schema.xml

MyCAT 的schema.xml是可以动态加载（reload）的。假定新增一个分片表 T_VOTE (ID,PROVINCE)，PROVINCE 列用hash分片。首先需要修改rule.xml，

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<tableRule name="sharding-by-stringhash">
      <rule>
        <columns>province</columns>
        <algorithm>murmur</algorithm>
      </rule>
   </tableRule>

其中，murmur是一致性 hash 方法。在schema.xml中增加，

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<table name="t_vote" primaryKey="ID" dataNode="dn1,dn2,dn3" rule="sharding-by-stringhash" />

修改完文件后，使用管理端，端口9066，登陆MyCAT，用以下命令可以重新加载配置文件，

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mysql> reload @@config;
Query OK, 1 row affected (0.13 sec)
Reload config success

加载完成之后，可以发现用户端，即端口8066，上已经可以看到新增的 T_VOTE 表，

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mysql> show tables;
+------------------+
| Tables in TESTDB |
+------------------+
| company          |
| customer         |
| customer_addr    |
| employee         |
| goods            |
| hotnews          |
| orders           |
| order_items      |
| travelrecord     |
| t_vote           |
+------------------+
10 rows in set (0.00 sec)

查看这段时间内的日志，如下，

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01/23 16:43:14.003  DEBUG [$_NIOREACTOR-3-RW] (ManagerQueryHandler.java:65) -[thread=$_NIOREACTOR-3-RW,class=ManagerConnection,id=7,host=192.168.2.201,port=9066,schema=TESTDB]reload @@config
01/23 16:43:14.048   INFO [BusinessExecutor7] (CacheService.java:187) -clear all cache pool 
01/23 16:43:14.048   INFO [BusinessExecutor7] (EnchachePool.java:85) -clear cache ER_SQL2PARENTID
01/23 16:43:14.124   INFO [BusinessExecutor7] (EnchachePool.java:85) -clear cache SQLRouteCache
01/23 16:43:14.125   INFO [BusinessExecutor7] (DefaultLayedCachePool.java:100) -clear cache 
01/23 16:43:14.126   INFO [BusinessExecutor7] (EnchachePool.java:85) -clear cache TableID2DataNodeCache.TESTDB_ORDERS
01/23 16:43:14.128   WARN [BusinessExecutor6] (ReloadConfig.java:166) -send ok package to client [thread=BusinessExecutor6,class=ManagerConnection,id=7,host=192.168.2.201,port=9066,schema=TESTDB]
01/23 16:43:17.674  DEBUG [Timer0] (ConnectionHeartBeatHandler.java:52) -do heartbeat for con MySQLConnection [id=6, lastTime=1453538597657, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=15, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 16:43:17.675  DEBUG [Timer0] (ConnectionHeartBeatHandler.java:52) -do heartbeat for con MySQLConnection [id=4, lastTime=1453538597657, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=16, charset=utf8, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]

可以发现，重新加载的过程中，清理了一些 cache，并重新建立了心跳。

MyCAT 字符集

以上的实验中，MyCAT 的字符集和 Mysql 客户端的字符集都是采用 utf8，修改 Mysql 客户端的字符集为 latin1，即修改客户端所在机器的/etc/mysql/my.cnf，在[client]后添加default-character-set=latin1。再次执行相同的查询select * from travelrecord;，日志如下，

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01/23 17:30:17.877  DEBUG [$_NIOREACTOR-2-RW] (EnchachePool.java:70) -SQLRouteCache hit cache ,key:TESTDBselect * from travelrecord
01/23 17:30:17.877  DEBUG [$_NIOREACTOR-2-RW] (NonBlockingSession.java:113) -ServerConnection [id=4, schema=TESTDB, host=192.168.2.201, user=test,txIsolation=3, autocommit=true, schema=TESTDB]select * from travelrecord, route={
   1 -> dn1{SELECT *
FROM travelrecord
LIMIT 100}
   2 -> dn2{SELECT *
FROM travelrecord
LIMIT 100}
   3 -> dn3{SELECT *
FROM travelrecord
LIMIT 100}
} rrs 
01/23 17:30:17.877  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:82) -execute mutinode query select * from travelrecord
01/23 17:30:17.877  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:97) -has data merge logic 
01/23 17:30:17.877  DEBUG [$_NIOREACTOR-2-RW] (PhysicalDBPool.java:452) -select read source hostS1 for dataHost:localhost1
01/23 17:30:17.878  DEBUG [$_NIOREACTOR-2-RW] (PhysicalDBPool.java:452) -select read source hostS1 for dataHost:localhost1
01/23 17:30:17.878  DEBUG [$_NIOREACTOR-2-RW] (MySQLConnection.java:445) -con need syn ,total syn cmd 2 commands SET names latin1;SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;schema change:false con:MySQLConnection [id=100, lastTime=1453541417878, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=5, charset=latin1, txIsolation=0, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.878  DEBUG [$_NIOREACTOR-2-RW] (PhysicalDBPool.java:452) -select read source hostS1 for dataHost:localhost1
01/23 17:30:17.879  DEBUG [$_NIOREACTOR-2-RW] (MySQLConnection.java:445) -con need syn ,total syn cmd 2 commands SET names latin1;SET SESSION TRANSACTION ISOLATION LEVEL REPEATABLE READ;schema change:false con:MySQLConnection [id=99, lastTime=1453541417878, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=2, charset=latin1, txIsolation=0, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.879  DEBUG [$_NIOREACTOR-1-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=99, lastTime=1453541417860, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=2, charset=latin1, txIsolation=0, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@12bc7f96, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.879  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=100, lastTime=1453541417860, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=5, charset=latin1, txIsolation=0, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@327030f, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.880  DEBUG [$_NIOREACTOR-1-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=99, lastTime=1453541417860, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=2, charset=latin1, txIsolation=3, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@12bc7f96, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.880  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:171) -received ok response ,executeResponse:false from MySQLConnection [id=100, lastTime=1453541417860, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=5, charset=latin1, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@327030f, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.886  DEBUG [$_NIOREACTOR-1-RW] (DataMergeService.java:94) -field metadata inf:[DAYS=ColMeta [colIndex=4, colType=3], USER_ID=ColMeta [colIndex=1, colType=253], ID=ColMeta [colIndex=0, colType=8], TRAVELDATE=ColMeta [colIndex=2, colType=10], FEE=ColMeta [colIndex=3, colType=246]]
01/23 17:30:17.887  DEBUG [$_NIOREACTOR-1-RW] (MultiNodeQueryHandler.java:241) -on row end reseponse MySQLConnection [id=99, lastTime=1453541417860, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=2, charset=latin1, txIsolation=3, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@12bc7f96, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.887  DEBUG [$_NIOREACTOR-1-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=99, lastTime=1453541417860, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=2, charset=latin1, txIsolation=3, autocommit=true, attachment=dn3{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@12bc7f96, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.888  DEBUG [$_NIOREACTOR-1-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=99, lastTime=1453541417860, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=2, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.888  DEBUG [$_NIOREACTOR-3-RW] (MultiNodeQueryHandler.java:241) -on row end reseponse MySQLConnection [id=101, lastTime=1453541417860, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=3, charset=latin1, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.888  DEBUG [$_NIOREACTOR-2-RW] (MultiNodeQueryHandler.java:241) -on row end reseponse MySQLConnection [id=100, lastTime=1453541417860, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=5, charset=latin1, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@327030f, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.889  DEBUG [$_NIOREACTOR-2-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=100, lastTime=1453541417860, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=5, charset=latin1, txIsolation=3, autocommit=true, attachment=dn2{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@327030f, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.889  DEBUG [$_NIOREACTOR-2-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=100, lastTime=1453541417860, user=root, schema=db2, old shema=db2, borrowed=true, fromSlaveDB=false, threadId=5, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.889  DEBUG [$_NIOREACTOR-3-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=101, lastTime=1453541417860, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=3, charset=latin1, txIsolation=3, autocommit=true, attachment=dn1{SELECT *
FROM travelrecord
LIMIT 100}, respHandler=org.opencloudb.mysql.nio.handler.MultiNodeQueryHandler@41d3a141, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.890  DEBUG [$_NIOREACTOR-3-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=101, lastTime=1453541417860, user=root, schema=db1, old shema=db1, borrowed=true, fromSlaveDB=false, threadId=3, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=workstation, port=3316, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
01/23 17:30:17.891  DEBUG [BusinessExecutor3] (DataMergeService.java:296) -prepare mpp merge result for select * from travelrecord
01/23 17:30:17.892  DEBUG [BusinessExecutor3] (MultiNodeQueryHandler.java:324) -last packet id:10

可以发现，日志差异并不大，只是所有原先是charset=utf8的地方换成了charset=latin1，还有一处重要的变化是执行同步命令con need syn ,total syn cmd 2 commands，多了一个命令SET names latin1用于设置字符集。不过这样做是有问题的，客户端与服务器端的字符集不同，会导致乱码。例如，有中文的情况，如下图，

  1. http://blog.csdn.net/sin90lzc/article/details/7648439↩

文章目录
  1. 1. MyCAT select 日志分析
  2. 2. 动态加载schema.xml
  3. 3. MyCAT 字符集

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