1。程序指定分区的分片
此规则是在运行阶段有应用自主决定路由到那个分片。
此方法为直接依据字符子串（必须是数字）计算分区号（由应用传递參数。显式指定分区号）。
2，加入配置文件
在function.xml里面进行配置：
<function name="sharding-by-substring-040302" class="org.opencloudb.route.function.PartitionDirectBySubString">
<property name="startIndex">0</property>
<property name="size">1</property>
<property name="partitionCount">8</property>
<property name="defaultPartition">0</property>
</function>
比如id=0-100000020在此配置中代表依据id中从startIndex=0，開始，截取siz=1位数字即0，0就是获取的分区，假设没传默认分配到defaultPartition
<tableRule name="tr-sharding-substr-mc040302">
<rule>
<columns>CODE</columns>
<algorithm>sharding-by-substring-040302</algorithm>
</rule>
</tableRule>在schema.xml里面进行配置：
<table name="ORDER040302" primaryKey="ID" dataNode="dn21,dn22" rule="tr-sharding-substr-mc040302"/>3，建表而且录入数据
CREATE TABLE ORDER040302(ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,CODE VARCHAR(64),SN VARCHAR(64),CREATE_TIME DATETIME);
mysql> CREATE TABLE ORDER040302(ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,CODE VARCHAR(64),SN VARCHAR(64),CREATE_TIME DATETIME);
Query OK, 0 rows affected (0.05 sec)
mysql>
INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(1,'0-10000020','beijing_03-10000020',NOW());
INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW());
mysql> explain INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(1,'0-10000020','beijing_03-10000020',NOW());
+-----------+----------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+----------------------------------------------------------------------------------------------------+
| dn21 | INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(1,'0-10000020','beijing_03-10000020',NOW()) |
+-----------+----------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql>
mysql> INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(1,'0-10000020','beijing_03-10000020',NOW());
Query OK, 1 row affected (0.01 sec)
mysql>
mysql> explain INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW());
+-----------+-----------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-----------------------------------------------------------------------------------------------------+
| dn22 | INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW()) |
+-----------+-----------------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW());
Query OK, 1 row affected (0.00 sec)
mysql> 4，对insert操作流程进行分析，參考mycat.log对路由过程做完整的分析
查看后台mycat.log分析例如以下：
開始获取连接：
02/13 00:40:18.173 DEBUG [$_NIOREACTOR-1-RW] (ServerQueryHandler.java:56) -ServerConnection [id=1, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW())
開始路由匹配：
02/13 00:40:18.175 DEBUG [$_NIOREACTOR-1-RW] (NonBlockingSession.java:113) -ServerConnection [id=1, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW()), route={
1 -> dn22{INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW())}
匹配好路由后，直接往相应的dn21节点開始运行insert数据录入操作：
02/13 00:40:18.180 DEBUG [$_NIOREACTOR-1-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=17, lastTime=1455295218162, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=199, charset=latin1, txIsolation=3, autocommit=true, attachment=dn22{INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW())}, respHandler=SingleNodeHandler [node=dn22{INSERT INTO ORDER040302(ID,CODE,SN,CREATE_TIME) VALUES(2,'1-10000020','shanghai_10-10000020',NOW())}, packetId=0], host=10.254.1.11, port=3327, statusSync=null, writeQueue=0, modifiedSQLExecuted=true]
连接释放：
02/13 00:40:18.180 DEBUG [$_NIOREACTOR-1-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=17, lastTime=1455295218162, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=199, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=10.254.1.11, port=3327, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]
02/13 00:40:24.390 DEBUG [Timer1] (SQLJob.java:85) -con query s5，运行简单的查询，假设指定分片字段ID字段，则走分片查询单个分片节点
mycat命令台显示结果：
mysql> explain select * from ORDER040302 t1 where CODE= '0-10000020';
+-----------+------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+------------------------------------------------------------------+
| dn21 | SELECT * FROM ORDER040302 t1 WHERE CODE = '0-10000020' LIMIT 100 |
+-----------+------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> select * from ORDER040302 t1 where CODE= '0-10000020';
+----+------------+---------------------+---------------------+
| ID | CODE | SN | CREATE_TIME |
+----+------------+---------------------+---------------------+
| 1 | 0-10000020 | beijing_03-10000020 | 2016-02-13 00:40:27 |
+----+------------+---------------------+---------------------+
1 row in set (0.01 sec)
mysql>查看后台mycat日志信息：
02/13 00:44:46.717 DEBUG [$_NIOREACTOR-1-RW] (ServerQueryHandler.java:56) -ServerConnection [id=1, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]explain select * from ORDER040302 t1 where CODE= '0-10000020'
02/13 00:44:46.718 DEBUG [$_NIOREACTOR-1-RW] (EnchachePool.java:76) -SQLRouteCache miss cache ,key:TESTDB select * from ORDER040302 t1 where CODE= '0-10000020'
02/13 00:44:46.719 DEBUG [$_NIOREACTOR-1-RW] (EnchachePool.java:59) -SQLRouteCache add cache ,key:TESTDB select * from ORDER040302 t1 where CODE= '0-10000020' value:select * from ORDER040302 t1 where CODE= '0-10000020', route={
1 -> dn21{SELECT *
FROM ORDER040302 t1
WHERE CODE = '0-10000020'
LIMIT 100}
}6。假设分片字段范围的查询，则走全部节点去检索。哪怕仅仅有一条数据在一个分片上。route路由也是走全部的分片进行检索查询
mysql> explain select * from ORDER040302 t1 where CODE likt '0-1%';
+-----------+---------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------+
| dn21 | SELECT * FROM ORDER040302 t1 WHERE CODE LIMIT 100 |
| dn22 | SELECT * FROM ORDER040302 t1 WHERE CODE LIMIT 100 |
+-----------+---------------------------------------------------+
2 rows in set (0.00 sec)
mysql> 7，假设不走分片字段的查询。即使是单个数据。也要route路由全部的分片，走全部的分片进行查询
mysql> explain select * from ORDER040302 t1 where SN='beijing_03-10000020';
+-----------+-------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-------------------------------------------------------------------------+
| dn21 | SELECT * FROM ORDER040302 t1 WHERE SN = 'beijing_03-10000020' LIMIT 100 |
| dn22 | SELECT * FROM ORDER040302 t1 WHERE SN = 'beijing_03-10000020' LIMIT 100 |
+-----------+-------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql>