mycat 离散分片 -> 枚举分片
1，枚举分片
枚举分片：通过在配置文件中配置可能的枚举id，自己配置分片，本规则适用于特定的场景，比如有些业务需要按照省份或区县来做保存，而全国省份区县固定的
2，添加配置文件
在function.xml里面进行配置：
<!-- mapFile标识配置文件名称 type默认值为0（0表示Integer，非零表示String） 默认节点的作用：枚举分片时，如果碰到不识别的枚举值，就让它路由到默认节点 -->
<function name="hash-int-mc040301" class="org.opencloudb.route.function.PartitionByFileMap">
<property name="mapFile">partition-hash-int.txt</property>
<property name="defaultNode">0</property>
<property name="type">0</property>
</function>
<tableRule name="tr-hash-int-mc040301">
<rule>
<columns>PROVINCE</columns>
<algorithm>hash-int-mc040301</algorithm>
</rule>
</tableRule>在schema.xml里面进行配置：
<table name="ORDER040301" primaryKey="ID" dataNode="dn21,dn22" rule="tr-hash-int-mc040301"/>autopartition-long04.txt文件的配置, 10000代表北京分片到第一个节点，10010代表上海分片到第二个节点
[root@crm_1_21 conf]# more partition-hash-int04.txt
10000=0
10010=1
[root@crm_1_21 conf]# 注意： 此配置非常简单，即预先制定可能的id范围到某个分片，所有的节点配置都是从0开始，及0代表节点1
3，建表并且录入数据
CREATE TABLE ORDER040301(ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME);
mysql> CREATE TABLE ORDER040301(ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME);
Query OK, 0 rows affected (0.05 sec)
mysql>
INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10006_10000',NOW());
INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW());
mysql> explain INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10006_10000',NOW());
+-----------+-------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-------------------------------------------------------------------------------------------------+
| dn21 | INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10006_10000',NOW()) |
+-----------+-------------------------------------------------------------------------------------------------+
1 row in set (0.12 sec)
mysql> INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10006_10000',NOW());
Query OK, 1 row affected (0.02 sec)
mysql>
mysql> explain INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW());
+-----------+--------------------------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+--------------------------------------------------------------------------------------------+
| dn22 | INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW()) |
+-----------+--------------------------------------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW());
Query OK, 1 row affected (0.00 sec)
mysql> 4，对insert操作流程进行分析，参考mycat.log对路由过程做完整的分析
查看后台mycat.log分析如下：
开始获取连接：
02/12 23:32:11.323 DEBUG [$_NIOREACTOR-2-RW] (ServerQueryHandler.java:56) -ServerConnection [id=2, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW()) 开始路由匹配： 02/12 23:32:11.324 DEBUG [$_NIOREACTOR-2-RW] (NonBlockingSession.java:113) -ServerConnection [id=2, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW()), route={ 1 -> dn22{INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW())} } rrs 匹配好路由后，直接往对应的dn21节点开始执行insert数据录入操作： 02/12 23:32:11.327 DEBUG [$_NIOREACTOR-0-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=16, lastTime=1455291131321, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=153, charset=latin1, txIsolation=3, autocommit=true, attachment=dn22{INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW())}, respHandler=SingleNodeHandler [node=dn22{INSERT INTO ORDER040301(ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'shanghai_10010',NOW())}, packetId=0], host=13.123.1.11, port=3327, statusSync=null, writeQueue=0, modifiedSQLExecuted=true] 连接释放： 02/12 23:32:11.328 DEBUG [$_NIOREACTOR-0-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=16, lastTime=1455291131321, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=153, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=13.123.1.11, port=3327, statusSync=null, writeQueue=0, modifiedSQLExecuted=false]5，执行简单的查询，如果指定分片字段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 ORDER040301 t1 where PROVINCE=10000;
+-----------+---------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------------------+
| dn21 | SELECT * FROM ORDER040301 t1 WHERE PROVINCE = 10000 LIMIT 100 |
+-----------+---------------------------------------------------------------+
1 row in set (0.00 sec)
mysql> select * from ORDER040301 t1 where PROVINCE=10000;
+----+----------+---------------------+---------------------+
| ID | PROVINCE | SN | CREATE_TIME |
+----+----------+---------------------+---------------------+
| 1 | 10000 | beijing_10006_10000 | 2016-02-12 23:31:55 |
+----+----------+---------------------+---------------------+
1 row in set (0.01 sec)
mysql> 查看后台mycat日志信息：
02/12 23:36:08.302 DEBUG [$_NIOREACTOR-2-RW] (ServerQueryHandler.java:56) -ServerConnection [id=2, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]select * from ORDER040301 t1 where PROVINCE=10000 02/12 23:36:08.303 DEBUG [$_NIOREACTOR-2-RW] (EnchachePool.java:76) -SQLRouteCache miss cache ,key:TESTDBselect * from ORDER040301 t1 where PROVINCE=10000 02/12 23:36:08.304 DEBUG [$_NIOREACTOR-2-RW] (EnchachePool.java:59) -SQLRouteCache add cache ,key:TESTDBselect * from ORDER040301 t1 where PROVINCE=10000 value:select * from ORDER040301 t1 where PROVINCE=10000, route={ 1 -> dn21{SELECT * FROM ORDER040301 t1 WHERE PROVINCE = 10000 LIMIT 100} } 02/12 23:36:08.305 DEBUG [$_NIOREACTOR-2-RW] (NonBlockingSession.java:113) -ServerConnection [id=2, schema=TESTDB, host=127.0.0.1, user=test,txIsolation=3, autocommit=true, schema=TESTDB]select * from ORDER040301 t1 where PROVINCE=10000, route={ 1 -> dn21{SELECT * FROM ORDER040301 t1 WHERE PROVINCE = 10000 LIMIT 100} } rrs 02/12 23:36:08.305 DEBUG [$_NIOREACTOR-2-RW] (PhysicalDBPool.java:452) -select read source hostM2 for dataHost:m1 02/12 23:36:08.307 DEBUG [$_NIOREACTOR-1-RW] (NonBlockingSession.java:229) -release connection MySQLConnection [id=5, lastTime=1455291368304, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=161, charset=latin1, txIsolation=3, autocommit=true, attachment=dn21{SELECT * FROM ORDER040301 t1 WHERE PROVINCE = 10000 LIMIT 100}, respHandler=SingleNodeHandler [node=dn21{SELECT * FROM ORDER040301 t1 WHERE PROVINCE = 10000 LIMIT 100}, packetId=7], host=13.123.1.11, port=3317, statusSync=org.opencloudb.mysql.nio.MySQLConnection$StatusSync@1cfa73be, writeQueue=0, modifiedSQLExecuted=false] 02/12 23:36:08.308 DEBUG [$_NIOREACTOR-1-RW] (PhysicalDatasource.java:403) -release channel MySQLConnection [id=5, lastTime=1455291368304, user=root, schema=db3, old shema=db3, borrowed=true, fromSlaveDB=false, threadId=161, charset=latin1, txIsolation=3, autocommit=true, attachment=null, respHandler=null, host=13.123.1.11, port=3317, statusSync=null, writeQueue=0, modifiedSQLExecuted=false] 6，如果分片字段范围的查询，则走所有节点去检索，哪怕只有一条数据在一个分片上，route路由也是走所有的分片进行检索查询
mysql> explain select * from ORDER040301 t1 where SN='beijing_10006_10000';
+-----------+-------------------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+-------------------------------------------------------------------------+
| dn21 | SELECT * FROM ORDER040301 t1 WHERE SN = 'beijing_10006_10000' LIMIT 100 |
| dn22 | SELECT * FROM ORDER040301 t1 WHERE SN = 'beijing_10006_10000' LIMIT 100 |
+-----------+-------------------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql>
mysql> select * from ORDER040301 t1 where SN='beijing_10006_10000';
+----+----------+---------------------+---------------------+
| ID | PROVINCE | SN | CREATE_TIME |
+----+----------+---------------------+---------------------+
| 1 | 10000 | beijing_10006_10000 | 2016-02-12 23:31:55 |
+----+----------+---------------------+---------------------+
1 row in set (0.01 sec)
mysql> 7，如果不走分片字段的查询，即使是单个数据，也要route路由所有的分片，走所有的分片进行查询
mysql> explain select * from ORDER040301 t1 where PROVINCE < 10010;
+-----------+---------------------------------------------------------------+
| DATA_NODE | SQL |
+-----------+---------------------------------------------------------------+
| dn21 | SELECT * FROM ORDER040301 t1 WHERE PROVINCE < 10010 LIMIT 100 |
| dn22 | SELECT * FROM ORDER040301 t1 WHERE PROVINCE < 10010 LIMIT 100 |
+-----------+---------------------------------------------------------------+
2 rows in set (0.00 sec)
mysql> select * from ORDER040301 t1 where PROVINCE < 10010;
+----+----------+---------------------+---------------------+
| ID | PROVINCE | SN | CREATE_TIME |
+----+----------+---------------------+---------------------+
| 1 | 10000 | beijing_10006_10000 | 2016-02-12 23:31:55 |
+----+----------+---------------------+---------------------+
1 row in set (0.01 sec)
mysql>