Mycat之——枚举分片

原创

冰河技术 2017-08-11 12:48:40 ©著作权

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一、简单描述

今天，我们就一起来看下Mycat中的枚举分片，所谓的枚举分片，就是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，具体使用场景可根据自己具体的业务场景确定。

二、实现枚举分片

1、配置rule.xml

在rule.xml添加如下配置：

<!-- 
    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-customer" 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-customer">
     <rule>
         <columns>province</columns>
         <algorithm>hash-int-customer</algorithm>
    </rule>
</tableRule>

2、创建partition-hash-int.txt文件

内容如下：

10000=0 
10010=1

3、配置schema.xml

<?xml version="1.0"?>
<!DOCTYPE mycat:schema SYSTEM "schema.dtd">
<mycat:schema xmlns:mycat="http://org.opencloudb/" >

	<schema name="lyzdb" checkSQLschema="false" sqlMaxLimit="100">
		<!-- global table is auto cloned to all defined data nodes ,so can join 
			with any table whose sharding node is in the same data node -->
		<table name="t_order" primaryKey="id" dataNode="dn1,dn2" rule="tr-hash-int-customer"/>
	</schema>
	<!-- <dataNode name="dn1$0-743" dataHost="localhost1" database="db$0-743" 
		/> -->
	<dataNode name="dn1" dataHost="localhost1" database="db1" />
	<dataNode name="dn2" dataHost="localhost1" database="db2" />
	<!--<dataNode name="dn4" dataHost="sequoiadb1" database="SAMPLE" />
	 <dataNode name="jdbc_dn1" dataHost="jdbchost" database="db1" /> 
	<dataNode	name="jdbc_dn2" dataHost="jdbchost" database="db2" /> 
	<dataNode name="jdbc_dn3" 	dataHost="jdbchost" database="db3" /> -->
	<dataHost name="localhost1" maxCon="1000" minCon="10" balance="0"
		writeType="0" dbType="mysql" dbDriver="native" switchType="1"  slaveThreshold="100">
		<heartbeat>select user()</heartbeat>
		<!-- can have multi write hosts -->
		<writeHost host="hostM1" url="192.168.209.137:3306" user="root" password="root"></writeHost>
		<!--<writeHost host="hostS1" url="localhost:3316" user="root"-->
			<!--password="123456" />-->
		<!-- <writeHost host="hostM2" url="localhost:3316" user="root" password="123456"/> -->
	</dataHost>
</mycat:schema>

至此，Mycat的配置工作就完成了，下面我们就一起来测试下Mycat的枚举分片功能。

三、测试

1、建表并且录入数据

mysql> explain CREATE TABLE t_order (ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME);
+-----------+--------------------------------------------------------------------------------------------------------------------+
| DATA_NODE | SQL                                                                                                                |
+-----------+--------------------------------------------------------------------------------------------------------------------+
| dn1       | CREATE TABLE t_order (ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME) |
| dn2       | CREATE TABLE t_order (ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME) |
+-----------+--------------------------------------------------------------------------------------------------------------------+
2 rows in set (0.09 sec)

mysql>
mysql> CREATE TABLE t_order (ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME);
Query OK, 0 rows affected (0.19 sec)

mysql> explain INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10001_10000',NOW());
+-----------+----------------------------------------------------------------------------------------------+
| DATA_NODE | SQL                                                                                          |
+-----------+----------------------------------------------------------------------------------------------+
| dn1       | INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10001_10000',NOW()) |
+-----------+----------------------------------------------------------------------------------------------+
1 row in set (0.07 sec)

mysql> INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10001_10000',NOW());
Query OK, 1 row affected (0.11 sec)

mysql> explain INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'tianjin_10010',NOW());
+-----------+----------------------------------------------------------------------------------------+
| DATA_NODE | SQL                                                                                    |
+-----------+----------------------------------------------------------------------------------------+
| dn2       | INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'tianjin_10010',NOW()) |
+-----------+----------------------------------------------------------------------------------------+
1 row in set (0.00 sec)

mysql> INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'tianjin_10010',NOW());
Query OK, 1 row affected (0.04 sec)

Mycat日志如下：

NCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME), route={
   1 -> dn1{CREATE TABLE t_order (ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME)}
   2 -> dn2{CREATE TABLE t_order (ID INT NOT NULL AUTO_INCREMENT PRIMARY KEY,PROVINCE INT,SN VARCHAR(64),CREATE_TIME DATETIME)}
} rrs 
08/10 13:38:09.330  DEBUG [$_NIOREACTOR-0-RW] (NonBlockingSession.java:113) -ServerConnection [id=1, schema=lyzdb, host=192.168.209.1, user=lyz,txIsolation=3, autocommit=true, schema=lyzdb]INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10001_10000',NOW()), route={
   1 -> dn1{INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(1,10000,'beijing_10001_10000',NOW())}
} rrs 
08/10 13:39:45.878  DEBUG [$_NIOREACTOR-0-RW] (NonBlockingSession.java:113) -ServerConnection [id=1, schema=lyzdb, host=192.168.209.1, user=lyz,txIsolation=3, autocommit=true, schema=lyzdb]INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'tianjin_10010',NOW()), route={
   1 -> dn2{INSERT INTO t_order (ID,PROVINCE,SN,CREATE_TIME) VALUES(2,10010,'tianjin_10010',NOW())}
} rrs

由此可见，创建表的时候，Mycat是将SQL路由到所有的数据节点；录入数据的时候，是根据分片字段将数据路由到指定的数据分片节点；

2、按照分片字段查询

mysql> explain select * from t_order where PROVINCE=10000;
+-----------+--------------------------------------------------------+
| DATA_NODE | SQL                                                    |
+-----------+--------------------------------------------------------+
| dn1       | SELECT * FROM t_order WHERE PROVINCE = 10000 LIMIT 100 |
+-----------+--------------------------------------------------------+
1 row in set (0.40 sec)

Mycat日志如下：

08/10 13:42:02.586  DEBUG [$_NIOREACTOR-0-RW] (EnchachePool.java:76) -SQLRouteCache  miss cache ,key:lyzdb select * from t_order where PROVINCE=10000
08/10 13:42:02.987  DEBUG [$_NIOREACTOR-0-RW] (EnchachePool.java:59) -SQLRouteCache add cache ,key:lyzdb select * from t_order where PROVINCE=10000 value:select * from t_order where PROVINCE=10000, route={
   1 -> dn1{SELECT *
FROM t_order
WHERE PROVINCE = 10000
LIMIT 100}
}

由此可见，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

3、按照分片字段范围查询

mysql> explain select * from t_order where PROVINCE >= 10000;
+-----------+---------------------------------------------------------+
| DATA_NODE | SQL                                                     |
+-----------+---------------------------------------------------------+
| dn1       | SELECT * FROM t_order WHERE PROVINCE >= 10000 LIMIT 100 |
| dn2       | SELECT * FROM t_order WHERE PROVINCE >= 10000 LIMIT 100 |
+-----------+---------------------------------------------------------+
2 rows in set (0.00 sec)

Mycat日志如下：

08/10 13:43:07.238  DEBUG [$_NIOREACTOR-0-RW] (EnchachePool.java:59) -SQLRouteCache add cache ,key:lyzdb select * from t_order where PROVINCE >= 10000 value:select * from t_order where PROVINCE >= 10000, route={
   1 -> dn1{SELECT *
FROM t_order
WHERE PROVINCE >= 10000
LIMIT 100}
   2 -> dn2{SELECT *
FROM t_order
WHERE PROVINCE >= 10000
LIMIT 100}
}

由此可见，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

4、按照非分片字段查询

mysql> explain select * from t_order where sn = 'tianjin_10010';
+-----------+------------------------------------------------------------+
| DATA_NODE | SQL                                                        |
+-----------+------------------------------------------------------------+
| dn1       | SELECT * FROM t_order WHERE sn = 'tianjin_10010' LIMIT 100 |
| dn2       | SELECT * FROM t_order WHERE sn = 'tianjin_10010' LIMIT 100 |
+-----------+------------------------------------------------------------+
2 rows in set (0.00 sec)

Mycat日志如下：

08/10 13:45:01.416  DEBUG [$_NIOREACTOR-0-RW] (EnchachePool.java:59) -SQLRouteCache add cache ,key:lyzdb select * from t_order where sn = 'tianjin_10010' value:select * from t_order where sn = 'tianjin_10010', route={
   1 -> dn1{SELECT *
FROM t_order
WHERE sn = 'tianjin_10010'
LIMIT 100}
   2 -> dn2{SELECT *
FROM t_order
WHERE sn = 'tianjin_10010'
LIMIT 100}
}

由此可见，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