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, [email protected]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>