Mycat实战之离散分片

1 枚举分片（customer表）

1.1 修改配置信息加载配置文件

<tableRule name="sharding-by-intfile">
        <rule>
                <columns>datanode</columns>
                <algorithm>hash-int</algorithm>
        </rule>
</tableRule>

vi partition-hash-int.txt
db1=0
db2=1
[root@mysqldb conf]#

1.2 insert演示路由信息以及mycat日志

mysql> insert into customer(id,customer_id,datanode) values(2,2,'db2');
Query OK, 1 row affected (0.00 sec)

mysql> explain insert into customer(id,customer_id,datanode) values(1,1,'db1');
+-----------+-----------------------------------------------------------------+
| DATA_NODE | SQL                                                             |
+-----------+-----------------------------------------------------------------+
| dn1       | insert into customer(id,customer_id,datanode) values(1,1,'db1') |
+-----------+-----------------------------------------------------------------+
1 row in set (0.00 sec)

查看mycat日志

1.3 查询路由信息以及mycat日志

mysql> explain select * from customer where datanode='db1';
+-----------+---------------------------------------------------------+
| DATA_NODE | SQL                                                     |
+-----------+---------------------------------------------------------+
| dn1       | SELECT * FROM customer WHERE datanode = 'db1' LIMIT 100 |
+-----------+---------------------------------------------------------+
1 row in set (0.00 sec)

mysql> select * from customer where datanode='db1';
+----+-------------+----------+
| id | customer_id | datanode |
+----+-------------+----------+
|  1 |           1 | db1      |
+----+-------------+----------+
1 row in set (0.01 sec)

mycat日志路由信息

2 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。
此方法为直接根据字符子串（必须是数字）计算分区号（由应用传递参数，显式指定分区号）。

2.1 修改配置文件

vi rule.xml
<function name="sharding-by-substring" 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>

<tableRule name="sharding-by-substring">
        <rule> <columns>id</columns>
                <algorithm>sharding-by-substring</algorithm>
        </rule>
</tableRule>

vi schema.xml
#增加tablerule
<table name="mycatbysubstring" primaryKey="ID" dataNode="dn1,dn2,dn3" rule="sharding-by-substring"/>

#加载配置文件
reload @@config

2.2 创建表 插入数据

 create table mycatbysubstring (id  varchar(64) not null  primary key,create_time datetime,datanode varchar(10))

 insert into mycatbysubstring (id,create_time,datanode) values('0-10000000','2017-06-25',database());
 insert into mycatbysubstring (id,create_time,datanode) values('1-10000000','2017-06-25',database());

针对插入语句，分析mycat.log日志

2.3 查询语句 分片字段是等值运算,分析mycat.log

mysql>  select * from mycatbysubstring where id='1-10000000';
+------------+---------------------+----------+
| id         | create_time         | datanode |
+------------+---------------------+----------+
| 1-10000000 | 2017-06-25 00:00:00 | db2      |
+------------+---------------------+----------+
1 row in set (0.06 sec)

mysql> explain  select * from mycatbysubstring where id='1-10000000';
+-----------+------------------------------------------------------+
| DATA_NODE | SQL                                                  |
+-----------+------------------------------------------------------+
| dn2       | select * from mycatbysubstring where id='1-10000000' |
+-----------+------------------------------------------------------+
1 row in set (0.00 sec)

分析mycat.log日志

2.4 查询语句:like查询，查询也是所有dbn上,分析mycat.log

mysql> explain select * from mycatbysubstring where id like '1%';
+-----------+-------------------------------------------------------------+
| DATA_NODE | SQL                                                         |
+-----------+-------------------------------------------------------------+
| dn1       | SELECT * FROM mycatbysubstring WHERE id LIKE '1%' LIMIT 100 |
| dn2       | SELECT * FROM mycatbysubstring WHERE id LIKE '1%' LIMIT 100 |
| dn3       | SELECT * FROM mycatbysubstring WHERE id LIKE '1%' LIMIT 100 |
+-----------+-------------------------------------------------------------+
3 rows in set (0.02 sec)

分析mycat.log日志