MyCat水平分库

Posted 2021-03-31 架构师学习路线

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一.什么是水平分库

将一张表水平切分到多个库中

1.1分片原则

1.需要分片的表是少数的
2.能不切分尽量不要切分
3.日志表可以采取归档方式
4.选择合适的切分规则和分片建，确保数据分片均匀，否则依然存在性能瓶颈
5.尽量避免跨分片join操作，保证关联操作表在同一分片

1.2分片后如何处理查询

1.根据简单分片规则，对分片键进行路由到正确的后端物理数据库
2.如果不是使用分片键的话，将会遍历后端数据库，极大消耗性能

二.水平切分步骤

2.1根据业务状态确定要进行水平切分的表

读写频繁，访问量非常大的表才需要切分，一般是订单表

如何选择分片键

1.尽可能的比较均匀分布数据到各个节点上，自增长主键并不是很好的选择，因为不会用于查询
2.业务字段是最频繁的或者最重要的查询条件

2.2分析业务模型选择分片键及分片算法

一般分片键选择的是频繁作为查询的字段，关键是能保证分片后的数据分布均匀，常用简单取模算法

对订单相关表进行水平切分
不仅仅是订单表，经常与订单表关联查询的表也需要一并分片，避免跨分片查询，大表不适合作为全局表
订单号，可以保证分片均匀，但是实际业务很少根据订单号来查询
下单人ID，业务查询更多，更适合，但是分片并不均匀，但不严重，值得考虑
采用简单取模分片算法，可以保证数据尽可能均匀

2.3适用mycat部署分片集群

1.使用schema.xml配置逻辑库及逻辑表

<!-- <table name="order_master" primaryKey="order_id" dataNode="dn_orderdb" /> -->
	<table name="order_master" primaryKey="order_id" dataNode="dn_orderdb01,dn_orderdb02,dn_orderdb03,dn_orderdb04" rule="order_master"/>
<!-- 只需要增加表所在的物理节点schema名称和指定规则rule -->

<dataNode name="dn_orderdb01" dataHost="mysql10143" database="orderdb01" />
<dataNode name="dn_orderdb02" dataHost="mysql10143" database="orderdb02" />
<dataNode name="dn_orderdb03" dataHost="mysql10144" database="orderdb03" />
<dataNode name="dn_orderdb04" dataHost="mysql10144" database="orderdb04" />

2.使用rule.xml配置分片表的分片规则

    <tableRule name="order_master">
        <rule>
            <columns>customer_id</columns>
            <algorithm>mod-long</algorithm>
        </rule>
    </tableRule>
    <function name="mod-long" class="org.opencloudb.route.function.PartitionByMod">
    <!-- 分片算法，唯一；JAVA类路径，1.6是"io.mycat.route.function.PartitionByMod"-->
        <property name="count">4</property>
    </function>

3.验证

# 现在逻辑库上进行查看，此时是没有数据的
# 需要提前建库建表，否则报错表不存在
app_imooc@172.16.10.142 00:26:  [imooc_db]> select * from order_master;
Empty set (0.08 sec)

# 在逻辑库imooc_db上插入5条数据，正常是orderdb02 2条数据（节点索引顺序为1），其他各1条数据
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70005,90005,'yzw5',5,5,5,'address1',1,20);

# truncate table报错
app_imooc@172.16.10.142 10:51:  [imooc_db]> truncate table order_master;
ERROR 1105 (HY000): DROP command denied to user 'bm_mycat'@'172.16.10.142' for table 'order_master'

# 逻辑库查看插入结果
app_imooc@172.16.10.142 10:50:  [imooc_db]> select order_id,order_sn,customer_id from order_master;
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|    80005 |    70002 |       90002 |
|    80005 |    70003 |       90003 |
|    80005 |    70004 |       90004 |
|    80006 |    70001 |       90001 |
|    80007 |    70005 |       90005 |
+----------+----------+-------------+
5 rows in set (0.00 sec)

# 在物理库查看是否有这4条数据，验证成功
root@localhost 10:52:  [orderdb01]> select order_id,order_sn,customer_id from order_master;
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|    80005 |    70004 |       90004 |
+----------+----------+-------------+
1 row in set (0.00 sec)

root@localhost 10:52:  [orderdb02]> select order_id,order_sn,customer_id from order_master;
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|    80006 |    70001 |       90001 |
|    80007 |    70005 |       90005 |
+----------+----------+-------------+
2 rows in set (0.00 sec)

root@localhost 10:05:  [orderdb03]> select order_id,order_sn,customer_id from order_master;

+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|    80005 |    70002 |       90002 |
+----------+----------+-------------+
1 row in set (0.00 sec)

root@localhost 10:52:  [orderdb04]> select order_id,order_sn,customer_id from order_master;
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|    80005 |    70003 |       90003 |
+----------+----------+-------------+
1 row in set (0.00 sec)

4.使用server.xml配置访问权限

#配置用户登录

2.4测试分片集群，采用应用端双写方式进行

2.5业务及数据迁移

三.全局自增ID

分片表中的自增ID在逻辑表中有重复
第三方给ID或者使用mycat自增ID

3.1全局自增ID方法

1.本地文件方式：适用服务器本地磁盘的方式
2.数据库方式：适用数据库存储的方式
3.本地时间戳方式：适用时间戳
4.分布式zookeeper生成ID

3.2本地文件全局ID

优点：本地加载，读取速度快，配置简单
缺点：集群部署无法使用，不同的mycat无法保证id唯一，使mycat变成了有状态的中间件

配置方法

1.server.xml增加属性

<property name="sequnceHandlerType>0</property>

2.sequence_conf.properties配置

#default global sequence
GLOBAL.HISIDS=
GLOBAL.MINID=10001
GLOBAL.MAXID=20000
GLOBAL.CURID=10000

# self define sequence
ORDER_MASTER.HISIDS=
ORDER_MASTER.MINID=1001
ORDER_MASTER.MAXID=2000
ORDER_MASTER.CURID=1000


# 以上配置文件中，自定义表名必须大写书写HISIDS：表示使用过的历史分段(一般无特殊需要可不配置)
# MINID ：最小ID 值
# MAXID ：表示最大ID 值
# CURID ：表示当前ID 值。
# 当 sequence_conf.properties的配置名字与 表名一致的时候sql可以不包含ID字段（此处表名为id_local_file），逻辑表需要增加属性autoIncrement="true"

3.插入数据

# mycat restart
# delete from order_master;
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70005,90005,'yzw5',5,5,5,'address1',1,20);
# 此时逻辑表中的order_id唯一
app_imooc@172.16.10.142 11:35:  [imooc_db]> select order_id,order_sn,customer_id from order_master;                                                                                            
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|    10004 |    70004 |       90004 |
|    10003 |    70003 |       90003 |
|    10001 |    70001 |       90001 |
|    10005 |    70005 |       90005 |
|    10002 |    70002 |       90002 |
+----------+----------+-------------+
5 rows in set (0.01 sec)

insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70005,90005,'yzw5',5,5,5,'address1',1,20);

# 此时逻辑表中的order_id依然是唯一，但是ID值使用的是自定义表自增属性的值
app_imooc@172.16.10.142 11:48:  [imooc_db]> select order_id,order_sn,customer_id from order_master;
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|     1009 |    70003 |       90003 |
|     1008 |    70002 |       90002 |
|     1007 |    70001 |       90001 |
|     1011 |    70005 |       90005 |
|     1010 |    70004 |       90004 |
+----------+----------+-------------+
5 rows in set (0.00 sec)
# 不指定自增字段插入
# 逻辑表必须增加自增属性，否则不指定自增字段插入则使用分片表本身自增id
#<table name="order_master" primaryKey="order_id" autoIncrement="true" dataNode="dn_orderdb01,dn_orderdb02,dn_orderdb03,dn_orderdb04" rule="order_master"/>
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70005,90005,'yzw5',5,5,5,'address1',1,20);

app_imooc@172.16.10.142 11:58:  [imooc_db]> select order_id,order_sn,customer_id from order_master;                                                                                            
+----------+----------+-------------+
| order_id | order_sn | customer_id |
+----------+----------+-------------+
|     1001 |    70001 |       90001 |
|     1005 |    70005 |       90005 |
|     1003 |    70003 |       90003 |
|     1004 |    70004 |       90004 |
|     1002 |    70002 |       90002 |
+----------+----------+-------------+
5 rows in set (0.01 sec)

3.3数据库方式

优点：mycat重启后，sequence值不会被初始化，因为从数据库中取，每次取完按自增步长增加
缺点：sequence数据库主从切换后，存在mycat适用缓存序列号，可能存在ID重复风险，可以手动增加步长避免

配置方法

1.server.xml增加属性

<property name="sequnceHandlerType">1</property>

2.sequence_db_conf.properties

#sequence stored in datanode
GLOBAL=dn_test
ORDER_MASTER=dn_test
datanode必须要mycat能访问的数据库，并不一定需要在分片表的数据库中

3.schema.xml增加主机节点和数据节点，让mycat能访问上面配置的数据节点
4.在对应节点的数据库中增加函数和表，用户必须授予表、函数、存储过程的访问权限

# 需要全局ID的表明需要写入表中，大写
INSERT INTO mycat_sequence values('ORDER_MASTER', 1, 100);
root@master 11:48:  [test]> select * from mycat_sequence;
+--------------+---------------+-----------+
| NAME         | current_value | increment |
+--------------+---------------+-----------+
| GLOBAL       |        100000 |       100 |
| ORDER_MASTER |             1 |       100 |
+--------------+---------------+-----------+
2 rows in set (0.00 sec)

5.schema.xml增加配置，适用全局自增IDautoIncrement="true"

<table name="order_master" primaryKey="order_id" autoIncrement="true" dataNode="dn_orderdb01,dn_orderdb02,dn_orderdb03,dn_orderdb04" rule="order_master"/>

6.在逻辑库中插入数据

# 适用ID表里面的全局ID插入
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70005,90005,'yzw5',5,5,5,'address1',1,20);
# 使用ID表里面的对应表ID插入
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70005,90005,'yzw5',5,5,5,'address1',1,20);
# 不指定id列，效果同上
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70005,90005,'yzw5',5,5,5,'address1',1,20);

3.4本地时间戳方式

ID= 64 位二进制 (42(毫秒)+5(机器 ID)+5(业务编码)+12(重复累加)

优点：与mycat无关，跟时间有关系
缺点：字段最大长度必须大于等于18，int无法满足

配置方法

1.server.xml增加属性

<property name="sequnceHandlerType">2</property>

2.sequence_time_conf.properties

#sequence depend on TIME
WORKID=01
DATAACENTERID=01

# 0-31任意整数

3.在对应节点的数据库中增加函数和表，用户必须授予表、函数、存储过程的访问权限

# 需要全局ID的表明需要写入表中，大写
INSERT INTO mycat_sequence values('ORDER_MASTER', 1, 100);
root@master 11:48:  [test]> select * from mycat_sequence;
+--------------+---------------+-----------+
| NAME         | current_value | increment |
+--------------+---------------+-----------+
| GLOBAL       |        100000 |       100 |
| ORDER_MASTER |             1 |       100 |
+--------------+---------------+-----------+
2 rows in set (0.00 sec)

5.schema.xml增加配置，适用全局自增IDautoIncrement="true"

<table name="order_master" primaryKey="order_id" autoIncrement="true" dataNode="dn_orderdb01,dn_orderdb02,dn_orderdb03,dn_orderdb04" rule="order_master"/>

6.在逻辑库中插入数据

# int无法满足
ERROR 1264 (22003): Out of range value for column 'order_id' at row 

app_imooc@172.16.10.142 12:32:  [imooc_db]> select next value for MYCATSEQ_ORDER_MASTER;
+---------------------+
| 1025962766269288448 |
+---------------------+
| 1025962766269288448 |
+---------------------+
1 row in set (0.00 sec)

app_imooc@172.16.10.142 12:32:  [imooc_db]> select next value for MYCATSEQ_GLOBAL;
+---------------------+
| 1025962827724230656 |
+---------------------+
| 1025962827724230656 |
+---------------------+
1 row in set (0.00 sec)
1
# 适用ID表里面的全局ID插入
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_GLOBAL,70005,90005,'yzw5',5,5,5,'address1',1,20);
# 使用ID表里面的对应表ID插入
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_id,order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(next value for MYCATSEQ_ORDER_MASTER,70005,90005,'yzw5',5,5,5,'address1',1,20);
# 不指定id列，效果同上
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70005,90005,'yzw5',5,5,5,'address1',1,20);

select order_id,order_sn,customer_id from order_master;

3.5分布式zookeeper生成ID 未测试，1.5没有默认配置文件

基于ZK 与本地配置的分布式ID 生成器(可以通过ZK 获取集群（机房）唯一InstanceID，也可以通过配置文件配置InstanceID)ID 结构：long 64 位，ID 最大可占63 位
current time millis(微秒时间戳38 位,可以使用17 年)
instanceId（实例ID，可以通过ZK 或者配置文件获取，5 位，也就是十进制0-31）
threadId（线程ID，9 位）
increment(自增,6 位)
一共63 位，可以承受单机房单机器单线程1000*(2^6)=640000 的并发。

优点：无悲观锁，无强竞争，吞吐量更高
缺点：对zookeeper集群的要求增加。

配置方法

1.server.xml增加属性

<property name="sequnceHandlerType">3</property>

2.sequence_distributed_conf.properties

INSTANCEID=01
CLUSTERID=01

3.在对应节点的数据库中增加函数和表，用户必须授予表、函数、存储过程的访问权限

# 需要全局ID的表明需要写入表中，大写
INSERT INTO mycat_sequence values('ORDER_MASTER', 1, 100);
root@master 11:48:  [test]> select * from mycat_sequence;
+--------------+---------------+-----------+
| NAME         | current_value | increment |
+--------------+---------------+-----------+
| GLOBAL       |        100000 |       100 |
| ORDER_MASTER |             1 |       100 |
+--------------+---------------+-----------+
2 rows in set (0.00 sec)

5.schema.xml增加配置，适用全局自增IDautoIncrement="true"

<table name="order_master" primaryKey="order_id" autoIncrement="true" dataNode="dn_orderdb01,dn_orderdb02,dn_orderdb03,dn_orderdb04" rule="order_master"/>

6.在逻辑库中插入数据

四.ER关系

跨分片查询存在跨节点问题

app_imooc@172.16.10.142 13:55:  [imooc_db]> select * from order_master m join order_detail o on m.order_id=o.order_id;
ERROR 1064 (HY000): invalid route in sql, multi tables found but datanode has no intersection  sql:select * from order_master m join order_detail o on m.order_id=o.order_id

根据ER关系，也需要对order_detail这张表进行分片

4.1配置步骤

1.在原先order_master所在4个分配数据库(orderdb01/02/03/04)中建立order_detail表结构

CREATE TABLE `order_detail` (
  `order_detail_id` int(10) unsigned NOT NULL AUTO_INCREMENT COMMENT '自增主键ID,订单详情表ID',
  `order_id` int(10) unsigned NOT NULL COMMENT '订单表ID',
  `product_id` int(10) unsigned NOT NULL COMMENT '订单商品ID',
  `product_name` varchar(50) NOT NULL COMMENT '商品名称',
  `product_cnt` int(11) NOT NULL DEFAULT '1' COMMENT '购买商品数量',
  `product_price` decimal(8,2) NOT NULL COMMENT '购买商品单价',
  `average_cost` decimal(8,2) NOT NULL DEFAULT '0.00' COMMENT '平均成本价格',
  `weight` float DEFAULT NULL COMMENT '商品重量',
  `fee_money` decimal(8,2) NOT NULL DEFAULT '0.00' COMMENT '优惠分摊金额',
  `w_id` int(10) unsigned NOT NULL COMMENT '仓库ID',
  `modified_time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP ON UPDATE CURRENT_TIMESTAMP COMMENT '最后修改时间',
  PRIMARY KEY (`order_detail_id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 COMMENT='订单详情表';

2.schema.xml将全局分片表进行ER分片，在父表中增加子表信息

<table name="order_master" primaryKey="order_id" autoIncrement="true" dataNode="dn_orderdb01,dn_orderdb02,dn_orderdb03,dn_orderdb04" rule="order_master">
    <childTable name="order_detail" primaryKey="order_detail_id" joinKey="order_id" parentKey="order_id" autoIncrement="true" />
    <!-- 指定关联子表的表名、主键，及父表关联key、父表的主键，同时也需要指定全局ID -->
</table>

3.配置表order_detail全局自增ID(使用数据库方式)

# server.xml

# sequence_db_conf.properties增加order_detail自增ID
#sequence stored in datanode
GLOBAL=dn_test
ORDER_MASTER=dn_test
ORDER_DETAIL=dn_test
# 数据库中增加分片表信息
insert into mycat_sequence values('ORDER_DETAIL',1,1);

4.插入数据

# 先插入order_master
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70001,90001,'yzw1',1,1,1,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70002,90002,'yzw2',2,2,2,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70003,90003,'yzw3',3,3,3,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70004,90004,'yzw4',4,4,4,'address1',1,20);
insert into order_master(order_sn,customer_id,shipping_user,province,city,district,address,payment_method,order_money) values(70005,90005,'yzw5',5,5,5,'address1',1,20);
app_imooc@172.16.10.142 14:46:  [imooc_db]> select order_sn,customer_id,order_id from order_master;
+----------+-------------+----------+
| order_sn | customer_id | order_id |
+----------+-------------+----------+
|    70005 |       90005 |        5 |
|    70001 |       90001 |        6 |
|    70005 |       90005 |       10 |
|    70004 |       90004 |        4 |
|    70004 |       90004 |        9 |
|    70003 |       90003 |        3 |
|    70003 |       90003 |        8 |
|    70002 |       90002 |        2 |
|    70002 |       90002 |        7 |
+----------+-------------+----------+
9 rows in set (0.00 sec)

# 根据order_id插入order_detail
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,2,12,'商品2',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,3,13,'商品3',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,4,14,'商品4',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,5,15,'商品5',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,6,16,'商品6',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,7,17,'商品7',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,8,18,'商品8',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,9,19,'商品9',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,10,20,'商品10',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,5,21,'商品11',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,6,12,'商品2',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,8,12,'商品2',1,22.2,12,1,10,2);
insert into order_detail(order_detail_id,order_id,product_id,product_name,product_cnt,product_price,average_cost,weight,fee_money,w_id) values(next value for MYCATSEQ_ORDER_DETAIL,8,12,'商品2',1,22.2,12,1,10,2);

5.此时再进行分片关联查询验证数据

select m.order_id,o.order_detail_id,o.product_id,o.product_name from order_master m join order_detail o on m.order_id=o.order_id;
+----------+-----------------+------------+--------------+
| order_id | order_detail_id | product_id | product_name |
+----------+-----------------+------------+--------------+
|        3 |               4 |         13 | 商品3        |
|        8 |               9 |         18 | 商品8        |
|        8 |              14 |         12 | 商品2        |
|        8 |              15 |         12 | 商品2        |
|        2 |               3 |         12 | 商品2        |
|        7 |               8 |         17 | 商品7        |
|        4 |               5 |         14 | 商品4        |
|        9 |              10 |         19 | 商品9        |
|        5 |               6 |         15 | 商品5        |
|        6 |               7 |         16 | 商品6        |
|       10 |              11 |         20 | 商品10       |
|        5 |              12 |         21 | 商品11       |
|        6 |              13 |         12 | 商品2        |
+----------+-----------------+------------+--------------+
13 rows in set (0.00 sec)

6.在其中一个分片上可以验证，order_id一致的表落在同一个分片

root@localhost 15:05:  [orderdb02]> select order_sn,customer_id,order_id,mod(customer_id,4) from order_master;
+----------+-------------+----------+
| order_sn | customer_id | order_id |
+----------+-------------+----------+
|    70005 |       90005 |        5 |
|    70001 |       90001 |        6 |
|    70005 |       90005 |       10 |
+----------+-------------+----------+
3 rows in set (0.00 sec)

root@localhost 15:06:  [orderdb02]> select order_detail_id,product_id,order_id from order_detail;
+-----------------+------------+----------+
| order_detail_id | product_id | order_id |
+-----------------+------------+----------+
|               6 |         15 |        5 |
|               7 |         16 |        6 |
|              11 |         20 |       10 |
|              12 |         21 |        5 |
|              13 |         12 |        6 |
+-----------------+------------+----------+
5 rows in set (0.00 sec)

原文：https://www.cnblogs.com/jenvid/p/10180461.html

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