Mycat中如何配置schmea.xml

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1.基本环境

2.schemal配置

1. 
   

2. 
   

3. 
   

4. 
   

5. dataNode="dn1"> ---默认数据节点，若新建一张表company2未在配置文件中配置，则默认建立在dn1数据节点上（私有表）
   

6. 
   

7. ---分片表，根据对应的分片规则 分片到各个物理节点上
   

   
   

   
   

   
   

   ---全局表,每个节点上都有的表
   

   ---等同于company

   ----等同于company2

8. 
   

   
   

   rule="mod-long" />
   

   
   

   rule="sharding-by-intfile" />
   

   rule="sharding-by-intfile">
   

   parentKey="id">
   

   parentKey="id" />
   

   
   

   parentKey="id" />
   

   
   

9. 
   

10. 
    

11. 
    




1. ----数据节点对应的localhost以及真实的数据库
   

2. 
   

3. 
   

4. 
   

5. 
   

6. 
   

7. balance="2" ------localhosts对应的连接配置信息
   

8. writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100">
   

9. select user()
   

10. 
    

12. password="ESBecs00">
    

13. 
    

14. 
    

15. 
    

16. 
    

17. 
    

18. 
    

20. writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100">
    

21. select user()
    

22. 
    

24. password="ESBecs00">
    

25. 
    

26. 
    

27. 
    

28. 
    

29. 
    

31. writeType="0" dbType="mysql" dbDriver="native" switchType="1" slaveThreshold="100">
    

32. select user()
    

33. 
    

35. password="ESBecs00">
    

36. 
    

37. 
    

38. 
    

39. 
    

41. ......未完待续


全局表的查询有负载均衡的作用


1. mysql> select * from company; ----本应该是相同的数据，改为不同的数据是为了展示负载均衡的效果
   

2. +----+-------------+
   

3. | id | name |
   

4. +----+-------------+
   

5. | 1 | this is 119 |
   

6. +----+-------------+
   

7. 1 row in set (0.01 sec)
   

8. 
   

9. mysql> select * from company;
   

10. +----+-------------+
    

11. | id | name |
    

12. +----+-------------+
    

13. | 1 | this is 120 |
    

14. +----+-------------+
    

15. 1 row in set (0.01 sec)
    

16. 
    

17. mysql> select * from company;
    

18. +----+-------------+
    

19. | id | name |
    

20. +----+-------------+
    

21. | 1 | this is 121 |
    

22. +----+-------------+
    

23. 1 row in set (0.00 sec)





分片表和私有表如果不在一哥节点上就联合查不到了！

uc分片表，4101在第二个节点上
act为私有表，4101在第一个节点上
select * from uc_coupon where COUPON_ID=4101 ; --单独查，是有的
select * from act_vote_info where id=4101; ---单独查，是有的
select a.*,b.* from uc_coupon a,act_vote_info b where a.COUPON_ID=b.id and b.id=4101 limit 1; --联合查，查不到了，因为跨节点了！
举例：


1. mysql> select * from order2; ---分片表
   

2. +----+----------+---------+---------------------+
   

3. | ID | PROVINCE | SN | CREATE_TIME |
   

4. +----+----------+---------+---------------------+
   

5. | 2 | shanghai | 2BJ0001 | 2017-05-09 15:01:33 | ---节点2上
   

6. | 1 | beijing | 2BJ0001 | 2017-04-23 21:48:08 | ---节点1上
   

7. | 3 | tianjin | 2BJ0001 | 2017-05-09 15:01:45 |
   

8. +----+----------+---------+---------------------+
   

9. 3 rows in set (0.00 sec)
   

10. 
    

11. mysql> select * from tt; ---私有表 节点1上
    

12. +------+------------+
    

13. | id | name |
    

14. +------+------------+
    

15. | 2 | zhangsanli |
    

16. | 1 | 12314 |
    

17. +------+------------+
    

18. 2 rows in set (0.00 sec)
    

19. 
    

20. mysql> select a.*,b.* from tt a,order2 b where a.id=b.ID and b.id=2; -----2和私有表不在一个节点上，查不出来
    

21. Empty set (0.00 sec)
    

22. 
    

23. mysql> select a.*,b.* from tt a,order2 b where a.id=b.ID and b.id=1; -----1和私有表在一个节点上，所以查的出来
    

24. +------+-------+----+----------+---------+---------------------+
    

25. | id | name | ID | PROVINCE | SN | CREATE_TIME |
    

26. +------+-------+----+----------+---------+---------------------+
    

27. | 1 | 12314 | 1 | beijing | 2BJ0001 | 2017-04-23 21:48:08 |
    

28. +------+-------+----+----------+---------+---------------------+
    

29. 1 row in set (0.00 sec)


同理：

分片表和分片表条件数据如果不在一个节点上就联合查不到了！


1. mysql> select a.* ,b.* from order2 a,order3 b where a.id=b.id and a.id=2; --单独都是有数据的，但是id相等的分在不同的节点上，还是不能跨节点
   

2. Empty set (0.00 sec)

mysql> select * from order2;
+----+----------+---------+---------------------+
| ID | PROVINCE | SN | CREATE_TIME |
+----+----------+---------+---------------------+
| 2 | shanghai | 2BJ0001 | 2017-05-09 15:01:33 |
| 1 | beijing | 2BJ0001 | 2017-04-23 21:48:08 |
| 3 | tianjing | 2BJ0001 | 2017-05-15 14:52:17 |
+----+----------+---------+---------------------+
3 rows in set (0.00 sec)


mysql> select * from order3;
+----+----------+---------+---------------------+
| ID | PROVINCE | SN | CREATE_TIME |
+----+----------+---------+---------------------+
| 2 | beijing | 2BJ0001 | 2017-05-15 14:56:27 |
| 1 | tianjing | 2BJ0001 | 2017-05-15 14:56:35 |
| 3 | shanghai | 2BJ0001 | 2017-05-15 14:56:17 |
+----+----------+---------+---------------------+
3 rows in set (0.00 sec)






解决办法：注解，详细用法见文档

1. mysql> /*!mycat:catlet=demo.catlets.ShareJoin */ select b.sn,b.CREATE_TIME,a.CREATE_TIME from order2 a,order3 b where a.id=b.id;
   

2. +---------------------+----+---------+---------------------+
   

3. | CREATE_TIME | id | sn | CREATE_TIME |
   

4. +---------------------+----+---------+---------------------+
   

5. | 2017-04-23 21:48:08 | 1 | 2BJ0001 | 2017-05-15 14:56:35 |
   

6. | 2017-05-09 15:01:33 | 2 | 2BJ0001 | 2017-05-15 14:56:27 |
   

7. | 2017-05-15 14:52:17 | 3 | 2BJ0001 | 2017-05-15 14:56:17 |
   

8. +---------------------+----+---------+---------------------+

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