Mycat中如何配置schmea.xml

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1.基本环境

2.schemal配置

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.         

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.                 

11.                 

12.                                    password="ESBecs00">

13.                         

14.                 

16.         

17.         

19.         

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

21.                 select user()

22.                 

23.                 

24.                                    password="ESBecs00">

25.                         

26.                 

28.         

30.         

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

32.                 select user()

33.                 

34.                 

35.                                    password="ESBecs00">

36.                         

37.                 

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)

9. mysql> select * from company;

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

11. | id | name |

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

13. | 1 | this is 120 |

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

15. 1 row in set (0.01 sec)

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)

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)

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)

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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