MySQL組複製的幾個常見問題以及解決辦法

MySQL組複製提供的功能很強大，但是有時會出現一些問題，或者使用上存在一些限制主要包括：

一.組複製的限制:

(a)儲存引擎只能是InnoDB。

(b)二進位制日誌格式只支援ROW格式。

(c)只支援使用GTID模式。

(d)每個分組最多隻支援9個成員節點。

 

二.資料表必須有主鍵。

mysql> create table test (name varchar(100));

Query OK, 0 rows affected (0.05 sec)

 

mysql> insert into test values( now()),(now());

ERROR 3098 (HY000): The table does not comply with the requirements by an external plugin.

 

檢視日誌：

2017-08-19T06:23:22.253181Z 13 [ERROR] Plugin group_replication reported: 'Table test does not have any PRIMARY KEY. This is not compatible with Group Replication'

2017-08-19T06:24:18.493848Z 13 [ERROR] Plugin group_replication reported: 'Table test does not have any PRIMARY KEY. This is not compatible with Group Replication'

 

解決辦法：

建立有主鍵的資料表。

mysql> create table test ( name varchar(100) primary key);

Query OK, 0 rows affected (0.02 sec)

 

mysql> insert into test (name) values ('001');

Query OK, 1 row affected (0.02 sec)

 

mysql> insert into test (name) values ('002');

Query OK, 1 row affected (0.01 sec)

 

mysql> insert into test (name) values ('003');

Query OK, 1 row affected (0.00 sec)

 

mysql> insert into test (name) values (now());

Query OK, 1 row affected (0.01 sec)

三.資料庫已經存在:

日誌中出現了資料庫已經存在而無法建立資料庫的錯誤。

2017-08-19T06:51:50.784471Z 28 [ERROR] Slave SQL for channel 'group_replication_recovery': Error 'Can't create database 'test'; database exists' on query. Default database: 'test'. Query: 'create database test', Error_code: 1007

2017-08-19T06:51:50.784523Z 28 [Warning] Slave: Can't create database 'test'; database exists Error_code: 1007

2017-08-19T06:51:50.784530Z 28 [ERROR] Error running query, slave SQL thread aborted. Fix the problem, and restart the slave SQL thread with "SLAVE START". We stopped at log 'binlog.000001' position 1082

解決辦法：

mysql> stop group_replication;

Query OK, 0 rows affected (9.43 sec)

mysql> drop database test;

ERROR 1290 (HY000): The MySQL server is running with the --super-read-only option so it cannot execute this statement

mysql> set global super_read_only=0;

Query OK, 0 rows affected (0.00 sec)

mysql> drop database test;

Query OK, 0 rows affected (0.00 sec)

mysql> set global super_read_only=1;

Query OK, 0 rows affected (0.00 sec)

mysql> set global group_replication_allow_local_disjoint_gtids_join=ON;

Query OK, 0 rows affected (0.00 sec)

mysql> start group_replication;

Query OK, 0 rows affected (3.19 sec)

為了防止在MySQL的節點在啟動時出現此問題，可將下面的配置加入MySQL配置檔案。

loose-group_replication_allow_local_disjoint_gtids_join=on