MySQL學習筆記16分組復制的幾個常見問題以及解決辦法
MySQL分組復制提供的功能很強大，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：
(1)分組復制的限制。
(a)存儲引擎只能是InnoDB。
(b)二進制日誌格式只支持ROW格式。
(c)只支持使用GTID模式。
(d)每個分組最多只支持9個成員節點。
(2)數據表必須有主鍵。
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.
查看日誌：
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：
創建有主鍵的數據表。
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)
(3)數據庫已經存在。
日誌中出現了數據庫已經存在而無法創建數據庫的錯誤。
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配置文件。
loose-group_replication_allow_local_disjoint_gtids_join=on
MySQL學習筆記16分組復制的幾個常見問題以及解決辦法