详解MySQL 5.7 MGR单主确定主节点方法

我们行MGR年底要上线了，每天都要看官方文档学习，做测试，坚持每天写一个小知识点，有想一起学习的么~

MySQL 5.7 MGR单主确定主节点是哪个，我们可以通过成员ID来判断，然后结合read_only参数来确认。

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[root@localhost ~]# mysql -uroot -p -P 3306 -h 127.0.0.1 mysql: [Warning] Using a password on the command line interface can be insecure. Welcome to the MySQL monitor. Commands end with ; or \g. Your MySQL connection id is 857246 Server version: 5.7.26-29-log Percona Server (GPL)   Copyright (c) 2009-2019 Percona LLC and / or its affiliates Copyright (c) 2000, 2019, Oracle and / or its affiliates. All rights reserved.   Oracle is a registered trademark of Oracle Corporation and / or its affiliates. Other names may be trademarks of their respective owners.   Type 'help;' or '\h' for help. Type '\c' to clear the current input statement.   mysql> status -------------- mysql Ver 14.14 Distrib 5.7.26-29, for Linux (x86_64) using EditLine wrapper   Connection id:   857246 Current database :  Current user :    root@127.0.0.1 SSL:      Not in use Current pager:   stdout Using outfile:   '' Using delimiter:  ; Server version:   5.7.26-29-log Percona Server (GPL) Protocol version:  10 Connection :   127.0.0.1 via TCP/IP Server characterset:  utf8mb4 Db   characterset:  utf8mb4 Client characterset:  utf8 Conn. characterset:  utf8 TCP port:    3306 Uptime:     39 days 8 hours 53 min 39 sec   Threads: 4 Questions: 4989552 Slow queries: 731837 Opens: 930 Flush tables: 1 Open tables: 924 Queries per second avg : 1.466 --------------   mysql> SHOW STATUS LIKE 'group_replication_primary_member' ; + ----------------------------------+--------------------------------------+ | Variable_name          | Value                | + ----------------------------------+--------------------------------------+ | group_replication_primary_member | 59d7f183-b8f6-11e9-863b-005056875165 | + ----------------------------------+--------------------------------------+ 1 row in set (0.00 sec)   mysql> select * from performance_schema.replication_group_members; + ---------------------------+--------------------------------------+-------------+-------------+--------------+ | CHANNEL_NAME       | MEMBER_ID              | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | + ---------------------------+--------------------------------------+-------------+-------------+--------------+ | group_replication_applier | 500dd0aa-b8f6-11e9-85ba-005056875a61 | 196.55.7.37 |    3306 | ONLINE    | | group_replication_applier | 59d7f183-b8f6-11e9-863b-005056875165 | 196.55.7.36 |    3306 | ONLINE    | | group_replication_applier | 69e1c26d-b8f6-11e9-91c1-00505687032a | 196.55.7.38 |    3306 | ONLINE    | + ---------------------------+--------------------------------------+-------------+-------------+--------------+ 3 rows in set (0.00 sec)   mysql> show variables like '%read_only' ; + -----------------------+-------+ | Variable_name     | Value | + -----------------------+-------+ | innodb_read_only   | OFF  | | read_only       | OFF  | | super_read_only    | OFF  | | transaction_read_only | OFF  | | tx_read_only     | OFF  | + -----------------------+-------+ 5 rows in set (0.01 sec)   mysql>

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持服务器之家。

原文链接：https://blog.51cto.com/roidba/2438715