时间：2020-10-07 14:26:03 | 栏目：Mysql | 点击：次
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。
[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>