How to determine the MGR master node in Single-Primary mode (document ID 2214438.1)

MySQL 5.7

This can be determined by global status group_replication_primary_member

root@db20:59: [mgr]> SELECT VARIABLE_VALUE -> FROM performance_schema.global_status -> WHERE VARIABLE_NAME = 'group_replication_primary_member';+--------------------------------------+| VARIABLE_VALUE |+--------------------------------------+| f8da6826-328a-11e9-8e54-000c29d7ca48 |+--------------------------------------+1 row in set (0.00 sec)

The hostname and port information can be obtained in conjunction with the performance_schema.replication_group_members table:

root@db21:05: [mgr]> SELECT -> MEMBER_HOST, MEMBER_PORT -> FROM -> performance_schema.replication_group_members -> WHERE -> MEMBER_ID = (SELECT -> VARIABLE_VALUE -> FROM -> performance_schema.global_status -> WHERE -> VARIABLE_NAME = 'group_replication_primary_member');+-------------+-------------+| MEMBER_HOST | MEMBER_PORT |+-------------+-------------+| mgr1 | 3306 |+-------------+-------------+1 row in set (0.00 sec)

Or get all member information:

root@db21:05: [mgr]> SELECT -> MEMBER_ID, -> MEMBER_HOST, -> MEMBER_PORT, -> MEMBER_STATE, -> IF(global_status.VARIABLE_NAME IS NOT NULL, -> 'PRIMARY', -> 'SECONDARY') AS MEMBER_ROLE -> FROM -> performance_schema.replication_group_members -> LEFT JOIN -> performance_schema.global_status ON global_status.VARIABLE_NAME = 'group_replication_primary_member' -> AND global_status.VARIABLE_VALUE = replication_group_members.MEMBER_ID;+--------------------------------------+-------------+-------------+--------------+-------------+| MEMBER_ID | MEMBER_HOST | MEMBER_PORT | MEMBER_STATE | MEMBER_ROLE |+--------------------------------------+-------------+-------------+--------------+-------------+| f8da6826-328a-11e9-8e54-000c29d7ca48 | mgr1 | 3306 | ONLINE | PRIMARY || 030930d7-32b2-11e9-8298-000c292aafc5 | mgr2 | 3306 | ONLINE | SECONDARY || 202bdcd5-32b3-11e9-9f4f-000c29322d33 | mgr3 | 3306 | ONLINE | SECONDARY |+--------------------------------------+-------------+-------------+--------------+-------------+3 rows in set (0.01 sec)MySQL 8.0.2 and Later

MySQL 8.0.2 started, Performance Schema extended

SELECT MEMBER_HOST, MEMBER_PORT FROM performance_schema.replication_group_members WHERE MEMBER_ROLE = 'PRIMARY';

Or get all member information:

mysql> SELECT MEMBER_ID, MEMBER_HOST, MEMBER_PORT, MEMBER_STATE, MEMBER_ROLE, MEMBER_VERSION FROM performance_schema.replication_group_members;