Movatterモバイル変換

Use thegroup_replication_switch_to_single_primary_mode() function to change a group running in multi-primary mode to single-primary mode by issuing:

SELECT group_replication_switch_to_single_primary_mode()

When you change to single-primary mode, strict consistency checks are also disabled on all group members, as required in single-primary mode (group_replication_enforce_update_everywhere_checks=OFF).

If no string is passed in, the election of the new primary in the resulting single-primary group follows the election policies described inSection 20.1.3.1, “Single-Primary Mode”. To override the election process and configure a specific member of the multi-primary group as the new primary in the process, get theserver_uuid of the member and pass it to group_replication_switch_to_single_primary_mode(). For example, issue:

SELECT group_replication_switch_to_single_primary_mode(member_uuid);

Use thegroup_replication_switch_to_multi_primary_mode() function to change a group running in single-primary mode to multi-primary mode by issuing:

SELECT group_replication_switch_to_multi_primary_mode()

After some coordinated group operations to ensure the safety and consistency of your data, all members which belong to the group become primaries.

When you change a group from single-primary mode to multi-primary mode, members are automatically placed in read-only mode if they are running a later MySQL server version than the lowest version present in the group.

While the action runs, you can check its progress by issuing the followingSELECT statement:

SELECT event_name, work_completed, work_estimated FROM performance_schema.events_stages_current WHERE event_name LIKE "%stage/group_rpl%";+----------------------------------------------------------------------+----------------+----------------+| event_name                                                           | work_completed | work_estimated |+----------------------------------------------------------------------+----------------+----------------+| stage/group_rpl/Multi-primary Switch: applying buffered transactions |              0 |              1 |+----------------------------------------------------------------------+----------------+----------------+