要对组复制群组执行离线升级，需要将每个成员从群组中移除，升级该成员，然后像平常一样重新启动群组。在多主群组中，可以按任意顺序关闭成员。在单主群组中，应先关闭每个从属节点，最后关闭主节点。有关如何从群组中移除成员并关闭 MySQL，请参见 第 20.8.3.2 节，“升级组复制成员”。To perform an offline upgrade of a Group Replication group, you remove each member from the group, perform an upgrade of the member and then restart the group as usual. In a multi-primary group you can shutdown the members in any order. In a single-primary group, shutdown each secondary first and then finally the primary. See Section 20.8.3.2, “Upgrading a Group Replication Member” for how to remove members from a group and shutdown MySQL.

群组离线后，升级所有成员。有关如何执行升级，请参见 第 3 章，升级 MySQL。所有成员升级完成后，重新启动这些成员。Once the group is offline, upgrade all of the members. See Chapter 3, Upgrading MySQL for how to perform an upgrade. When all members have been upgraded, restart the members.

如果在复制组的所有成员处于离线状态时升级它们，然后重新启动该组，成员将使用新版本的组复制通信协议版本加入，从而该版本成为组的通信协议版本。如果您需要允许使用较早版本的成员加入，可以使用group_replication_set_communication_protocol()函数来降级通信协议版本，指定即将加入组的成员中安装版本最早的 MySQL 服务器版本。If you upgrade all the members of a replication group when they are offline and then restart the group, the members join using the new release's Group Replication communication protocol version, so that becomes the group's communication protocol version. If you have a requirement to allow members at earlier releases to join, you can use the group_replication_set_communication_protocol() function to downgrade the communication protocol version, specifying the MySQL Server version of the prospective group member that has the oldest installed server version.