group_replication_single_primary_mode

group_replication_enforce_update_everywhere_checks

group_replication_gtid_assignment_block_size

group_replication_view_change_uuid（已弃用）group_replication_view_change_uuid (deprecated)

group_replication_paxos_single_leader

group_replication_communication_stack（一种特殊情况，不受 Group Replication 自身检查的限制；详情请参见系统变量描述）group_replication_communication_stack (a special case not policed by Group Replication's own checks; see the system variable description for details)

default_table_encryptiondefault_table_encryption

lower_case_table_nameslower_case_table_names

group_replication_auto_increment_increment

group_replication_communication_max_message_size

group_replication_compression_threshold

group_replication_message_cache_size

group_replication_transaction_size_limit

group_replication_advertise_recovery_endpoints

group_replication_autorejoin_tries

group_replication_consistency

group_replication_exit_state_action

group_replication_flow_control_applier_threshold

group_replication_flow_control_certifier_threshold

group_replication_flow_control_hold_percent

group_replication_flow_control_max_quota

group_replication_flow_control_member_quota_percent

group_replication_flow_control_min_quota

group_replication_flow_control_min_recovery_quota

group_replication_flow_control_mode

group_replication_flow_control_period

group_replication_flow_control_release_percent

group_replication_force_members

group_replication_ip_allowlist

group_replication_member_expel_timeout

group_replication_member_weight

group_replication_transaction_size_limit

group_replication_unreachable_majority_timeout

group_replication_advertise_recovery_endpoints

在组复制运行期间，可以更改此系统变量的值。更改会立即在当前成员上生效。然而，已经收到系统变量先前值的加入成员将继续使用该值。只有在值更改后加入的成员才会接收新值。The value of this system variable can be changed while Group Replication is running. The change takes effect immediately on the member. However, a joining member that already received the previous value of the system variable continues to use that value. Only members that join after the value change receive the new value.

group_replication_advertise_recovery_endpoints 指定了加入成员如何建立与现有成员的连接，以进行分布式恢复的状态传输。该连接用于远程克隆操作以及从捐献者的二进制日志进行的状态传输。group_replication_advertise_recovery_endpoints specifies how a joining member can establish a connection to an existing member for state transfer for distributed recovery. The connection is used for both remote cloning operations and state transfer from the donor's binary log.

值为 DEFAULT，即默认设置，表示加入的成员使用现有成员的标准 SQL 客户端连接，如 MySQL 服务器的 hostname 和 port 系统变量所指定。如果通过 report_port 系统变量指定了替代的端口号，则使用该端口号。Performance Schema 表 replication_group_members 在 MEMBER_HOST 和 MEMBER_PORT 列中显示此连接的地址和端口号。A value of DEFAULT, which is the default setting, means joining members use the existing member's standard SQL client connection, as specified by MySQL Server's hostname and port system variables. If an alternative port number is specified by the report_port system variable, that one is used instead. The Performance Schema table replication_group_members shows this connection's address and port number in the MEMBER_HOST and MEMBER_PORT columns.

你可以指定一个或多个分布式恢复端点，而不是使用 DEFAULT，现有成员会向加入的成员宣传这些端点以供使用。提供分布式恢复端点可以让管理员将分布式恢复流量与普通 MySQL 客户端连接到组成员的流量分别控制。加入的成员会按列表中指定的顺序依次尝试每一个端点。Instead of DEFAULT, you can specify one or more distributed recovery endpoints, which the existing member advertises to joining members for them to use. Offering distributed recovery endpoints lets administrators control distributed recovery traffic separately from regular MySQL client connections to the group members. Joining members try each of the endpoints in turn in the order they are specified on the list.

将分布式恢复端点指定为逗号分隔的 IP 地址和端口号列表，例如：Specify the distributed recovery endpoints as a comma-separated list of IP addresses and port numbers, for example:

group_replication_advertise_recovery_endpoints= "127.0.0.1:3306,127.0.0.1:4567,[::1]:3306,localhost:3306"

IPv4 和 IPv6 地址以及主机名可以任意组合使用。IPv6 地址必须用方括号括起来。主机名必须解析为本地 IP 地址。不能使用通配符地址格式，也不能指定空列表。请注意，标准 SQL 客户端连接不会自动包含在分布式恢复端点列表中。如果您想将其用作端点，必须在列表中明确包含它。IPv4 and IPv6 addresses and host names can be used in any combination. IPv6 addresses must be specified in square brackets. Host names must resolve to a local IP address. Wildcard address formats cannot be used, and you cannot specify an empty list. Note that the standard SQL client connection is not automatically included on a list of distributed recovery endpoints. If you want to use it as an endpoint, you must include it explicitly on the list.

有关如何选择 IP 地址和端口作为分布式恢复端点，以及加入成员如何使用它们的详细信息，请参见 第 20.5.4.1.1 节，“选择分布式恢复端点的地址”。要求总结如下：For details of how to select IP addresses and ports as distributed recovery endpoints, and how joining members use them, see Section 20.5.4.1.1, “Selecting addresses for distributed recovery endpoints”. A summary of the requirements is as follows:

group_replication_allow_local_lower_version_join

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_allow_local_lower_version_join 允许当前服务器加入组，即使它运行的 MySQL 服务器版本低于组中的其他成员。默认设置为 OFF 时，如果服务器运行的版本低于现有组成员，则不允许其加入复制组。这一标准策略确保组内的所有成员能够交换消息和应用事务。group_replication_allow_local_lower_version_join allows the current server to join the group even if it is running a lower MySQL Server version than the group. With the default setting OFF, servers are not permitted to join a replication group if they are running a lower version than the existing group members. This standard policy ensures that all members of a group are able to exchange messages and apply transactions.

仅在以下情况下将 group_replication_allow_local_lower_version_join 设置为 ON：Set group_replication_allow_local_lower_version_join to ON only in the following scenarios:

group_replication_auto_increment_increment

此系统变量在所有组成员上应具有相同的值。在组复制运行时，您无法更改此系统变量的值。您必须停止组复制，更改系统变量的值，然后在每个组成员上重新启动组复制。在此过程中，系统变量的值允许在组成员之间有所不同，但组成员上的某些事务可能会被回滚。This system variable should have the same value on all group members. You cannot change the value of this system variable while Group Replication is running. You must stop Group Replication, change the value of the system variable, then restart Group Replication, on each of the group members. During this process, the value of the system variable is permitted to differ between group members, but some transactions on group members might be rolled back.

group_replication_auto_increment_increment 决定在此服务器实例上执行的事务的自增列连续值之间的间隔。增加间隔可以避免在组成员上写入时选择重复的自增值，从而导致事务回滚。默认值 7 代表可用值的数量与允许的复制组最大规模（9 个成员）之间的平衡。如果您的组成员数量更多或更少，可以在启动组复制之前将此系统变量设置为匹配预期的组成员数量。group_replication_auto_increment_increment determines the interval between successive values for auto-incremented columns for transactions that execute on this server instance. Adding an interval avoids the selection of duplicate auto-increment values for writes on group members, which causes rollback of transactions. The default value of 7 represents a balance between the number of usable values and the permitted maximum size of a replication group (9 members). If your group has more or fewer members, you can set this system variable to match the expected number of group members before Group Replication is started.

当在服务器实例上启动群组复制（Group Replication）时，服务器系统变量 auto_increment_increment 的值会被更改为此值，服务器系统变量 auto_increment_offset 的值会被更改为服务器 ID。当群组复制停止时，这些更改会恢复。只有在 auto_increment_increment 和 auto_increment_offset 的值都为默认值 1 时，这些更改才会被执行和恢复。如果它们的值已经被修改过，群组复制不会更改它们。当群组复制处于单主模式（single-primary mode），即只有一台服务器写入时，这些系统变量也不会被修改。When Group Replication is started on a server instance, the value of the server system variable auto_increment_increment is changed to this value, and the value of the server system variable auto_increment_offset is changed to the server ID. The changes are reverted when Group Replication is stopped. These changes are only made and reverted if auto_increment_increment and auto_increment_offset each have their default value of 1. If their values have already been modified from the default, Group Replication does not alter them. The system variables are also not modified when Group Replication is in single-primary mode, where only one server writes.

group_replication_autorejoin_tries

在组复制运行期间，可以更改此系统变量的值，并且更改会立即生效。当发生需要该行为的问题时，会读取该系统变量的当前值。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately. The system variable's current value is read when an issue occurs that means the behavior is needed.

group_replication_autorejoin_tries 指定了当成员被开除，或者在达到 group_replication_unreachable_majority_timeout 设置值之前无法联系到群体大多数成员时，成员尝试自动重新加入群体的次数。当成员被开除或不可达多数超时达到时，它会尝试重新加入（使用当前插件选项值），然后继续进行进一步的自动重新加入尝试，直到达到指定的尝试次数。在自动重新加入尝试失败后，成员会在下一次尝试前等待 5 分钟。如果在耗尽指定尝试次数后成员仍未重新加入或被停止，成员将执行由 group_replication_exit_state_action 系统变量指定的操作。group_replication_autorejoin_tries specifies the number of tries that a member makes to automatically rejoin the group if it is expelled, or if it is unable to contact a majority of the group before the group_replication_unreachable_majority_timeout setting is reached. When the member's expulsion or unreachable majority timeout is reached, it makes an attempt to rejoin (using the current plugin option values), then continues to make further auto-rejoin attempts up to the specified number of tries. After an unsuccessful auto-rejoin attempt, the member waits 5 minutes before the next try. If the specified number of tries is exhausted without the member rejoining or being stopped, the member proceeds to the action specified by the group_replication_exit_state_action system variable.

在自动重新加入尝试期间和尝试之间，成员保持超级只读模式，不接受写入，但仍可以在该成员上进行读取，随着时间推移，陈旧读取的可能性会增加。如果您无法容忍任何时间段内可能出现的陈旧读取，请将 group_replication_autorejoin_tries 设置为 0。有关自动重新加入功能的更多信息，以及选择此选项值时的注意事项，请参见 第 20.7.7.3 节，“自动重新加入”。During and between auto-rejoin attempts, a member remains in super read only mode and does not accept writes, but reads can still be made on the member, with an increasing likelihood of stale reads over time. If you cannot tolerate the possibility of stale reads for any period of time, set group_replication_autorejoin_tries to 0. For more information on the auto-rejoin feature, and considerations when choosing a value for this option, see Section 20.7.7.3, “Auto-Rejoin”.

group_replication_bootstrap_group

group_replication_bootstrap_group 配置此服务器以引导该组。此系统变量必须仅在一台服务器上设置，并且仅在首次启动组或重新启动整个组时设置。组引导完成后，将此选项设置为OFF。它应该在动态设置和配置文件中都设置为OFF。在组运行期间，如果启动两台服务器或重启一台服务器，并且设置了此选项，可能导致人为的脑裂情况，即两个独立的具有相同名称的组被引导。group_replication_bootstrap_group configures this server to bootstrap the group. This system variable must only be set on one server, and only when starting the group for the first time or restarting the entire group. After the group has been bootstrapped, set this option to OFF. It should be set to OFF both dynamically and in the configuration files. Starting two servers or restarting one server with this option set while the group is running may lead to an artificial split brain situation, where two independent groups with the same name are bootstrapped.

有关首次引导群组的说明，请参见 第 20.2.1.5 节，“引导群组”。有关在已经执行并认证事务的情况下安全引导群组的说明，请参见 第 20.5.2 节，“重新启动群组”。For instructions to bootstrap a group for the first time, see Section 20.2.1.5, “Bootstrapping the Group”. For instructions to safely bootstrap a group where transactions have been executed and certified, see Section 20.5.2, “Restarting a Group”.

group_replication_clone_threshold

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_clone_threshold 指定在分布式恢复过程中，用于触发向加入成员传输状态的远程克隆操作时，现有成员（提供者）与加入成员（接收者）之间的事务差距（以事务数量计）。如果加入成员与合适的提供者之间的事务差距超过阈值，组复制将开始使用远程克隆操作进行分布式恢复。如果事务差距低于阈值，或者远程克隆操作在技术上不可行，组复制将直接从提供者的二进制日志进行状态传输。group_replication_clone_threshold specifies the transaction gap, as a number of transactions, between the existing member (donor) and the joining member (recipient) that triggers the use of a remote cloning operation for state transfer to the joining member during the distributed recovery process. If the transaction gap between the joining member and a suitable donor exceeds the threshold, Group Replication begins distributed recovery with a remote cloning operation. If the transaction gap is below the threshold, or if the remote cloning operation is not technically possible, Group Replication proceeds directly to state transfer from a donor's binary log.

要使用此功能，必须事先设置捐赠者和加入的成员以支持克隆。有关说明，请参见 第 20.5.4.2 节，“分布式恢复的克隆”。当执行远程克隆操作时，如果设置了 group_replication_start_on_boot=ON，Group Replication 会为您管理此操作，包括所需的服务器重启。如果未设置，您必须手动重启服务器。远程克隆操作会替换加入成员上现有的数据字典，但如果加入成员具有其他组成员中不存在的额外事务，Group Replication 会进行检查并且不会继续操作，因为这些事务将在克隆操作中被删除。To use this function, both the donor and the joining member must be set up beforehand to support cloning. For instructions, see Section 20.5.4.2, “Cloning for Distributed Recovery”. When a remote cloning operation is carried out, Group Replication manages it for you, including the required server restart, provided that group_replication_start_on_boot=ON is set. If not, you must restart the server manually. The remote cloning operation replaces the existing data dictionary on the joining member, but Group Replication checks and does not proceed if the joining member has additional transactions that are not present on the other group members, because these transactions would be erased by the cloning operation.

默认设置（即 GTID 中事务允许的最大序列号）意味着几乎总是尝试从捐赠者的二进制日志进行状态传输，而不是克隆。然而，请注意，如果无法从捐赠者的二进制日志进行状态传输，例如因为加入成员所需的事务在任何现有组成员的二进制日志中都不可用，Group Replication 总是会尝试执行克隆操作，而不考虑您的阈值。如果您完全不想在复制组中使用克隆，请不要在成员上安装克隆插件。The default setting (which is the maximum permitted sequence number for a transaction in a GTID) means that state transfer from a donor's binary log is virtually always attempted rather than cloning. However, note that Group Replication always attempts to execute a cloning operation, regardless of your threshold, if state transfer from a donor's binary log is impossible, for example because the transactions needed by the joining member are not available in the binary logs on any existing group member. If you do not want to use cloning at all in your replication group, do not install the clone plugin on the members.

group_replication_communication_debug_options

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_communication_debug_options 配置为不同的组复制组件（如组通信系统（GCS）和组通信引擎（XCom，一种 Paxos 变体））提供调试消息的级别。调试信息存储在数据目录中的 GCS_DEBUG_TRACE 文件中。group_replication_communication_debug_options configures the level of debugging messages to provide for the different Group Replication components, such as the Group Communication System (GCS) and the group communication engine (XCom, a Paxos variant). The debug information is stored in the GCS_DEBUG_TRACE file in the data directory.

可用选项集以字符串形式指定，可以组合使用。可用的选项如下：The set of available options, specified as strings, can be combined. The following options are available:

将调试级别设置为 GCS_DEBUG_NONE 仅在没有提供其他选项时才有效。将调试级别设置为 GCS_DEBUG_ALL 会覆盖所有其他选项。Setting the debug level to GCS_DEBUG_NONE only has an effect when provided without any other option. Setting the debug level to GCS_DEBUG_ALL overrides all other options.

group_replication_communication_max_message_size

此系统变量在所有组成员上应具有相同的值。在组复制运行时，您无法更改此系统变量的值。您必须停止组复制，更改系统变量的值，然后在每个组成员上重新启动组复制。在此过程中，系统变量的值允许在组成员之间有所不同，但组成员上的某些事务可能会被回滚。This system variable should have the same value on all group members. You cannot change the value of this system variable while Group Replication is running. You must stop Group Replication, change the value of the system variable, then restart Group Replication, on each of the group members. During this process, the value of the system variable is permitted to differ between group members, but some transactions on group members might be rolled back.

group_replication_communication_max_message_size 指定了组复制通信的最大消息大小。大于此大小的消息将自动拆分为单独发送的片段，并由接收方重新组装。欲了解更多信息，请参见 第 20.7.5 节，“消息分片”。group_replication_communication_max_message_size specifies a maximum message size for Group Replication communications. Messages greater than this size are automatically split into fragments that are sent separately and reassembled by the recipients. For more information, see Section 20.7.5, “Message Fragmentation”.

默认设置的最大消息大小为 10485760 字节（10 MiB），这意味着默认情况下使用分片。允许的最大值与系统变量replica_max_allowed_packet的最大值相同，为 1073741824 字节（1 GB）。group_replication_communication_max_message_size必须小于replica_max_allowed_packet，因为应用线程无法处理大于允许的最大数据包大小的消息分片。要关闭分片，请将group_replication_communication_max_message_size设置为0。A maximum message size of 10485760 bytes (10 MiB) is set by default, which means that fragmentation is used by default. The greatest permitted value is the same as the maximum value of the replica_max_allowed_packet system variable, which is 1073741824 bytes (1 GB). group_replication_communication_max_message_size must be less than replica_max_allowed_packet, because the applier thread cannot handle message fragments larger than the maximum permitted packet size. To switch off fragmentation, set group_replication_communication_max_message_size to 0.

为了让复制组的成员使用分片，该组的通信协议版本必须是 8.0.16 或更高版本。使用 group_replication_get_communication_protocol() 函数查看组的通信协议版本。如果使用的是较低版本，组成员将不会对消息进行分片。如果所有组成员都支持更高版本，可以使用 group_replication_set_communication_protocol() 函数将组的通信协议设置为更高版本。更多信息，请参见 第 20.5.1.4 节，“设置组的通信协议版本”。In order for members of a replication group to use fragmentation, the group's communication protocol version must be 8.0.16 or later. Use the group_replication_get_communication_protocol() function to view the group's communication protocol version. If a lower version is in use, group members do not fragment messages. You can use the group_replication_set_communication_protocol() function to set the group's communication protocol to a higher version if all group members support it. For more information, see Section 20.5.1.4, “Setting a Group's Communication Protocol Version”.

group_replication_communication_stack

group_replication_communication_stack 指定用于在成员之间建立组通信连接的是 XCom 通信栈还是 MySQL 通信栈。XCom 通信栈是 Group Replication 自己的实现，不支持身份验证或网络命名空间。MySQL 通信栈是 MySQL 服务器的原生实现，支持身份验证和网络命名空间，并且新安全功能在发布时即可使用。组内所有成员必须使用相同的通信栈。group_replication_communication_stack specifies whether the XCom communication stack or the MySQL communication stack is to be used to establish group communication connections between members. The XCom communication stack is Group Replication's own implementation, and does not support authentication or network namespaces. The MySQL communication stack is MySQL Server's native implementation, with support for authentication and network namespaces, and access to new security functions immediately on release. All members of a group must use the same communication stack.

当您使用 MySQL 通信栈代替 XCom 时，MySQL 服务器将使用其自己的身份验证和加密协议来建立组成员之间的每个连接。When you use the MySQL communication stack in place of XCom, MySQL Server establishes each connection between group members using its own authentication and encryption protocols.

当您设置一个组以使用 MySQL 的通信堆栈时，需要进行额外配置；请参见 第 20.6.1 节，“连接安全管理的通信堆栈”。Additional configuration is required when you set up a group to use MySQL’s communication stack; see Section 20.6.1, “Communication Stack for Connection Security Management”.

group_replication_communication_stack 实际上是一个全组的配置设置，并且该设置必须在所有组成员上相同。然而，这一设置并不会受到 Group Replication 对全组配置设置自身检查的限制。与组中其他成员设置不同的成员根本无法与其他成员通信，因为通信协议不兼容，因此它无法交换有关其配置设置的信息。group_replication_communication_stack is effectively a group-wide configuration setting, and the setting must be the same on all group members. However, this is not policed by Group Replication’s own checks for group-wide configuration settings. A member with a different value from the rest of the group cannot communicate with the other members at all, because the communication protocols are incompatible, so it cannot exchange information about its configuration settings.

这意味着，虽然在 Group Replication 正在运行时可以更改系统变量的值，并在您在该组成员上重新启动 Group Replication 后生效，但该成员在所有成员都更改设置之前仍然无法重新加入组。因此，您必须在所有成员上停止 Group Replication，并更改它们的系统变量值，然后才能重新启动组。由于所有成员都已停止，需要对组进行完全重启（由设置 group_replication_bootstrap_group=ON 的服务器引导）以使值更改生效。有关从一个通信堆栈迁移到另一个通信堆栈的说明，请参见 第 20.6.1 节，“连接安全管理的通信堆栈”。This means that although the value of the system variable can be changed while Group Replication is running, and takes effect after you restart Group Replication on the group member, the member still cannot rejoin the group until the setting has been changed on all the members. You must therefore stop Group Replication on all of the members and change the value of the system variable on them all before you can restart the group. Because all of the members are stopped, a full reboot of the group (a bootstrap by a server with group_replication_bootstrap_group=ON) is required in order for the value change to take effect. For instructions to migrate from one communication stack to another, see Section 20.6.1, “Communication Stack for Connection Security Management”.

group_replication_components_stop_timeout

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_components_stop_timeout 指定 Group Replication 在关闭时等待每个模块完成正在进行的进程的时间，单位为秒。组件超时在执行 STOP GROUP_REPLICATION 语句后生效，该语句会在服务器重启或自动重新加入期间自动执行。group_replication_components_stop_timeout specifies the time, in seconds, for which Group Replication waits for each of its modules to complete ongoing processes while shutting down. The component timeout applies after a STOP GROUP_REPLICATION statement is issued, which happens automatically during server restart or auto-rejoin.

超时用于解决 Group Replication 组件无法正常停止的情况，这可能发生在成员处于错误状态时被逐出群组，或者当某个进程（例如 MySQL Enterprise Backup）在成员上持有全局锁时。在这种情况下，成员无法停止应用线程或完成分布式恢复过程以重新加入。STOP GROUP_REPLICATION 命令不会完成，直到情况得到解决（例如通过释放锁），或者组件超时到期并且无论其状态如何都关闭模块。The timeout is used to resolve situations in which Group Replication components cannot be stopped normally, which might happen if a member is expelled from the group while it is in an error state, or while a process such as MySQL Enterprise Backup is holding a global lock on tables on the member. In such situations, the member cannot stop the applier thread or complete the distributed recovery process to rejoin. STOP GROUP_REPLICATION does not complete until either the situation is resolved (for example, by the lock being released), or the component timeout expires and the modules are shut down regardless of their status.

默认值为 300 秒，因此如果情况在此之前未得到解决，Group Replication 组件将在 5 分钟后停止，从而允许成员重启并重新加入。The default value is 300 seconds, so that Group Replication components are stopped after 5 minutes if the situation is not resolved before that time, allowing the member to be restarted and to rejoin.

group_replication_compression_threshold

该阈值以字节为单位，当消息在组成员之间发送时，如果消息大小超过该值，则会应用压缩。如果此系统变量设置为零，则禁用压缩。group_replication_compression_threshold 的值应在所有组成员上保持一致。The threshold value in bytes above which compression is applied to messages sent between group members. If this system variable is set to zero, compression is disabled. The value of group_replication_compression_threshold should be the same on all group members.

组复制使用 LZ4 压缩算法来压缩在组中发送的消息。请注意，LZ4 压缩算法支持的最大输入大小为 2113929216 字节。该限制低于 group_replication_compression_threshold 系统变量的最大可能值，该值与 XCom 接受的最大消息大小相匹配。使用 LZ4 压缩算法时，不要为 group_replication_compression_threshold 设置超过 2113929216 字节的值，因为当启用消息压缩时，超过此大小的事务无法提交。Group Replication uses the LZ4 compression algorithm to compress messages sent in the group. Note that the maximum supported input size for the LZ4 compression algorithm is 2113929216 bytes. This limit is lower than the maximum possible value for the group_replication_compression_threshold system variable, which is matched to the maximum message size accepted by XCom. With the LZ4 compression algorithm, do not set a value greater than 2113929216 bytes for group_replication_compression_threshold, because transactions above this size cannot be committed when message compression is enabled.

欲了解更多信息，请参见 第 20.7.4 节，“消息压缩”。For more information, see Section 20.7.4, “Message Compression”.

group_replication_consistency

group_replication_consistency 是一个服务器系统变量，而不是 Group Replication 插件特定的变量，因此无需重启 Group Replication 即可使更改生效。更改系统变量的会话值会立即生效，更改全局值会在更改后启动的新会话中生效。更改此系统变量的全局设置需要 GROUP_REPLICATION_ADMIN 权限。group_replication_consistency is a server system variable rather than a Group Replication plugin-specific variable, so a restart of Group Replication is not required for the change to take effect. Changing the session value of the system variable takes effect immediately, and changing the global value takes effect for new sessions that start after the change. The GROUP_REPLICATION_ADMIN privilege is required to change the global setting for this system variable.

group_replication_consistency 决定了一个群组提供的事务一致性保证；这可以全局设置，也可以针对每个事务设置。group_replication_consistency 还决定了单主群组中新选主节点使用的隔离机制。必须同时考虑该变量对只读事务和读/写事务的影响。以下列表显示了该变量的可能取值，按事务一致性保证递增顺序排列：group_replication_consistency determines the transaction consistency guarantee which a group provides; this can done globally, or per transaction. group_replication_consistency also determines the fencing mechanism used by newly elected primaries in single primary groups. The effect of the variable must be considered both for read-only and for read/write transactions. The following list shows the possible values of this variable, in order of increasing transaction consistency guarantee:

欲了解更多信息，请参阅 第 20.5.3 节，“事务一致性保证”。For more information, see Section 20.5.3, “Transaction Consistency Guarantees”.

group_replication_enforce_update_everywhere_checks

group_replication_enforce_update_everywhere_checks 启用或禁用针对多主“全域更新”的严格一致性检查。默认情况下，检查是禁用的。在单主模式下，此选项必须在所有组成员上禁用。在多主模式下，当启用此选项时，将按如下方式检查语句，以确保它们与多主模式兼容：group_replication_enforce_update_everywhere_checks enables or disables strict consistency checks for multi-primary update everywhere. The default is that checks are disabled. In single-primary mode, this option must be disabled on all group members. In multi-primary mode, when this option is enabled, statements are checked as follows to ensure they are compatible with multi-primary mode:

此系统变量是一个组范围的配置设置。它在所有组成员上必须具有相同的值，组复制运行时无法更改，并且需要对整个组进行完全重启（由启用了 group_replication_bootstrap_group=ON 的服务器引导）才能使值更改生效。有关如何在事务已执行并认证的情况下安全引导组的说明，请参阅 第 20.5.2 节，“重启一个组”。This system variable is a group-wide configuration setting. It must have the same value on all group members, cannot be changed while Group Replication is running, and requires a full reboot of the group (a bootstrap by a server with group_replication_bootstrap_group=ON) in order for the value change to take effect. For instructions to safely bootstrap a group where transactions have been executed and certified, see Section 20.5.2, “Restarting a Group”.

如果该组为此系统变量设置了值，而加入的成员为该系统变量设置了不同的值，则加入的成员在将值更改为匹配之前无法加入该组。如果组成员为此系统变量设置了值，而加入的成员不支持该系统变量，则它无法加入该组。If the group has a value set for this system variable, and a joining member has a different value set for the system variable, the joining member cannot join the group until the value is changed to match. If the group members have a value set for this system variable, and the joining member does not support the system variable, it cannot join the group.

使用 group_replication_switch_to_single_primary_mode() 和 group_replication_switch_to_multi_primary_mode() 函数在组仍在运行时更改此系统变量的值。有关详细信息，请参阅 第 20.5.1.2 节，“更改组模式”。Use the group_replication_switch_to_single_primary_mode() and group_replication_switch_to_multi_primary_mode() functions to change the value of this system variable while the group is still running. For more information, see Section 20.5.1.2, “Changing the Group Mode”.

group_replication_exit_state_action

在组复制运行期间，可以更改此系统变量的值，并且更改会立即生效。当发生需要该行为的问题时，会读取该系统变量的当前值。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately. The system variable's current value is read when an issue occurs that means the behavior is needed.

group_replication_exit_state_action 配置当该服务器实例意外离开组时 Group Replication 的行为，例如在遇到应用程序错误后，或者在失去多数成员的情况下，或者当组中的其他成员因为怀疑超时而将其驱逐时。成员在失去多数的情况下离开组的超时时间由 group_replication_unreachable_majority_timeout 系统变量设置，怀疑超时的时间由 group_replication_member_expel_timeout 系统变量设置。请注意，被驱逐的组成员在重新连接到组之前不会知道自己已被驱逐，因此指定的操作只有在成员成功重新连接，或者成员对自己产生怀疑并自我驱逐时才会执行。group_replication_exit_state_action configures how Group Replication behaves when this server instance leaves the group unintentionally, for example after encountering an applier error, or in the case of a loss of majority, or when another member of the group expels it due to a suspicion timing out. The timeout period for a member to leave the group in the case of a loss of majority is set by the group_replication_unreachable_majority_timeout system variable, and the timeout period for suspicions is set by the group_replication_member_expel_timeout system variable. Note that an expelled group member does not know that it was expelled until it reconnects to the group, so the specified action is only taken if the member manages to reconnect, or if the member raises a suspicion on itself and expels itself.

当由于怀疑超时或失去多数而导致某个组成员被开除时，如果该成员已将 group_replication_autorejoin_tries 系统变量设置为指定的自动重新加入尝试次数，它会首先在超级只读模式下进行指定次数的尝试，然后执行 group_replication_exit_state_action 指定的操作。出现应用器错误时不会进行自动重新加入尝试，因为这些错误是不可恢复的。When a group member is expelled due to a suspicion timing out or a loss of majority, if the member has the group_replication_autorejoin_tries system variable set to specify a number of auto-rejoin attempts, it first makes the specified number of attempts while in super read only mode, and then follows the action specified by group_replication_exit_state_action. Auto-rejoin attempts are not made in case of an applier error, because these are not recoverable.

当 group_replication_exit_state_action 设置为 READ_ONLY 时，如果成员非预期地退出组或耗尽其自动重新加入的尝试，该实例会将 MySQL 切换为超级只读模式（通过将系统变量 super_read_only 设置为 ON）。When group_replication_exit_state_action is set to READ_ONLY, if the member exits the group unintentionally or exhausts its auto-rejoin attempts, the instance switches MySQL to super read only mode (by setting the system variable super_read_only to ON).

当 group_replication_exit_state_action 设置为 OFFLINE_MODE 时，如果成员非意图地退出组或耗尽其自动重加入尝试，实例会将 MySQL 切换到离线模式（通过将系统变量 offline_mode 设置为 ON）。在此模式下，已连接的客户端用户在下一次请求时会被断开连接，并且不再接受新连接，唯一例外的是拥有 CONNECTION_ADMIN 权限（或已弃用的 SUPER 权限）的客户端用户。群复制还会将系统变量 super_read_only 设置为 ON，因此即使客户端拥有 CONNECTION_ADMIN 或 SUPER 权限，也无法进行任何更新操作。When group_replication_exit_state_action is set to OFFLINE_MODE, if the member exits the group unintentionally or exhausts its auto-rejoin attempts, the instance switches MySQL to offline mode (by setting the system variable offline_mode to ON). In this mode, connected client users are disconnected on their next request and connections are no longer accepted, with the exception of client users that have the CONNECTION_ADMIN privilege (or the deprecated SUPER privilege). Group Replication also sets the system variable super_read_only to ON, so clients cannot make any updates, even if they have connected with the CONNECTION_ADMIN or SUPER privilege.

当 group_replication_exit_state_action 设置为 ABORT_SERVER 时，如果成员非自愿退出组或用尽了自动重新加入尝试，实例将关闭 MySQL。When group_replication_exit_state_action is set to ABORT_SERVER, if the member exits the group unintentionally or exhausts its auto-rejoin attempts, the instance shuts down MySQL.

有关使用此选项的更多信息，以及执行退出操作的完整情况列表，请参阅 第 20.7.7.4 节，“退出操作”。For more information on using this option, and the full list of situations in which the exit action is taken, see Section 20.7.7.4, “Exit Action”.

group_replication_flow_control_applier_threshold

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_applier_threshold 指定应用器队列中等待的事务数量，该数量触发流量控制。group_replication_flow_control_applier_threshold specifies the number of waiting transactions in the applier queue that trigger flow control.

group_replication_flow_control_certifier_threshold

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_certifier_threshold 指定触发流控的认证队列中等待事务的数量。group_replication_flow_control_certifier_threshold specifies the number of waiting transactions in the certifier queue that trigger flow control.

group_replication_flow_control_hold_percent

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_hold_percent 定义了为了让处于流量控制下的集群赶上积压任务，组配额中未使用的百分比。值为 0 表示配额中没有部分是保留用于赶上工作积压的。group_replication_flow_control_hold_percent defines what percentage of the group quota remains unused to allow a cluster under flow control to catch up on backlog. A value of 0 implies that no part of the quota is reserved for catching up on the work backlog.

group_replication_flow_control_max_quota

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_max_quota 定义了组的最大流控配额，或者在启用流控时任何周期的最大可用配额。值为 0 表示没有设置最大配额。此系统变量的值不能小于 group_replication_flow_control_min_quota 和 group_replication_flow_control_min_recovery_quota。group_replication_flow_control_max_quota defines the maximum flow control quota of the group, or the maximum available quota for any period while flow control is enabled. A value of 0 implies that there is no maximum quota set. The value of this system variable cannot be smaller than group_replication_flow_control_min_quota and group_replication_flow_control_min_recovery_quota.

group_replication_flow_control_member_quota_percent

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_member_quota_percent 定义了成员在计算配额时应认为自己可用的配额百分比。值为 0 表示配额应在上一个周期中担任写入者的成员之间平均分配。group_replication_flow_control_member_quota_percent defines the percentage of the quota that a member should assume is available for itself when calculating the quotas. A value of 0 implies that the quota should be split equally between members that were writers in the last period.

group_replication_flow_control_min_quota

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_min_quota 控制可以分配给成员的最低流量控制配额，这与上一个周期执行的计算最小配额无关。值为 0 表示没有最低配额。该系统变量的值不能大于 group_replication_flow_control_max_quota。group_replication_flow_control_min_quota controls the lowest flow control quota that can be assigned to a member, independently of the calculated minimum quota executed in the last period. A value of 0 implies that there is no minimum quota. The value of this system variable cannot be larger than group_replication_flow_control_max_quota.

group_replication_flow_control_min_recovery_quota

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_min_recovery_quota 控制由于组中其他成员正在恢复而可以分配给某个成员的最低配额，这与上一周期执行的计算最小配额无关。值为 0 表示没有最低配额。此系统变量的值不能大于 group_replication_flow_control_max_quota。group_replication_flow_control_min_recovery_quota controls the lowest quota that can be assigned to a member because of another recovering member in the group, independently of the calculated minimum quota executed in the last period. A value of 0 implies that there is no minimum quota. The value of this system variable cannot be larger than group_replication_flow_control_max_quota.

group_replication_flow_control_mode

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_mode 指定用于流量控制的模式。group_replication_flow_control_mode specifies the mode used for flow control.

group_replication_flow_control_period

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_period 定义在流控迭代之间等待的秒数，在这些迭代中发送流控消息并运行流控管理任务。group_replication_flow_control_period defines how many seconds to wait between flow control iterations, in which flow control messages are sent and flow control management tasks are run.

group_replication_flow_control_release_percent

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately.

group_replication_flow_control_release_percent 定义了当流控制不再需要限制写入成员时，组配额应如何释放，该百分比表示每个流控制周期内的配额增加量。值为 0 表示一旦流控制阈值在限制范围内，配额将在一次流控制迭代中释放。该范围允许配额最多释放到当前配额的 10 倍，因为这可以提供更大的适应性，主要是在流控制周期较长且配额非常小时。group_replication_flow_control_release_percent defines how the group quota should be released when flow control no longer needs to throttle the writer members, with this percentage being the quota increase per flow control period. A value of 0 implies that once the flow control thresholds are within limits the quota is released in a single flow control iteration. The range allows the quota to be released at up to 10 times current quota, as that allows a greater degree of adaptation, mainly when the flow control period is large and the quotas are very small.

group_replication_force_members

该系统变量用于强制新的组成员身份。该系统变量的值可以在组复制运行时更改，并且更改会立即生效。您只需在要保持在组中的一个组成员上设置该系统变量的值即可。有关可能需要强制新的组成员身份的情况及使用此系统变量时应遵循的程序的详细信息，请参阅 第 20.7.8 节，“处理网络分区和法定人数丢失”。This system variable is used to force a new group membership. The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately. You only need to set the value of the system variable on one of the group members that is to remain in the group. For details of the situation in which you might need to force a new group membership, and a procedure to follow when using this system variable, see Section 20.7.8, “Handling a Network Partition and Loss of Quorum”.

group_replication_force_members 指定一个以逗号分隔的对等地址列表，例如 host1:port1,host2:port2。任何未包含在列表中的现有成员将不会接收组的新视图，并且会被阻止。对于每个要继续作为成员的现有成员，您必须包含 IP 地址或主机名以及端口，它们在每个成员的 group_replication_local_address 系统变量中给出。IPv6 地址必须用方括号括起来。例如:group_replication_force_members specifies a list of peer addresses as a comma separated list, such as host1:port1,host2:port2. Any existing members that are not included in the list do not receive a new view of the group and are blocked. For each existing member that is to continue as a member, you must include the IP address or host name and the port, as they are given in the group_replication_local_address system variable for each member. An IPv6 address must be specified in square brackets. For example:

"198.51.100.44:33061,[2001:db8:85a3:8d3:1319:8a2e:370:7348]:33061,example.org:33061"

Group Replication 的组通信引擎 (XCom) 会检查所提供的 IP 地址是否为有效格式，并检查您是否包含了任何当前无法访问的组成员。否则，新配置将无法验证，因此您必须小心只包含在线且可以访问的组成员。列表中任何不正确的值或无效的主机名都可能导致组因配置无效而被阻塞。The group communication engine for Group Replication (XCom) checks that the supplied IP addresses are in a valid format, and checks that you have not included any group members that are currently unreachable. Otherwise, the new configuration is not validated, so you must be careful to include only online servers that are reachable members of the group. Any incorrect values or invalid host names in the list could cause the group to be blocked with an invalid configuration.

在强制新的成员配置之前，确保要排除的服务器已经关闭是非常重要的。如果没有，请在继续操作前将它们关闭。仍然在线的组成员可以自动形成新的配置，如果这种情况已经发生，再强制一个新的配置可能会为组创建一个人为的分裂脑 (split-brain) 情况。It is important before forcing a new membership configuration to ensure that the servers to be excluded have been shut down. If they are not, shut them down before proceeding. Group members that are still online can automatically form new configurations, and if this has already taken place, forcing a further new configuration could create an artificial split-brain situation for the group.

在您使用 group_replication_force_members 系统变量成功强制新的群组成员并解除群组阻塞后，请确保清除该系统变量。group_replication_force_members 必须为空，才能执行 START GROUP_REPLICATION 语句。After you have used the group_replication_force_members system variable to successfully force a new group membership and unblock the group, ensure that you clear the system variable. group_replication_force_members must be empty in order to issue a START GROUP_REPLICATION statement.

group_replication_group_name

在组复制运行时，该系统变量的值无法更改。The value of this system variable cannot be changed while Group Replication is running.

group_replication_group_name 指定该服务器实例所属的组名称，该名称必须是有效的 UUID。该 UUID 构成 GTID 的一部分，当组成员从客户端接收到事务以及组成员内部生成的视图更改事件写入二进制日志时将使用该 UUID。group_replication_group_name specifies the name of the group which this server instance belongs to, which must be a valid UUID. This UUID forms part of the GTIDs that are used when transactions received by group members from clients, and view change events that are generated internally by the group members, are written to the binary log.

group_replication_group_seeds

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_group_seeds 是一个组成员列表，新加入的成员可以连接这些成员以获取所有当前组成员的详细信息。新加入的成员使用这些详细信息选择并连接到一个组成员，以获取与组同步所需的数据。该列表由每个包含的种子成员的单个内部网络地址或主机名组成，这些地址或主机名是在种子成员的 group_replication_local_address 系统变量中配置的（而不是种子成员的 SQL 客户端连接，如 MySQL Server 的 hostname 和 port 系统变量所指定）。种子成员的地址以逗号分隔的列表指定，例如 host1:port1,host2:port2。IPv6 地址必须用方括号括起来。例如：group_replication_group_seeds is a list of group members to which a joining member can connect to obtain details of all the current group members. The joining member uses these details to select and connect to a group member to obtain the data needed for synchrony with the group. The list consists of a single internal network address or host name for each included seed member, as configured in the seed member's group_replication_local_address system variable (not the seed member's SQL client connection, as specified by MySQL Server's hostname and port system variables). The addresses of the seed members are specified as a comma separated list, such as host1:port1,host2:port2. An IPv6 address must be specified in square brackets. For example:

group_replication_group_seeds= "198.51.100.44:33061,[2001:db8:85a3:8d3:1319:8a2e:370:7348]:33061, example.org:33061"

请注意，您为此变量指定的值在发出 START GROUP_REPLICATION 语句并且群组通信系统 (GCS) 可用之前不会进行验证。Note that the value you specify for this variable is not validated until a START GROUP_REPLICATION statement is issued and the Group Communication System (GCS) is available.

通常此列表包含群组的所有成员，但您可以选择群组成员的子集作为种子。列表中必须至少包含一个有效的成员地址。每个地址在启动群组复制时会进行验证。如果列表中不包含任何有效的成员地址，发出 START GROUP_REPLICATION 将失败。Usually this list consists of all members of the group, but you can choose a subset of the group members to be seeds. The list must contain at least one valid member address. Each address is validated when starting Group Replication. If the list does not contain any valid member addresses, issuing START GROUP_REPLICATION fails.

当一个服务器加入复制组时，它会尝试连接其 group_replication_group_seeds 系统变量中列出的第一个种子成员。如果连接被拒绝，加入的成员会按顺序尝试连接列表中的其他种子成员。如果加入的成员连接到一个种子成员，但未因此被添加到复制组中（例如，因为该种子成员的允许列表中没有加入成员的地址而关闭了连接），加入的成员会继续按顺序尝试列表中剩余的种子成员。When a server is joining a replication group, it attempts to connect to the first seed member listed in its group_replication_group_seeds system variable. If the connection is refused, the joining member tries to connect to each of the other seed members in the list in order. If the joining member connects to a seed member but does not get added to the replication group as a result (for example, because the seed member does not have the joining member's address in its allowlist and closes the connection), the joining member continues to try the remaining seed members in the list in order.

加入的成员必须使用与种子成员在 group_replication_group_seeds 选项中公告的相同协议（IPv4 或 IPv6）与种子成员进行通信。为了满足组复制的 IP 地址权限要求，种子成员上的允许列表必须包括为加入成员提供的、与种子成员提供的协议对应的 IP 地址，或者能够解析为该协议地址的主机名。除了加入成员的 group_replication_local_address 外，如果该地址的协议与种子成员公告的协议不匹配，该地址或主机名也必须被设置并允许使用。如果加入成员没有适用于相应协议的允许地址，其连接尝试将被拒绝。更多信息，请参阅 第 20.6.4 节，“组复制 IP 地址权限”。A joining member must communicate with the seed member using the same protocol (IPv4 or IPv6) that the seed member advertises in the group_replication_group_seeds option. For the purpose of IP address permissions for Group Replication, the allowlist on the seed member must include an IP address for the joining member for the protocol offered by the seed member, or a host name that resolves to an address for that protocol. This address or host name must be set up and permitted in addition to the joining member's group_replication_local_address if the protocol for that address does not match the seed member's advertised protocol. If a joining member does not have a permitted address for the appropriate protocol, its connection attempt is refused. For more information, see Section 20.6.4, “Group Replication IP Address Permissions”.

group_replication_gtid_assignment_block_size

group_replication_gtid_assignment_block_size 指定为每个组成员保留的连续 GTID 数量。每个成员使用自己的区块，并在需要时预留更多。group_replication_gtid_assignment_block_size specifies the number of consecutive GTIDs that are reserved for each group member. Each member consumes its own blocks and reserves more when needed.

此系统变量是一个组范围的配置设置。它在所有组成员上必须具有相同的值，组复制运行时无法更改，并且需要对整个组进行完全重启（由启用了 group_replication_bootstrap_group=ON 的服务器引导）才能使值更改生效。有关如何在事务已执行并认证的情况下安全引导组的说明，请参阅 第 20.5.2 节，“重启一个组”。This system variable is a group-wide configuration setting. It must have the same value on all group members, cannot be changed while Group Replication is running, and requires a full reboot of the group (a bootstrap by a server with group_replication_bootstrap_group=ON) in order for the value change to take effect. For instructions to safely bootstrap a group where transactions have been executed and certified, see Section 20.5.2, “Restarting a Group”.

如果该组为此系统变量设置了值，而加入的成员为该系统变量设置了不同的值，则加入的成员在将值更改为匹配之前无法加入该组。如果组成员为此系统变量设置了值，而加入的成员不支持该系统变量，则它无法加入该组。If the group has a value set for this system variable, and a joining member has a different value set for the system variable, the joining member cannot join the group until the value is changed to match. If the group members have a value set for this system variable, and the joining member does not support the system variable, it cannot join the group.

group_replication_ip_allowlist

group_replication_ip_allowlist 指定允许连接到该组的主机。当组使用 XCom 通信栈时（group_replication_communication_stack=XCOM），允许列表用于控制对该组的访问。当组使用 MySQL 通信栈时（group_replication_communication_stack=MYSQL），使用用户认证来控制对该组的访问，而允许列表不使用，即使设置也会被忽略。group_replication_ip_allowlist specifies which hosts are permitted to connect to the group. When the XCom communication stack is in use for the group (group_replication_communication_stack=XCOM), the allowlist is used to control access to the group. When the MySQL communication stack is in use for the group (group_replication_communication_stack=MYSQL), user authentication is used to control access to the group, and the allowlist is not used and is ignored if set.

您为每个组成员在 group_replication_local_address 指定的地址，必须在复制组中的其他服务器上允许。请注意，您为此变量指定的值在发出 START GROUP_REPLICATION 语句并且群组通信系统 (GCS) 可用之前不会进行验证。The address that you specify for each group member in group_replication_local_address must be permitted on the other servers in the replication group. Note that the value you specify for this variable is not validated until a START GROUP_REPLICATION statement is issued and the Group Communication System (GCS) is available.

默认情况下，此系统变量设置为 AUTOMATIC，允许来自主机上活动的私有子网的连接。Group Replication 的组通信引擎（XCom）会自动扫描主机上的活动接口，并识别具有私有子网地址的接口。这些地址以及 IPv4 和 IPv6 的 localhost IP 地址用于创建 Group Replication 允许列表。有关自动允许地址的范围列表，请参见 第 20.6.4 节，“Group Replication IP Address Permissions”。By default, this system variable is set to AUTOMATIC, which permits connections from private subnetworks active on the host. The group communication engine for Group Replication (XCom) automatically scans active interfaces on the host, and identifies those with addresses on private subnetworks. These addresses and the localhost IP address for IPv4 and IPv6 are used to create the Group Replication allowlist. For a list of the ranges from which addresses are automatically permitted, see Section 20.6.4, “Group Replication IP Address Permissions”.

私人地址的自动允许列表不能用于来自私人网络外部服务器的连接。对于在不同机器上的服务器实例之间的组复制连接，您必须提供公共 IP 地址，并将其作为显式允许列表指定。如果您为允许列表指定了任何条目，则私人地址不会自动添加，因此如果您使用其中的任何一个，必须显式指定它们。localhost IP 地址会自动添加。The automatic allowlist of private addresses cannot be used for connections from servers outside the private network. For Group Replication connections between server instances that are on different machines, you must provide public IP addresses and specify these as an explicit allowlist. If you specify any entries for the allowlist, the private addresses are not added automatically, so if you use any of these, you must specify them explicitly. The localhost IP addresses are added automatically.

作为group_replication_ip_allowlist选项的值，您可以指定以下任意组合：As the value of the group_replication_ip_allowlist option, you can specify any combination of the following:

主机名可以解析为 IPv4 地址、IPv6 地址或两者兼有。如果主机名同时解析为 IPv4 和 IPv6 地址，则 Group Replication 连接始终使用 IPv4 地址。您可以将 CIDR 表示法与主机名或 IP 地址结合使用，以允许具有特定网络前缀的一组 IP 地址，但您应确保指定子网中的所有 IP 地址都在您的控制之下。Host names can resolve to IPv4 addresses, IPv6 addresses, or both. If a host name resolves to both an IPv4 and an IPv6 address, the IPv4 address is always used for Group Replication connections. You can use CIDR notation in combination with host names or IP addresses to permit a block of IP addresses with a particular network prefix, but you should ensure that all the IP addresses in the specified subnet are under your control.

允许列表中的每个条目必须用逗号分隔。例如：A comma must separate each entry in the allowlist. For example:

"192.0.2.21/24,198.51.100.44,203.0.113.0/24,2001:db8:85a3:8d3:1319:8a2e:370:7348,example.org,www.example.com/24"

如果组的任何种子成员在 group_replication_group_seeds 选项中使用 IPv6 地址列出，而加入的成员使用 IPv4 group_replication_local_address，或者反之，则必须为加入的成员设置并允许种子成员提供协议的备用地址（或解析到该协议地址的主机名）。更多信息，请参阅 第 20.6.4 节，“组复制 IP 地址权限”。If any of the seed members for the group are listed in the group_replication_group_seeds option with an IPv6 address when a joining member has an IPv4 group_replication_local_address, or the reverse, you must also set up and permit an alternative address for the joining member for the protocol offered by the seed member (or a host name that resolves to an address for that protocol). For more information, see Section 20.6.4, “Group Replication IP Address Permissions”.

根据您的安全需求，可以为不同的组成员配置不同的允许列表，例如，为了保持不同子网的独立性。然而，当组重新配置时，这可能会引发问题。如果没有特定的安全需求，建议在组的所有成员上使用相同的允许列表。更多详情，请参见 第 20.6.4 节，“群组复制 IP 地址权限”。It is possible to configure different allowlists on different group members according to your security requirements, for example, in order to keep different subnets separate. However, this can cause issues when a group is reconfigured. If you do not have a specific security requirement to do otherwise, use the same allowlist on all members of a group. For more details, see Section 20.6.4, “Group Replication IP Address Permissions”.

对于主机名，只有在另一台服务器发出连接请求时才会进行名称解析。无法解析的主机名不会被考虑进行允许列表验证，并且会向错误日志写入警告信息。对于已解析的主机名，将进行正向确认的反向 DNS (FCrDNS) 验证。For host names, name resolution takes place only when a connection request is made by another server. A host name that cannot be resolved is not considered for allowlist validation, and a warning message is written to the error log. Forward-confirmed reverse DNS (FCrDNS) verification is carried out for resolved host names.

group_replication_local_address

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_local_address 设置成员提供给其他成员连接的网络地址，格式为 host:port 字符串。该地址必须对组内所有成员可达，因为它被组通信引擎用于 Group Replication（XCom，一种 Paxos 变体）在远程 XCom 实例之间进行 TCP 通信。如果您使用 MySQL 通信栈在成员之间建立组通信连接（group_replication_communication_stack = MYSQL），则该地址必须是 MySQL 服务器监听的 IP 地址和端口之一，这些由服务器的 bind_address 系统变量指定。group_replication_local_address sets the network address which the member provides for connections from other members, specified as a host:port formatted string. This address must be reachable by all members of the group because it is used by the group communication engine for Group Replication (XCom, a Paxos variant) for TCP communication between remote XCom instances. If you are using the MySQL communication stack to establish group communication connections between members (group_replication_communication_stack = MYSQL), the address must be one of the IP addresses and ports where MySQL Server is listening on, as specified by the bind_address system variable for the server.

在 group_replication_local_address 中指定的地址或主机名被组复制用作复制组中成员的唯一标识符。只要主机名或 IP 地址不同，你可以为复制组的所有成员使用相同的端口；只要端口不同，你也可以为所有成员使用相同的主机名或 IP 地址。group_replication_local_address 的推荐端口是 33061。请注意，直到执行 START GROUP_REPLICATION 语句并且组通信系统 (GCS) 可用后，才会验证你为此变量指定的值。The address or host name that you specify in group_replication_local_address is used by Group Replication as the unique identifier for a group member within the replication group. You can use the same port for all members of a replication group as long as the host names or IP addresses are all different, and you can use the same host name or IP address for all members as long as the ports are all different. The recommended port for group_replication_local_address is 33061. Note that the value you specify for this variable is not validated until the START GROUP_REPLICATION statement is issued and the Group Communication System (GCS) is available.

由 group_replication_local_address 配置的网络地址必须能够被所有组成员解析。例如，如果每个服务器实例位于具有固定网络地址的不同机器上，你可以使用机器的 IP 地址，例如 10.0.0.1。如果使用主机名，则必须使用完全限定的名称，并确保其可以通过 DNS、正确配置的 /etc/hosts 文件或其他名称解析过程解析。IPv6 地址必须用方括号括起来以区分端口号，例如：The network address configured by group_replication_local_address must be resolvable by all group members. For example, if each server instance is on a different machine with a fixed network address, you could use the IP address of the machine, such as 10.0.0.1. If you use a host name, you must use a fully qualified name, and ensure it is resolvable through DNS, correctly configured /etc/hosts files, or other name resolution processes. An IPv6 address must be specified in square brackets in order to distinguish the port number, for example:

group_replication_local_address= "[2001:db8:85a3:8d3:1319:8a2e:370:7348]:33061"

如果指定为服务器实例的组复制本地地址的主机名既解析为 IPv4 地址又解析为 IPv6 地址，则组复制连接始终使用 IPv4 地址。有关组复制对 IPv6 网络的支持以及对同时使用 IPv4 和 IPv6 成员的复制组的更多信息，请参见 第 20.5.5 节，“支持 IPv6 及混合 IPv6 和 IPv4 组”。If a host name specified as the Group Replication local address for a server instance resolves to both an IPv4 and an IPv6 address, the IPv4 address is always used for Group Replication connections. For more information on Group Replication support for IPv6 networks and on replication groups with a mix of members using IPv4 and members using IPv6, see Section 20.5.5, “Support For IPv6 And For Mixed IPv6 And IPv4 Groups”.

如果您使用 XCom 通信栈在成员之间建立组通信连接（group_replication_communication_stack = XCOM），则必须将您在 group_replication_local_address 中为每个组成员指定的地址添加到复制组中其他服务器的 group_replication_ip_allowlist 系统变量列表中。当组中使用 XCom 通信栈时，允许列表用于控制对组的访问。当组中使用 MySQL 通信栈时，使用用户身份验证来控制对组的访问，而允许列表不会被使用，即使设置了也会被忽略。如果组的任何种子成员在 group_replication_group_seeds 中被列为 IPv6 地址，而该成员具有 IPv4 的 group_replication_local_address，或者反之，您还必须为此成员设置并允许所需协议的备用地址（或解析为该协议地址的主机名）。有关更多信息，请参见 第 20.6.4 节，“组复制 IP 地址权限”。If you are using the XCom communication stack to establish group communication connections between members (group_replication_communication_stack = XCOM), the address that you specify for each group member in group_replication_local_address must be added to the list for the group_replication_ip_allowlist system variable on the other servers in the replication group. When the XCom communication stack is in use for the group, the allowlist is used to control access to the group. When the MySQL communication stack is in use for the group, user authentication is used to control access to the group, and the allowlist is not used and is ignored if set. If any of the seed members for the group are listed in group_replication_group_seeds with an IPv6 address when this member has an IPv4 group_replication_local_address, or the reverse, you must also set up and permit an alternative address for this member for the required protocol (or a host name that resolves to an address for that protocol). For more information, see Section 20.6.4, “Group Replication IP Address Permissions”.

group_replication_member_expel_timeout

在组复制运行期间，可以更改此系统变量的值，更改会立即生效。每当组复制检查超时时，都会读取该系统变量的当前值。并非所有组成员必须具有相同的设置，但建议这样做以避免意外驱逐。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately. The current value of the system variable is read whenever Group Replication checks the timeout. It is not mandatory for all members of a group to have the same setting, but it is recommended in order to avoid unexpected expulsions.

group_replication_member_expel_timeout 指定了 Group Replication 组成员在创建怀疑后等待的时间（以秒为单位），在将被怀疑失败的成员从组中驱逐之前。创建怀疑之前的初始 5 秒检测期不计入此时间。group_replication_member_expel_timeout 的默认值为 5，这意味着在 5 秒检测期之后，怀疑成员可能在 5 秒后被驱逐。group_replication_member_expel_timeout specifies the period of time in seconds that a Group Replication group member waits after creating a suspicion, before expelling from the group the member suspected of having failed. The initial 5-second detection period before a suspicion is created does not count as part of this time. The value of group_replication_member_expel_timeout defaults to 5, meaning that a suspected member is liable for expulsion 5 seconds after the 5-second detection period.

在组成员上更改 group_replication_member_expel_timeout 的值会立即对该组成员的现有和将来的怀疑生效。因此，您可以将此用作强制怀疑超时并驱逐被怀疑成员的方法，从而允许更改组配置。有关更多信息，请参阅 第 20.7.7.1 节，“驱逐超时”。Changing the value of group_replication_member_expel_timeout on a group member takes effect immediately for existing as well as future suspicions on that group member. You can therefore use this as a method to force a suspicion to time out and expel a suspected member, allowing changes to the group configuration. For more information, see Section 20.7.7.1, “Expel Timeout”.

增加group_replication_member_expel_timeout的值可以帮助避免在较慢或不稳定的网络上，或在预期的短暂网络中断或机器减速情况下的不必要驱逐。如果被怀疑的成员在怀疑超时之前重新激活，它将应用由其他组成员缓冲的所有消息，并进入ONLINE状态，无需操作员干预。您可以指定最长为 3600 秒（1 小时）的超时时间。确保 XCom 的消息缓存足够大以容纳在您指定的时间段内预计的消息量，加上最初的 5 秒检测期，否则成员将无法重新连接。您可以使用group_replication_message_cache_size系统变量调整缓存大小限制。有关更多信息，请参见第 20.7.6 节，“XCom 缓存管理”。Increasing the value of group_replication_member_expel_timeout can help to avoid unnecessary expulsions on slower or less stable networks, or in the case of expected transient network outages or machine slowdowns. If a suspect member becomes active again before the suspicion times out, it applies all the messages that were buffered by the remaining group members and enters ONLINE state, without operator intervention. You can specify a timeout value up to a maximum of 3600 seconds (1 hour). It is important to ensure that XCom's message cache is sufficiently large to contain the expected volume of messages in your specified time period, plus the initial 5-second detection period, otherwise members are unable to reconnect. You can adjust the cache size limit using the group_replication_message_cache_size system variable. For more information, see Section 20.7.6, “XCom Cache Management”.

如果超时被超过，嫌疑成员在怀疑超时后立即有被开除的责任。如果成员能够恢复通信并收到一个它被开除的视图，并且该成员已将 group_replication_autorejoin_tries 系统变量设置为指定自动重新加入尝试的次数，它将按指定次数尝试在超级只读模式下重新加入群组。如果成员没有指定任何自动重新加入尝试，或者已用尽指定次数的尝试，它将遵循系统变量 group_replication_exit_state_action 指定的操作。If the timeout is exceeded, the suspect member is liable for expulsion immediately after the suspicion times out. If the member is able to resume communications and receives a view where it is expelled, and the member has the group_replication_autorejoin_tries system variable set to specify a number of auto-rejoin attempts, it proceeds to make the specified number of attempts to rejoin the group while in super read only mode. If the member does not have any auto-rejoin attempts specified, or if it has exhausted the specified number of attempts, it follows the action specified by the system variable group_replication_exit_state_action.

有关使用 group_replication_member_expel_timeout 设置的更多信息，请参见 第 20.7.7.1 节，“驱逐超时”。对于在此系统变量不可用时避免不必要驱逐的替代缓解策略，请参见 第 20.3.2 节，“组复制限制”。For more information on using the group_replication_member_expel_timeout setting, see Section 20.7.7.1, “Expel Timeout”. For alternative mitigation strategies to avoid unnecessary expulsions where this system variable is not available, see Section 20.3.2, “Group Replication Limitations”.

group_replication_member_weight

在组复制运行时可以更改此系统变量的值，并且更改会立即生效。在发生故障转移时，会读取该系统变量的当前值。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately. The system variable's current value is read when a failover situation occurs.

group_replication_member_weight 指定可以分配给成员的百分比权重，以在故障转移时影响成员被选为主节点的机会，例如当现有主节点离开单主组时。为成员分配数值权重，以确保特定成员被选举，例如在计划的主节点维护期间，或者在故障转移时确保某些硬件被优先考虑。group_replication_member_weight specifies a percentage weight that can be assigned to members to influence the chance of the member being elected as primary in the event of failover, for example when the existing primary leaves a single-primary group. Assign numeric weights to members to ensure that specific members are elected, for example during scheduled maintenance of the primary or to ensure certain hardware is prioritized in the event of failover.

对于配置如下成员的组：For a group with members configured as follows:

在新主节点选举期间，上述成员将按 member-2，member-3，member-4，和 member-1 的顺序排序。这将导致在故障切换事件中 member-2 被选为新的主节点。更多信息，请参见 20.1.3.1 节，“单主模式”。during election of a new primary the members above would be sorted as member-2, member-3, member-4, and member-1. This results in member-2 being chosen as the new primary in the event of failover. For more information, see Section 20.1.3.1, “Single-Primary Mode”.

group_replication_message_cache_size

这个系统变量在所有组成员中应具有相同的值。此系统变量的值可以在组复制运行时更改。更改在每个组成员上在停止并重新启动组复制后生效。在此过程中，系统变量的值允许在组成员之间有所不同，但在发生断开连接的情况下，成员可能无法重新连接。This system variable should have the same value on all group members. The value of this system variable can be changed while Group Replication is running. The change takes effect on each group member after you stop and restart Group Replication on the member. During this process, the value of the system variable is permitted to differ between group members, but members might be unable to reconnect in the event of a disconnection.

group_replication_message_cache_size 设置 Group Replication (XCom) 组通信引擎中消息缓存可用的最大内存量。XCom 消息缓存保存组成员之间在一致性协议中交换的消息（及其元数据）。消息缓存的功能之一是用于重新加入组的成员在一段无法与其他组成员通信的时间后，恢复丢失的消息。group_replication_message_cache_size sets the maximum amount of memory that is available for the message cache in the group communication engine for Group Replication (XCom). The XCom message cache holds messages (and their metadata) that are exchanged between the group members as a part of the consensus protocol. Among other functions, the message cache is used for recovery of missed messages by members that reconnect with the group after a period where they were unable to communicate with the other group members.

group_replication_member_expel_timeout 系统变量决定了除了最初的 5 秒检测期之外，允许成员返回群组而不被驱逐的等待时间（最长可达一小时）。XCom 消息缓存的大小应根据此时间段内预期的消息量进行设置，以确保包含成员成功返回所需的所有未接收消息。默认值是在 5 秒检测期之后等待 5 秒，总时间为 10 秒。The group_replication_member_expel_timeout system variable determines the waiting period (up to an hour) that is allowed in addition to the initial 5-second detection period for members to return to the group rather than being expelled. The size of the XCom message cache should be set with reference to the expected volume of messages in this time period, so that it contains all the missed messages required for members to return successfully. The default is a 5-second waiting period after the 5-second detection period, for a total time period of 10 seconds.

确保您的系统中有足够的内存来满足您选择的缓存大小限制，同时要考虑服务器其他缓存和对象池的大小。默认设置为 1073741824 字节（1 GB）。最小设置为 134217728 字节（128 MB），使得可以在可用内存有限的主机上进行部署，并且在组成员的网络连接良好时，最小化临时连接丢失的频率和持续时间。请注意，使用 group_replication_message_cache_size 设置的限制仅适用于缓存中存储的数据，而缓存结构则需要额外的 50 MB 内存。Ensure that sufficient memory is available on your system for your chosen cache size limit, considering the size of the server's other caches and object pools. The default setting is 1073741824 bytes (1 GB). The minimum setting of 134217728 bytes (128 MB) enables deployment on a host that has a restricted amount of available memory, and good network connectivity to minimize the frequency and duration of transient losses of connectivity for group members. Note that the limit set using group_replication_message_cache_size applies only to the data stored in the cache, and the cache structures require an additional 50 MB of memory.

缓存大小限制可以在运行时动态增加或减少。如果您减少缓存大小限制，XCom 会删除已决定并已传递的最旧条目，直到当前大小低于限制。当消息缓存中可能需要用于恢复的、当前不可达的成员所需的消息被删除时，组复制的组通信系统（GCS）会通过警告消息提醒您。有关调整消息缓存大小的更多信息，请参阅 第 20.7.6 节，“XCom 缓存管理”。The cache size limit can be increased or reduced dynamically at runtime. If you reduce the cache size limit, XCom removes the oldest entries that have been decided and delivered until the current size is below the limit. Group Replication's Group Communication System (GCS) alerts you, by a warning message, when a message that is likely to be needed for recovery by a member that is currently unreachable is removed from the message cache. For more information on tuning the message cache size, see Section 20.7.6, “XCom Cache Management”.

group_replication_paxos_single_leader

group_replication_paxos_single_leader 使群组通信引擎在单主模式下可以使用单一共识领导者运行。默认设置为 OFF 时，此行为被禁用，群组中的每个成员都充当领导者，这也是该系统变量引入之前版本的行为。当将此变量设置为 ON 时，群组通信引擎可以使用单一领导者来推动共识。在单主模式下使用单一共识领导者可以提高性能和弹性，特别是在群组的一些从属成员当前无法访问的情况下。有关更多信息，请参见 第 20.7.3 节，“单一共识领导者”。group_replication_paxos_single_leader enables the group communication engine to operate with a single consensus leader when the group is in single-primary mode. With the default setting OFF, this behavior is disabled, and every member of the group is used as a leader, which is the behavior in releases before this system variable was available. When this variable is set to ON, the group communication engine can use a single leader to drive consensus. Operating with a single consensus leader improves performance and resilience in single-primary mode, particularly when some of the group’s secondary members are currently unreachable. For more information, see Section 20.7.3, “Single Consensus Leader”.

为了让组通信引擎使用单一共识领导者，组的通信协议版本必须是 MySQL 8.0.27 或更高版本。使用 group_replication_get_communication_protocol() 获取组的通信协议版本。如果使用的是低版本，组将无法使用此行为。如果所有组成员都支持，可以使用 group_replication_set_communication_protocol() 将通信协议设置为更高版本。有关更多信息，请参见 第 20.5.1.4 节，“设置组的通信协议版本”。In order for the group communication engine to use a single consensus leader, the group's communication protocol version must be MySQL 8.0.27 or later. Use group_replication_get_communication_protocol() to obtain the group's communication protocol version. If a lower version is in use, the group cannot use this behavior. You can use group_replication_set_communication_protocol() to set the communication protocol to a higher version if all group members support it. For more information, see Section 20.5.1.4, “Setting a Group's Communication Protocol Version”.

此系统变量是一个组范围的配置设置。它在所有组成员上必须具有相同的值，组复制运行时无法更改，并且需要对整个组进行完全重启（由启用了 group_replication_bootstrap_group=ON 的服务器引导）才能使值更改生效。有关如何在事务已执行并认证的情况下安全引导组的说明，请参阅 第 20.5.2 节，“重启一个组”。This system variable is a group-wide configuration setting. It must have the same value on all group members, cannot be changed while Group Replication is running, and requires a full reboot of the group (a bootstrap by a server with group_replication_bootstrap_group=ON) in order for the value change to take effect. For instructions to safely bootstrap a group where transactions have been executed and certified, see Section 20.5.2, “Restarting a Group”.

如果该组为此系统变量设置了值，而加入的成员为该系统变量设置了不同的值，则加入的成员在将值更改为匹配之前无法加入该组。如果组成员为此系统变量设置了值，而加入的成员不支持该系统变量，则它无法加入该组。If the group has a value set for this system variable, and a joining member has a different value set for the system variable, the joining member cannot join the group until the value is changed to match. If the group members have a value set for this system variable, and the joining member does not support the system variable, it cannot join the group.

性能模式表 replication_group_communication_information 的 WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE 列显示该组是否支持使用单个领导者，即使查询的成员上 group_replication_paxos_single_leader 当前设置为 OFF。如果该组在启动时将 group_replication_paxos_single_leader 设置为 ON，并且其通信协议版本为 MySQL 8.0.27 或更高版本，则该列值为 1。The WRITE_CONSENSUS_SINGLE_LEADER_CAPABLE column of the Performance Schema table replication_group_communication_information shows whether the group supports the use of a single leader, even if group_replication_paxos_single_leader is currently set to OFF on the queried member. The column value is 1 if the group was started with group_replication_paxos_single_leader set to ON, and its communication protocol version is MySQL 8.0.27 or later.

group_replication_poll_spin_loops

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_poll_spin_loops 指定组通信线程在等待更多传入网络消息之前，等待通信引擎互斥锁释放的次数。group_replication_poll_spin_loops specifies the number of times the group communication thread waits for the communication engine mutex to be released before the thread waits for more incoming network messages.

group_replication_preemptive_garbage_collection

在单主模式（仅）中启用抢占式垃圾回收，仅保留那些尚未在数据库中提交的事务的写集。Enable preemptive garbage collection in single-primary mode (only), keeping only the write sets for those transactions that have not yet been committed in the database.

在单主模式下，可以比在多主模式下更早地清理给定事务的写集；这是因为冲突在事务执行期间由服务器中的数据库锁管理器检测和处理；因此，写集仅用于计算事务之间的依赖关系，而不用于冲突检测。这意味着，一旦事务在组复制事务依赖和冲突检测模块中被跟踪，它所属的写集就可以被清理。In single-primary mode it is possible to clean up write sets for a given transaction earlier than in multi-primary mode; this is because conflicts are detected and handled by the database lock manager in the server while transactions are executing; thus, the write sets are useful only for calculating dependencies between transactions, and not for conflict detection. This means that write sets can be cleaned up as soon as the transaction to which they belong is tracked in the Group Replication transaction dependency and conflict detection module.

当启用 group_replication_preemptive_garbage_collection 时，对写集进行的积极清理具有以下效果：The aggressive purging of write sets which is performed when group_replication_preemptive_garbage_collection is enabled has the following effects:

只有在 Group Replication 未运行时，才能更改group_replication_preemptive_garbage_collection的值，并且对以多主模式运行的组没有影响。此外，当启用该系统变量时，无法在多主模式和单主模式之间切换（参见第 20.5.1.2 节，“更改组模式”）。The value of group_replication_preemptive_garbage_collection can be changed only when Group Replication is not running, and has no effect on a group running in multi-primary mode. In addition, when this system variable is enabled, it is not possible to change between multi-primary mode and single-primary mode (see Section 20.5.1.2, “Changing the Group Mode”).

group_replication_preemptive_garbage_collection 必须在所有组成员上设置为相同的值。新加入成员的 group_replication_preemptive_garbage_collection 值必须与组中所有当前成员的值相同，否则它无法加入。group_replication_preemptive_garbage_collection must be set to the same value on all group members. A new joiner's group_replication_preemptive_garbage_collection value must be the same as those of all the group's current members, else it cannot join.

运行 MySQL 8.4.0 之前版本的组成员不会发送 group_replication_preemptive_garbage_collection 值；在这种情况下，该值被视为 OFF。A group member running a version of MySQL previous to 8.4.0 sends no group_replication_preemptive_garbage_collection value; in such cases, the value is considered to be OFF.

group_replication_preemptive_garbage_collection_rows_threshold

当在单主模式下启用抢占式垃圾回收（group_replication_preemptive_garbage_collection 为 ON）时，这是触发其使用所需的认证信息行数。When preemptive garbage collection in single-primary mode is enabled (group_replication_preemptive_garbage_collection is ON), this is the number of rows of certification information needed to trigger its use.

此变量对运行在多主模式的组没有影响。This variable has no effect on a group running in multi-primary mode.

group_replication_recovery_compression_algorithms

group_replication_recovery_compression_algorithms 指定允许用于组复制分布式恢复连接以从捐赠者的二进制日志进行状态传输的压缩算法。可用的算法与 protocol_compression_algorithms 系统变量相同。有关更多信息，请参见 第 6.2.8 节，“连接压缩控制”。group_replication_recovery_compression_algorithms specifies the compression algorithms permitted for Group Replication distributed recovery connections for state transfer from a donor's binary log. The available algorithms are the same as for the protocol_compression_algorithms system variable. For more information, see Section 6.2.8, “Connection Compression Control”.

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

如果服务器已设置为支持克隆（参见第 20.5.4.2 节，“分布式恢复的克隆”）且在分布式恢复期间使用远程克隆操作，则此设置不适用。对于这种状态传输方法，克隆插件的clone_enable_compression 设置适用。This setting does not apply if the server has been set up to support cloning (see Section 20.5.4.2, “Cloning for Distributed Recovery”) and a remote cloning operation is used during distributed recovery. For this method of state transfer, the clone plugin's clone_enable_compression setting applies.

group_replication_recovery_get_public_key

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_get_public_key 指定是否从源端请求用于基于 RSA 密钥对密码交换的公钥。如果 group_replication_recovery_public_key_path 设置为有效的公钥文件，它将优先于 group_replication_recovery_get_public_key。如果未在 group_replication_recovery 通道上使用 SSL 进行分布式恢复（group_replication_recovery_use_ssl=ON），并且 Group Replication 的复制用户账户使用 caching_sha2_password 插件（默认）进行认证，则此变量适用。更多详情，请参见 第 20.6.3.1.1 节“具有 Caching SHA-2 认证插件的复制用户”。group_replication_recovery_get_public_key specifies whether to request from the source the public key required for RSA key pair-based password exchange. If group_replication_recovery_public_key_path is set to a valid public key file, it takes precedence over group_replication_recovery_get_public_key. This variable applies if you are not using SSL for distributed recovery over the group_replication_recovery channel (group_replication_recovery_use_ssl=ON), and the replication user account for Group Replication authenticates with the caching_sha2_password plugin (the default). For more details, see Section 20.6.3.1.1, “Replication User With The Caching SHA-2 Authentication Plugin”.

group_replication_recovery_public_key_path

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_public_key_path 指定包含源端用于基于 RSA 密钥对的密码交换所需公钥的副本的文件路径。该文件必须是 PEM 格式。如果 group_replication_recovery_public_key_path 设置为有效的公钥文件，它优先于 group_replication_recovery_get_public_key。如果您在 group_replication_recovery 通道上不使用 SSL 进行分布式恢复（因此 group_replication_recovery_use_ssl 设置为 OFF），并且 Group Replication 的复制用户帐户使用 caching_sha2_password 插件（默认）或 sha256_password 插件（已弃用）进行身份验证，则此变量适用。（对于 sha256_password，仅当 MySQL 使用 OpenSSL 构建时，设置 group_replication_recovery_public_key_path 才适用。）更多详细信息，请参见 第 20.6.3.1.1 节，“使用 Caching SHA-2 认证插件的复制用户”。group_replication_recovery_public_key_path specifies the path name to a file containing a replica-side copy of the public key required by the source for RSA key pair-based password exchange. The file must be in PEM format. If group_replication_recovery_public_key_path is set to a valid public key file, it takes precedence over group_replication_recovery_get_public_key. This variable applies if you are not using SSL for distributed recovery over the group_replication_recovery channel (so group_replication_recovery_use_ssl is set to OFF), and the replication user account for Group Replication authenticates with the caching_sha2_password plugin (the default) or the sha256_password plugin (deprecated). (For sha256_password, setting group_replication_recovery_public_key_path applies only if MySQL was built using OpenSSL.) For more details, see Section 20.6.3.1.1, “Replication User With The Caching SHA-2 Authentication Plugin”.

group_replication_recovery_reconnect_interval

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_reconnect_interval 指定在没有在组中找到合适的捐赠者进行分布式恢复时，重连尝试之间的休眠时间（以秒为单位）。group_replication_recovery_reconnect_interval specifies the sleep time, in seconds, between reconnection attempts when no suitable donor was found in the group for distributed recovery.

group_replication_recovery_retry_count

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_retry_count 指定加入的成员在放弃之前尝试连接可用捐赠者进行分布式恢复的次数。group_replication_recovery_retry_count specifies the number of times that the member that is joining tries to connect to the available donors for distributed recovery before giving up.

group_replication_recovery_ssl_ca

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_ca 指定包含用于分布式恢复连接的受信任 SSL 证书颁发机构列表的文件路径。有关配置分布式恢复的 SSL 信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_ssl_ca specifies the path to a file that contains a list of trusted SSL certificate authorities for distributed recovery connections. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

如果此服务器已设置为支持克隆（参见 第 20.5.4.2 节，“分布式恢复克隆”），并且您已将 group_replication_recovery_use_ssl 设置为 ON，则群组复制会自动将克隆 SSL 选项 clone_ssl_ca 的设置配置为与您对 group_replication_recovery_ssl_ca 的设置匹配。If this server has been set up to support cloning (see Section 20.5.4.2, “Cloning for Distributed Recovery”), and you have set group_replication_recovery_use_ssl to ON, Group Replication automatically configures the setting for the clone SSL option clone_ssl_ca to match your setting for group_replication_recovery_ssl_ca.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_capath

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_capath 指定包含受信任 SSL 证书颁发机构证书的目录路径，用于分布式恢复连接。有关配置分布式恢复的 SSL 信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护群组通信连接”。group_replication_recovery_ssl_capath specifies the path to a directory that contains trusted SSL certificate authority certificates for distributed recovery connections. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_cert

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_cert 指定用于为分布式恢复建立安全连接的 SSL 证书文件的名称。有关配置分布式恢复 SSL 的信息，请参阅 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_ssl_cert specifies the name of the SSL certificate file to use for establishing a secure connection for distributed recovery. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

如果此服务器已设置为支持克隆（参见 第 20.5.4.2 节，“用于分布式恢复的克隆”），并且您已将 group_replication_recovery_use_ssl 设置为 ON，Group Replication 会自动将克隆 SSL 选项 clone_ssl_cert 的设置配置为与您对 group_replication_recovery_ssl_cert 的设置匹配。If this server has been set up to support cloning (see Section 20.5.4.2, “Cloning for Distributed Recovery”), and you have set group_replication_recovery_use_ssl to ON, Group Replication automatically configures the setting for the clone SSL option clone_ssl_cert to match your setting for group_replication_recovery_ssl_cert.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_cipher

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_cipher 指定用于 SSL 加密的允许密码列表。有关为分布式恢复配置 SSL 的信息，请参见 第 20.6.2 节，“使用安全套接字层（SSL）保护组通信连接”。group_replication_recovery_ssl_cipher specifies the list of permissible ciphers for SSL encryption. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_crl

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_crl 指定包含证书撤销列表文件的目录路径。有关为分布式恢复配置 SSL 的信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_ssl_crl specifies the path to a directory that contains files containing certificate revocation lists. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_crlpath

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_crlpath 指定包含证书吊销列表文件的目录路径。有关配置分布式恢复的 SSL 信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_ssl_crlpath specifies the path to a directory that contains files containing certificate revocation lists. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_key

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_key 指定用于建立安全连接的 SSL 密钥文件的名称。有关为分布式恢复配置 SSL 的信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_ssl_key specifies the name of the SSL key file to use for establishing a secure connection. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

如果此服务器已设置为支持克隆（参见 第 20.5.4.2 节，“分布式恢复克隆”），并且您已将 group_replication_recovery_use_ssl 设置为 ON，则群组复制会自动将克隆 SSL 选项 clone_ssl_key 的设置配置为与您对 group_replication_recovery_ssl_key 的设置匹配。If this server has been set up to support cloning (see Section 20.5.4.2, “Cloning for Distributed Recovery”), and you have set group_replication_recovery_use_ssl to ON, Group Replication automatically configures the setting for the clone SSL option clone_ssl_key to match your setting for group_replication_recovery_ssl_key.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_ssl_verify_server_cert

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_ssl_verify_server_cert 指定分布式恢复连接是否应检查捐赠者发送的证书中的服务器通用名称（Common Name）值。有关为分布式恢复配置 SSL 的信息，请参阅 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_ssl_verify_server_cert specifies whether the distributed recovery connection should check the server's Common Name value in the certificate sent by the donor. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_tls_ciphersuites

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_tls_ciphersuites 指定在使用 TLSv1.3 进行分布式恢复连接加密时允许的一个或多个加密套件的冒号分隔列表，并且当该服务器实例在分布式恢复连接中作为客户端（即参与成员）时使用。如果在使用 TLSv1.3 时将此系统变量设置为 NULL（如果不设置此系统变量，默认即为 NULL），则允许使用默认启用的加密套件，如 第 8.3.2 节，‘加密连接 TLS 协议和加密套件’ 所列。如果将此系统变量设置为空字符串，则不允许任何加密套件，因此不使用 TLSv1.3。有关配置分布式恢复的 SSL 信息，请参见 第 20.6.2 节，“使用安全套接字层（SSL）保护组通信连接”。group_replication_recovery_tls_ciphersuites specifies a colon-separated list of one or more permitted ciphersuites when TLSv1.3 is used for connection encryption for the distributed recovery connection, and this server instance is the client in the distributed recovery connection, that is, the joining member. If this system variable is set to NULL when TLSv1.3 is used (which is the default if you do not set the system variable), the ciphersuites that are enabled by default are allowed, as listed in Section 8.3.2, “Encrypted Connection TLS Protocols and Ciphers”. If this system variable is set to the empty string, no cipher suites are allowed, and TLSv1.3 is therefore not used. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)”, for information on configuring SSL for distributed recovery.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

group_replication_recovery_tls_version

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_tls_version 指定一个以逗号分隔的允许的 TLS 协议列表，用于在此服务器实例作为分布式恢复连接中的客户端（即加入成员）时进行连接加密。在每个分布式恢复连接中，作为客户端（加入成员）和服务器（捐赠者）的组成员会协商它们都支持的最高协议版本。group_replication_recovery_tls_version specifies a comma-separated list of one or more permitted TLS protocols for connection encryption when this server instance is the client in the distributed recovery connection, that is, the joining member. The group members involved in each distributed recovery connection as the client (joining member) and server (donor) negotiate the highest protocol version that they are both set up to support.

当组使用 MySQL 通信栈时（group_replication_communication_stack = MYSQL），此设置用于组通信连接以及分布式恢复连接的 TLS/SSL 配置。When the MySQL communication stack is in use for the group (group_replication_communication_stack = MYSQL), this setting is used for the TLS/SSL configuration for group communication connections, as well as for distributed recovery connections.

默认值为 “TLSv1.2,TLSv1.3”。确保指定的协议版本是连续的，中间不要跳过任何版本号。The default is “TLSv1.2,TLSv1.3”. Ensure that the specified protocol versions are contiguous, with no versions numbers skipped from the middle of the sequence.

有关为分布式恢复配置 SSL 的信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

group_replication_recovery_use_ssl

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_use_ssl 指定组复制成员之间的分布式恢复连接是否应使用 SSL。有关为分布式恢复配置 SSL 的信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。group_replication_recovery_use_ssl specifies whether Group Replication distributed recovery connections between group members should use SSL or not. See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for distributed recovery.

如果该服务器已设置为支持克隆（请参见第 20.5.4.2 节，“分布式恢复的克隆”），并且你将此选项设置为ON，则组复制在远程克隆操作以及从捐赠者的二进制日志进行状态传输时使用 SSL。如果你将此选项设置为OFF，组复制在远程克隆操作时不使用 SSL。If this server has been set up to support cloning (see Section 20.5.4.2, “Cloning for Distributed Recovery”), and you set this option to ON, Group Replication uses SSL for remote cloning operations as well as for state transfer from a donor's binary log. If you set this option to OFF, Group Replication does not use SSL for remote cloning operations.

group_replication_recovery_zstd_compression_level

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_recovery_zstd_compression_level 指定用于使用 zstd 压缩算法的组复制分布式恢复连接的压缩级别。允许的级别从 1 到 22，数值越大表示压缩程度越高。默认的 zstd 压缩级别为 3。对于不使用 zstd 压缩的分布式恢复连接，此变量无效。group_replication_recovery_zstd_compression_level specifies the compression level to use for Group Replication distributed recovery connections that use the zstd compression algorithm. The permitted levels are from 1 to 22, with larger values indicating increasing levels of compression. The default zstd compression level is 3. For distributed recovery connections that do not use zstd compression, this variable has no effect.

更多信息，请参阅 第 6.2.8 节，“连接压缩控制”。For more information, see Section 6.2.8, “Connection Compression Control”.

group_replication_single_primary_mode

group_replication_single_primary_mode 指示组自动选择一个服务器来处理读/写工作负载。该服务器为主服务器，其他所有服务器为从服务器。group_replication_single_primary_mode instructs the group to pick a single server automatically to be the one that handles read/write workload. This server is the primary and all others are secondaries.

此系统变量是一个组范围的配置设置。它在所有组成员上必须具有相同的值，组复制运行时无法更改，并且需要对整个组进行完全重启（由启用了 group_replication_bootstrap_group=ON 的服务器引导）才能使值更改生效。有关如何在事务已执行并认证的情况下安全引导组的说明，请参阅 第 20.5.2 节，“重启一个组”。This system variable is a group-wide configuration setting. It must have the same value on all group members, cannot be changed while Group Replication is running, and requires a full reboot of the group (a bootstrap by a server with group_replication_bootstrap_group=ON) in order for the value change to take effect. For instructions to safely bootstrap a group where transactions have been executed and certified, see Section 20.5.2, “Restarting a Group”.

如果该组为此系统变量设置了值，而加入的成员为该系统变量设置了不同的值，则加入的成员在将值更改为匹配之前无法加入该组。如果组成员为此系统变量设置了值，而加入的成员不支持该系统变量，则它无法加入该组。If the group has a value set for this system variable, and a joining member has a different value set for the system variable, the joining member cannot join the group until the value is changed to match. If the group members have a value set for this system variable, and the joining member does not support the system variable, it cannot join the group.

将此变量设置为 ON 会导致忽略对 group_replication_auto_increment_increment 的任何设置。Setting this variable ON causes any setting for group_replication_auto_increment_increment to be ignored.

在组仍在运行时，使用函数 group_replication_switch_to_single_primary_mode() 和 group_replication_switch_to_multi_primary_mode() 来更改此系统变量的值。更多信息，请参见 节 20.5.1.2，“更改组模式”。Use the functions group_replication_switch_to_single_primary_mode() and group_replication_switch_to_multi_primary_mode() to change the value of this system variable while the group is still running. For more information, see Section 20.5.1.2, “Changing the Group Mode”.

group_replication_ssl_mode

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_ssl_mode 设置 Group Replication 成员之间组通信连接的安全状态。可能的值如下：group_replication_ssl_mode sets the security state of group communication connections between Group Replication members. The possible values are as follows:

该变量在组的所有成员上应具有相同的值；否则，新成员可能无法加入。This variable should have the same value on all members of the group; otherwise, new members may be unable to join.

有关配置组通信的 SSL 信息，请参见 第 20.6.2 节，“使用安全套接字层 (SSL) 保护组通信连接”。See Section 20.6.2, “Securing Group Communication Connections with Secure Socket Layer (SSL)” for information on configuring SSL for group communication.

group_replication_start_on_boot

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_start_on_boot 指定服务器在启动时是否应自动启动组复制（ON）或不启动（OFF）。当您将此选项设置为 ON 时，使用远程克隆操作进行分布式恢复后，组复制会自动重新启动。group_replication_start_on_boot specifies whether the server should start Group Replication automatically (ON) or not (OFF) during server start. When you set this option to ON, Group Replication restarts automatically after a remote cloning operation is used for distributed recovery.

要在服务器启动时自动启动组复制，分布式恢复的用户凭据必须使用 CHANGE REPLICATION SOURCE TO 语句存储在服务器上的复制元数据仓库中。如果您希望在 START GROUP_REPLICATION 中指定用户凭据（该方法仅将用户凭据存储在内存中），请确保 group_replication_start_on_boot 设置为 OFF。To start Group Replication automatically during server start, the user credentials for distributed recovery must be stored in the replication metadata repositories on the server using the CHANGE REPLICATION SOURCE TO statement. If you prefer to specify user credentials as part of START GROUP_REPLICATION, which stores the user credentials in memory only, ensure that group_replication_start_on_boot is set to OFF.

group_replication_tls_source

此系统变量的值可以在组复制运行时更改，但更改只有在停止并重新启动组成员上的组复制后才会生效。The value of this system variable can be changed while Group Replication is running, but the change takes effect only after you stop and restart Group Replication on the group member.

group_replication_tls_source 指定 Group Replication 的 TLS 材料来源。group_replication_tls_source specifies the source of TLS material for Group Replication.

group_replication_transaction_size_limit

这个系统变量在所有组成员上应该有相同的值。该系统变量的值可以在组复制运行时更改。更改会立即在组成员上生效，并从该成员上开始的下一个事务起应用。在此过程中，系统变量的值允许在组成员之间有所不同，但某些事务可能会被拒绝。This system variable should have the same value on all group members. The value of this system variable can be changed while Group Replication is running. The change takes effect immediately on the group member, and applies from the next transaction started on that member. During this process, the value of the system variable is permitted to differ between group members, but some transactions might be rejected.

group_replication_transaction_size_limit 配置复制组接受的最大事务大小（以字节为单位）。大于此大小的事务将由接收成员回滚，并且不会广播到组中。大事务可能会给复制组带来问题，例如内存分配问题，这可能导致系统变慢，或网络带宽消耗问题，这可能会导致某个成员被怀疑发生故障，因为它正在处理大事务。group_replication_transaction_size_limit configures the maximum transaction size in bytes which the replication group accepts. Transactions larger than this size are rolled back by the receiving member and are not broadcast to the group. Large transactions can cause problems for a replication group in terms of memory allocation, which can cause the system to slow down, or in terms of network bandwidth consumption, which can cause a member to be suspected of having failed because it is busy processing the large transaction.

当此系统变量设置为 0 时，组接受的事务大小没有限制。默认值为 150000000 字节（约 143 MB）。根据您希望组能够容忍的最大消息大小调整此系统变量的值，请记住，处理事务所需的时间与其大小成正比。所有组成员上的 group_replication_transaction_size_limit 的值应相同。有关大事务的进一步缓解策略，请参见 第 20.3.2 节，“组复制限制”。When this system variable is set to 0 there is no limit to the size of transactions the group accepts. The default is 150000000 bytes (approximately 143 MB). Adjust the value of this system variable depending on the maximum message size that you need the group to tolerate, bearing in mind that the time taken to process a transaction is proportional to its size. The value of group_replication_transaction_size_limit should be the same on all group members. For further mitigation strategies for large transactions, see Section 20.3.2, “Group Replication Limitations”.

group_replication_unreachable_majority_timeout

此系统变量的值可以在组复制运行时更改，并且更改会立即生效。当发生需要该行为的问题时，会读取系统变量的当前值。The value of this system variable can be changed while Group Replication is running, and the change takes effect immediately. The current value of the system variable is read when an issue occurs that means the behavior is needed.

group_replication_unreachable_majority_timeout 指定那些遭遇网络分区而无法连接到大多数成员的成员，在离开组之前等待的秒数。在一个由 5 台服务器 (S1,S2,S3,S4,S5) 组成的组中，如果 (S1,S2) 与 (S3,S4,S5) 之间断开连接，就会出现网络分区。第一个组 (S1,S2) 现在处于少数，因为它无法联系到超过半数的组成员。当大多数组 (S3,S4,S5) 仍然运行时，少数组会等待指定的时间以重新建立网络连接。有关该场景的详细描述，请参阅 第 20.7.8 节，“处理网络分区和仲裁丢失”。group_replication_unreachable_majority_timeout specifies a number of seconds for which members that suffer a network partition and cannot connect to the majority wait before leaving the group. In a group of 5 servers (S1,S2,S3,S4,S5), if there is a disconnection between (S1,S2) and (S3,S4,S5) there is a network partition. The first group (S1,S2) is now in a minority because it cannot contact more than half of the group. While the majority group (S3,S4,S5) remains running, the minority group waits for the specified time for a network reconnection. For a detailed description of this scenario, see Section 20.7.8, “Handling a Network Partition and Loss of Quorum”.

默认情况下，group_replication_unreachable_majority_timeout 设置为 0，这意味着由于网络分区而处于少数的成员会无限期等待离开组。如果设置了超时时间，当指定时间到期时，少数成员处理的所有待处理事务都会回滚，少数分区中的服务器会进入 ERROR 状态。如果成员设置了 group_replication_autorejoin_tries 系统变量以指定自动重新加入尝试次数，它将在超级只读模式下进行指定次数的尝试以重新加入组。如果成员没有指定任何自动重新加入尝试次数，或者已用尽指定次数的尝试，它将执行系统变量 group_replication_exit_state_action 指定的操作。By default, group_replication_unreachable_majority_timeout is set to 0, which means that members that find themselves in a minority due to a network partition wait forever to leave the group. If you set a timeout, when the specified time elapses, all pending transactions processed by the minority are rolled back, and the servers in the minority partition move to the ERROR state. If a member has the group_replication_autorejoin_tries system variable set to specify a number of auto-rejoin attempts, it proceeds to make the specified number of attempts to rejoin the group while in super read only mode. If the member does not have any auto-rejoin attempts specified, or if it has exhausted the specified number of attempts, it follows the action specified by the system variable group_replication_exit_state_action.

有关使用此选项的更多信息，请参见第 20.7.7.2 节，“无法访问的多数超时”。For more information on using this option, see Section 20.7.7.2, “Unreachable Majority Timeout”.

group_replication_view_change_uuid

group_replication_view_change_uuid 指定作为由组生成的视图更改事件的 GTID 标识符中 UUID 部分的替代 UUID。替代 UUID 使这些内部生成的事务容易区分于从客户端接收到的事务。如果您的设置允许组之间的故障切换，并且您需要识别并丢弃特定于备用组的事务，这会非常有用。此系统变量的默认值为 AUTOMATIC，这意味着视图更改事件的 GTID 使用 group_replication_group_name 系统变量指定的组名，与来自客户端的事务一样。在没有此系统变量的版本中，组成员被视为具有 AUTOMATIC 值。group_replication_view_change_uuid specifies an alternative UUID to use as the UUID part of the identifier in the GTIDs for view change events generated by the group. The alternative UUID makes these internally generated transactions easy to distinguish from transactions received by the group from clients. This can be useful if your setup allows for failover between groups, and you need to identify and discard transactions that were specific to the backup group. The default value for this system variable is AUTOMATIC, meaning that the GTIDs for view change events use the group name specified by the group_replication_group_name system variable, as transactions from clients do. Group members at a release that does not have this system variable are treated as having the value AUTOMATIC.

备用 UUID 必须不同于由 group_replication_group_name 系统变量指定的组名，并且必须不同于任何组成员的服务器 UUID。它还必须不同于在该拓扑中的任何复制通道上对匿名事务应用的 GTID 中使用的任何 UUID，这些 GTID 使用 ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS 语句的 CHANGE REPLICATION SOURCE TO 选项。The alternative UUID must be different from the group name specified by the group_replication_group_name system variable, and it must be different from the server UUID of any group member. It must also be different from any UUIDs used in the GTIDs that are applied to anonymous transactions on replication channels anywhere in this topology, using the ASSIGN_GTIDS_TO_ANONYMOUS_TRANSACTIONS option of the CHANGE REPLICATION SOURCE TO statement.

此系统变量是一个组范围的配置设置。它在所有组成员上必须具有相同的值，组复制运行时无法更改，并且需要对整个组进行完全重启（由启用了 group_replication_bootstrap_group=ON 的服务器引导）才能使值更改生效。有关如何在事务已执行并认证的情况下安全引导组的说明，请参阅 第 20.5.2 节，“重启一个组”。This system variable is a group-wide configuration setting. It must have the same value on all group members, cannot be changed while Group Replication is running, and requires a full reboot of the group (a bootstrap by a server with group_replication_bootstrap_group=ON) in order for the value change to take effect. For instructions to safely bootstrap a group where transactions have been executed and certified, see Section 20.5.2, “Restarting a Group”.

如果该组为此系统变量设置了值，而加入的成员为该系统变量设置了不同的值，则加入的成员在将值更改为匹配之前无法加入该组。如果组成员为此系统变量设置了值，而加入的成员不支持该系统变量，则它无法加入该组。If the group has a value set for this system variable, and a joining member has a different value set for the system variable, the joining member cannot join the group until the value is changed to match. If the group members have a value set for this system variable, and the joining member does not support the system variable, it cannot join the group.

视图更改事件的日志记录已被恢复元数据共享取代；因此，该变量已被弃用，并且可能在未来版本的 MySQL 中移除。Logging of view change events is replaced by sharing of recovery metadata; thus, this variable is deprecated, and subject to removal in a future version of MySQL.