MySQL 8.4 Release Notes
本节提供有关 NDB Cluster 软件以及在执行升级和降级操作时不同 NDB Cluster 版本之间兼容性的信息。在尝试升级或降级之前，您应该已经熟悉 NDB Cluster 的安装和配置。请参阅 第 25.4 节，“NDB Cluster 配置”。This section provides information about NDB Cluster software and compatibility between different NDB Cluster releases with regard to performing upgrades and downgrades. You should already be familiar with installing and configuring NDB Cluster prior to attempting an upgrade or downgrade. See Section 25.4, “Configuration of NDB Cluster”.
有关从以前版本升级到 NDB 8.4 的信息，请参阅 支持升级到 NDB 8.4 的版本。For information about upgrades to NDB 8.4 from previous versions, see Versions Supported for Upgrade to NDB 8.4.
有关升级或降级 NDB 8.4 时已知问题和遇到的问题的信息，请参见 升级或降级 NDB 集群时的已知问题。For information about known issues and problems encountered when upgrading or downgrading NDB 8.4, see Known Issues When Upgrading or Downgrading NDB Cluster.
以下 NDB 集群版本支持升级到 NDB 集群 8.4：The following versions of NDB Cluster are supported for upgrades to NDB Cluster 8.4:
NDB 集群 8.0：NDB 8.0.19 及以后版本NDB Cluster 8.0: NDB 8.0.19 and later
NDB 集群 8.1 (8.1.0)NDB Cluster 8.1 (8.1.0)
NDB 集群 8.2 (8.2.0)NDB Cluster 8.2 (8.2.0)
NDB 集群 8.3 (8.3.0)NDB Cluster 8.3 (8.3.0)
本节提供有关升级或降级到或从 NDB 8.4 时已知会发生的问题的信息。In this section, provide information about issues known to occur when upgrading or downgrading to or from NDB 8.4.
我们建议您在进行任何 NDB 集群软件升级或降级时，不要尝试进行任何模式更改。原因如下：We recommend that you not attempt any schema changes during any NDB Cluster software upgrade or downgrade. Some of the reasons for this are listed here:
在数据节点启动的某些阶段，无法对
NDB表执行 DDL 语句。DDL statements onNDBtables are not possible during some phases of data node startup.如果在执行过程中有任何数据节点停止，
NDB表上的 DDL 语句可能会被拒绝；在升级或降级过程中，需要停止每个数据节点二进制文件（以便将其替换为目标版本的二进制文件）。DDL statements onNDBtables may be rejected if any data nodes are stopped during execution; stopping each data node binary (so it can be replaced with a binary from the target version) is required as part of the upgrade or downgrade process.当同一集群中的数据节点运行不同版本的 NDB 集群软件时，不允许对
NDB表执行 DDL 语句。DDL statements onNDBtables are not allowed while there are data nodes in the same cluster running different release versions of the NDB Cluster software.
有关用于执行数据节点在线升级或降级的滚动重启过程的更多信息，请参见第 25.6.5 节，“执行 NDB 集群的滚动重启”。For additional information regarding the rolling restart procedure used to perform an online upgrade or downgrade of the data nodes, see Section 25.6.5, “Performing a Rolling Restart of an NDB Cluster”.