请查看 第 3.1 节，“开始之前” 中的信息。Review the information in Section 3.1, “Before You Begin”.

通过完成 第 3.6 节，“为升级准备安装” 中的初步检查，确保您的安装升级准备就绪。Ensure the upgrade readiness of your installation by completing the preliminary checks in Section 3.6, “Preparing Your Installation for Upgrade”.

如果您在使用 InnoDB 的同时使用 XA 事务，请在升级前运行 XA RECOVER 以检查未提交的 XA 事务。如果有返回结果，请通过发出 XA COMMIT 或 XA ROLLBACK 语句来提交或回滚 XA 事务。If you use XA transactions with InnoDB, run XA RECOVER before upgrading to check for uncommitted XA transactions. If results are returned, either commit or rollback the XA transactions by issuing an XA COMMIT or XA ROLLBACK statement.

如果您通常运行的 MySQL 服务器配置了 innodb_fast_shutdown 设置为 2（冷关闭），请通过执行以下任一语句将其配置为执行快速或慢速关闭：If you normally run your MySQL server configured with innodb_fast_shutdown set to 2 (cold shutdown), configure it to perform a fast or slow shutdown by executing either of these statements:

SET GLOBAL innodb_fast_shutdown = 1; -- fast shutdown
SET GLOBAL innodb_fast_shutdown = 0; -- slow shutdown

使用快速或慢速关闭时，InnoDB 会将其撤销日志和数据文件保留在一种可处理的状态，以应对不同版本之间的文件格式差异。With a fast or slow shutdown, InnoDB leaves its undo logs and data files in a state that can be dealt with in case of file format differences between releases.

关闭旧的 MySQL 服务器。例如：Shut down the old MySQL server. For example:

mysqladmin -u root -p shutdown

升级 MySQL 二进制文件或软件包。如果是升级二进制安装，请解压新的 MySQL 二进制分发包。请参阅 获取并解压分发包。对于基于软件包的安装，请安装新的软件包。Upgrade the MySQL binaries or packages. If upgrading a binary installation, unpack the new MySQL binary distribution package. See Obtain and Unpack the Distribution. For package-based installations, install the new packages.

使用现有的数据目录启动 MySQL 8.4 服务器。例如：Start the MySQL 8.4 server, using the existing data directory. For example:

mysqld_safe --user=mysql --datadir=/path/to/existing-datadir &

如果存在加密的 InnoDB 表空间，请使用 --early-plugin-load 选项来加载密钥环插件。If there are encrypted InnoDB tablespaces, use the --early-plugin-load option to load the keyring plugin.

当您启动 MySQL 8.4 服务器时，它会自动检测数据字典表是否存在。如果不存在，服务器会在数据目录中创建这些表，用元数据填充它们，然后继续其正常启动序列。在此过程中，服务器会升级所有数据库对象的元数据，包括数据库、表空间、系统和用户表、视图以及存储程序（存储过程和函数、触发器以及事件调度器事件）。服务器还会删除以前用于存储元数据的文件。例如，在从 MySQL 8.3 升级到 MySQL 8.4 之后，您可能会注意到表不再有 .frm 文件。When you start the MySQL 8.4 server, it automatically detects whether data dictionary tables are present. If not, the server creates them in the data directory, populates them with metadata, and then proceeds with its normal startup sequence. During this process, the server upgrades metadata for all database objects, including databases, tablespaces, system and user tables, views, and stored programs (stored procedures and functions, triggers, and Event Scheduler events). The server also removes files that previously were used for metadata storage. For example, after upgrading from MySQL 8.3 to MySQL 8.4, you may notice that tables no longer have .frm files.

如果此步骤失败，服务器会将数据目录的所有更改恢复。在这种情况下，你应该删除所有重做日志文件，在相同的数据目录上启动你的 MySQL 8.3 服务器，并修复任何错误的原因。然后对 8.3 服务器执行另一次慢关闭，并启动 MySQL 8.4 服务器再次尝试。If this step fails, the server reverts all changes to the data directory. In this case, you should remove all redo log files, start your MySQL 8.3 server on the same data directory, and fix the cause of any errors. Then perform another slow shutdown of the 8.3 server and start the MySQL 8.4 server to try again.

在上一步中，服务器根据需要升级数据字典，对 mysql 系统数据库在 MySQL 8.3 和 MySQL 8.4 之间进行必要的更改，这样您就可以利用新的权限或功能。它还会将 Performance Schema、INFORMATION_SCHEMA 和 sys 数据库更新到 MySQL 8.4，并检查所有用户数据库是否与当前版本的 MySQL 不兼容。In the previous step, the server upgrades the data dictionary as necessary, making any changes required in the mysql system database between MySQL 8.3 and MySQL 8.4, so that you can take advantage of new privileges or capabilities. It also brings the Performance Schema, INFORMATION_SCHEMA, and sys databases up to date for MySQL 8.4, and examines all user databases for incompatibilities with the current version of MySQL.

请查看 第 3.1 节，“开始之前” 中的信息。Review the information in Section 3.1, “Before You Begin”.

从先前的 MySQL 安装中导出现有数据：Export your existing data from the previous MySQL installation:

mysqldump -u root -p
  --add-drop-table --routines --events
  --all-databases --force > data-for-upgrade.sql

关闭旧的 MySQL 服务器。例如：Shut down the old MySQL server. For example:

mysqladmin -u root -p shutdown

安装 MySQL 8.4。有关安装说明，请参见 第 2 章，安装 MySQL。Install MySQL 8.4. For installation instructions, see Chapter 2, Installing MySQL.

初始化一个新的数据目录，如第 2.9.1 节，“初始化数据目录”所述。例如：Initialize a new data directory, as described in Section 2.9.1, “Initializing the Data Directory”. For example:

mysqld --initialize --datadir=/path/to/8.4-datadir
     

复制显示在屏幕上或写入错误日志的临时 'root'@'localhost' 密码以备后用。Copy the temporary 'root'@'localhost' password displayed to your screen or written to your error log for later use.

使用新的数据目录启动 MySQL 8.4 服务器。例如：Start the MySQL 8.4 server, using the new data directory. For example:

mysqld_safe --user=mysql --datadir=/path/to/8.4-datadir &

重置 root 密码：Reset the root password:

$> mysql -u root -p
Enter password: ****  <- enter temporary root password

mysql> ALTER USER USER() IDENTIFIED BY 'your new password';
     

将先前创建的转储文件加载到新的 MySQL 服务器中。例如：Load the previously created dump file into the new MySQL server. For example:

mysql -u root -p --force < data-for-upgrade.sql

执行任何剩余的升级操作：Perform any remaining upgrade operations:

关闭服务器，然后使用 --upgrade=FORCE 选项重新启动服务器，以执行剩余的升级任务：Shut down the server, then restart it with the --upgrade=FORCE option to perform the remaining upgrade tasks:

mysqladmin -u root -p shutdown
mysqld_safe --user=mysql --datadir=/path/to/8.4-datadir --upgrade=FORCE &

使用 --upgrade=FORCE 重启后，服务器会对 MySQL 8.3 和 MySQL 8.4 之间 mysql 系统架构所需进行的任何更改，以便您可以利用新的权限或功能。它还会将 Performance Schema、INFORMATION_SCHEMA 和 sys 架构更新到 MySQL 8.4，并检查所有用户架构是否与当前版本的 MySQL 存在不兼容之处。Upon restart with --upgrade=FORCE, the server makes any changes required in the mysql system schema between MySQL 8.3 and MySQL 8.4, so that you can take advantage of new privileges or capabilities. It also brings the Performance Schema, INFORMATION_SCHEMA, and sys schema up to date for MySQL 8.4, and examines all user schemas for incompatibilities with the current version of MySQL.

升级 MGM 节点。Upgrade MGM nodes.

逐个升级数据节点。Upgrade data nodes one at a time.

逐个升级 API 节点（包括 MySQL 服务器）。Upgrade API nodes one at a time (including MySQL servers).

导入数据字典。Import the data dictionary.

使用 --upgrade=MINIMAL 选项启动新的服务器，以升级数据字典但不升级系统表。Start the new server with the --upgrade=MINIMAL option to upgrade the data dictionary but not the system tables.

MySQL 服务器必须连接到 NDB 才能完成此阶段。如果存在任何 NDB 或 NDBINFO 表，并且服务器无法连接到集群，则会以错误信息退出：The MySQL server must be connected to NDB for this phase to complete. If any NDB or NDBINFO tables exist, and the server cannot connect to the cluster, it exits with an error message:

Failed to Populate DD tables.

通过重新启动每个单独的 mysqld 来升级系统表，且不使用 --upgrade=MINIMAL 选项。Upgrade the system tables by restarting each individual mysqld without the --upgrade=MINIMAL option.