mysql_upgrade - Check and upgrade MySQL tables

Let us understand mysql_upgrade program −

Usage

• Every time MySQL is upgraded, the user should execute mysql_upgrade, that looks for incompatibilities with the upgraded MySQL server.

• It upgrades the system tables in the mysql schema so that the user can take advantage of new privileges or capabilities that could have been added after the upgrade.

• It basically upgrades the Performance Schema and sys schema.

• It also examines user schemas.

• If mysql_upgrade finds that a table has a possible incompatibility, it performs a table check and, if some problems are found, attempts a table repair operation

The mysql_upgrade can be used as shown below −

• Ensure that the server is currently running.

• Invoke mysql_upgrade to upgrade the system tables in the mysql schema.

Check and repair tables in other schemas using the below command −

shell> mysql_upgrade [options]

停止服务器并重新启动，以便使任何系统表更改生效。

如果有多个需要升级的MySQL服务器实例，则可以使用适合连接到每个所需服务器的连接参数来调用mysql_upgrade。让我们以一个例子来说明 -

通过连接到适当的端口，升级本地主机上运行的端口为3306到3308的每个服务器。可以使用以下命令来完成这个操作 -

shell> mysql_upgrade --protocol=tcp -P 3306 [other_options]
shell> mysql_upgrade --protocol=tcp -P 3307 [other_options]
shell> mysql_upgrade --protocol=tcp -P 3308 [other_options]

对于Unix上的本地主机连接，--protocol=tcp选项将强制使用TCP/IP连接，而不是Unix套接字文件。

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