执行以下命令时:
ALTER TABLE `mytable` ADD UNIQUE (
`column1` ,
`column2`
);
我得到了这个错误信息:
#1071 - Specified key was too long; max key length is 767 bytes
columnn1和column2的信息:
column1 varchar(20) utf8_general_ci
column2 varchar(500) utf8_general_ci
我认为varchar(20)只需要21个字节，而varchar(500)只需要501个字节。所以总字节数是522，小于767。为什么我得到了错误消息?
#1071 - Specified key was too long; max key length is 767 bytes
当前回答
Laravel框架解决方案
根据Laravel 5.4。*文档;你必须在app/Providers/AppServiceProvider.php文件的引导方法中设置默认字符串长度，如下所示:
use Illuminate\Support\Facades\Schema;
public function boot()
{
Schema::defaultStringLength(191);
}
Laravel 5.4对这个修复的解释。*文档:
Laravel uses the utf8mb4 character set by default, which includes support for storing "emojis" in the database. If you are running a version of MySQL older than the 5.7.7 release or MariaDB older than the 10.2.2 release, you may need to manually configure the default string length generated by migrations in order for MySQL to create indexes for them. You may configure this by calling the Schema::defaultStringLength method within your AppServiceProvider. Alternatively, you may enable the innodb_large_prefix option for your database. Refer to your database's documentation for instructions on how to properly enable this option.
其他回答
MySQL对字符串中每个字符的字节数假设最坏的情况。对于MySQL 'utf8'编码，每个字符是3个字节，因为该编码不允许字符超过U+FFFF。对于MySQL 'utf8mb4'编码，它是每个字符4字节，因为这是MySQL所谓的实际UTF-8。
因此，假设您使用'utf8'，那么您的第一列将占用索引的60字节，第二列将占用索引的1500字节。
如果您最近修改了innodb_log_file_size，请尝试恢复之前的值。
对于这个问题，我自己的解决方案比降低表的VARCHAR大小更简单，也更安全。
情况:CentOS 7服务器运行Plesk Obsidian 18.0.37和MariaDB 5.5。我试图从运行MariaDB 10.1的服务器导入MySQL转储。
解决方案:从MariaDB 5.5升级到10.6。
这些步骤大致基于以下指南和以下指南:
mysqldump -u admin -p`cat /etc/psa/.psa.shadow` --all-databases --routines --triggers > /root/all-databases.sql systemctl stop mariadb cp -a /var/lib/mysql/ /var/lib/mysql_backup Configure MariaDB repositories according to the official guide Make sure you meet Plesk's minimum version requirements detailed here yum install MariaDB-client MariaDB-server MariaDB-compat MariaDB-shared systemctl start mariadb In my case, the server failed to start here with an error: "Can't start server: Bind on TCP/IP port. Got error: 22: Invalid argument". The fix was to replace bind-address as follows in /etc/my.cnf and re-run the command: [mysqld] # OLD (broken) #bind-address = ::ffff:127.0.0.1 # NEW bind-address = 127.0.0.1 MYSQL_PWD=`cat /etc/psa/.psa.shadow` mysql_upgrade -uadmin plesk sbin packagemng -sdf rm -f /etc/init.d/mysql systemctl daemon-reload
请检查sql_mode是否为like
sql_mode=NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES
如果是，则更改为
sql_mode=NO_ENGINE_SUBSTITUTION
OR
重新启动服务器，修改my.cnf文件(如下所示)
innodb_large_prefix=on
我对这个相同问题的修复是添加一个选项作为第三个参数:charset
queryInterface.createTable(
tableName,
{ /*... columns*/ },
{ charset: 'utf8' }
)
否则sequelize将创建utf8mb4表。
