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
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
其他回答
对我来说，#1071 -指定键太长了;通过限制列大小200来改变主键/唯一键组合后，最大键长度是767字节”得到了解决。
ALTER TABLE `mytable` ADD UNIQUE (
`column1` (200) ,
`column2` (200)
);
将抱怨索引字段的CHARSET更改为“latin1” 例如:ALTER TABLE tbl CHANGE myfield varchar(600) CHARACTER SET latin1 DEFAULT NULL Latin1为一个字符使用一个字节，而不是四个
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
只是在创建表时将utf8mb4更改为utf8就解决了我的问题。例如:CREATE TABLE…DEFAULT CHARSET=utf8mb4 COLLATE=utf8mb4_unicode_ci;创建表…DEFAULT CHARSET=utf8 COLLATE=utf8_unicode_ci;
如果你要创建如下内容:
CREATE TABLE IF NOT EXISTS your_table (
id int(7) UNSIGNED NOT NULL AUTO_INCREMENT,
name varchar(256) COLLATE utf8mb4_bin NOT NULL,
PRIMARY KEY (id),
UNIQUE KEY name (name)
) ENGINE=INNODB DEFAULT CHARSET=utf8mb4 AUTO_INCREMENT=1 ROW_FORMAT=FIXED;
应该是这样的
CREATE TABLE IF NOT EXISTS your_table (
id int(7) UNSIGNED NOT NULL AUTO_INCREMENT,
name varchar(256) COLLATE utf8mb4_bin NOT NULL,
PRIMARY KEY (id)
) ENGINE=INNODB DEFAULT CHARSET=utf8mb4 AUTO_INCREMENT=1 ROW_FORMAT=FIXED;
但是您需要从代码中检查该列的唯一性，或者添加一个新列作为varchar列的MD5或SHA1
