MariaDB是否允许255个字符的唯一索引? [英] Does MariaDB allow 255 character unique indexes?

问题描述

我反复从10.0.29-MariaDB-0ubuntu0.16.04.1 Ubuntu 16.04收到此错误

I'm repeatedly getting this error from 10.0.29-MariaDB-0ubuntu0.16.04.1 Ubuntu 16.04

第81行的错误1071(42000):指定的密钥太长；最大键 长度为767字节

ERROR 1071 (42000) at line 81: Specified key was too long; max key length is 767 bytes

目标行通常如下所示:

name VARCHAR(255) NOT NULL UNIQUE,

将其更改为VARCHAR(63)可使错误消失.这是MariaDB中的错误吗?

Changing it to a VARCHAR(63) makes the error go away. Is this a bug in MariaDB?

推荐答案

要变通解决此错误，请执行以下操作之一

To work around this error, do one of

解决方法:执行以下一项操作

Workaround: do one of

• 升级到5.7.7(或更高版本)以获取3072个字节的限制，而不是767
• 在VARCHAR上将255更改为191(假设您的值不太长)
• ALTER .. CONVERT TO utf8-但这不允许表情符号和一些中文
• 使用前缀"索引(不建议使用)
• 重新配置(适用于5.6.3-5.7.6)(如下)

• Upgrade to 5.7.7 (or later) for 3072 byte limit instead of 767
• Change 255 to 191 on the VARCHAR (assuming your values are not too long)
• ALTER .. CONVERT TO utf8 -- but this disallows Emoji and some Chinese
• Use a "prefix" index (ill-advised)
• Reconfigure (for 5.6.3 - 5.7.6) (below)

重新配置5.6.3或5.5.14:

Reconfiguring 5.6.3 or 5.5.14:

SET GLOBAL innodb_file_format=Barracuda;
SET GLOBAL innodb_file_per_table=1;
SET GLOBAL innodb_large_prefix=1;
logout & login (to get the global values);
ALTER TABLE tbl ROW_FORMAT=DYNAMIC;  (or COMPRESSED)

(版本号基于Oracle的MySQL； MariaDB版本号与此问题不同.)

(The version numbers are based on Oracle's MySQL; the MariaDB version numbers are different for this issue.)

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