------------------ Original ------------------

From: "Sergei Golubchik";<serg@mariadb.org>;

Date: Tue, Apr 18, 2017 03:14 AM

To: "butler"<zxszcaijin@qq.com>;

Cc: "maria-discuss"<maria-discuss@lists.launchpad.net>;

Subject: Re: [Maria-discuss] innodb table single column index max length

Hi, butler!

On Apr 17, butler wrote:
> we know the mysql have a limit that the max index length on a single
> column is 767.I want know how the 767 come from ? why not 799 or 800
> etc.

768 is 256*3, originally selected to fit 256 characters in utf8 charset,
each character can be up to 3 bytes long.

767 is 768-1.

Regards,
Sergei
Chief Architect MariaDB
and security@mariadb.org