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["butler" <zxszcaijin@xxxxxx>]

I just want to know ,Why need fit 256 characters in utf8 charset??Why not 512 characters in utf8 charset ? 


------------------ Original ------------------
From:  "Sergei Golubchik";<serg@xxxxxxxxxxx>;
Date:  Tue, Apr 18, 2017 03:14 AM
To:  "butler"<zxszcaijin@xxxxxx>; 
Cc:  "maria-discuss"<maria-discuss@xxxxxxxxxxxxxxxxxxx>; 
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@xxxxxxxxxxx