Bug #76529 NCHAR and NVARCHAR should use utf8mb4 as predefined character set by default
Submitted: 30 Mar 2015 12:22 Modified: 20 Apr 2015 22:49
Reporter: Ryusuke Kajiyama Email Updates:
Status: Verified Impact on me:
None 
Category:MySQL Server: Data Types Severity:S4 (Feature request)
Version:5.7, 8.0 OS:Any
Assigned to: CPU Architecture:Any
Tags: Character Data Type, i18n, National Character Set

[30 Mar 2015 12:22] Ryusuke Kajiyama 
Description:
Starting from MySQL 4.1, NCHAR is using utf8 as predefined character set. However, utf8 is subset of utf8mb4, and utf8mb4 is becoming more common in modern applications. 

How to repeat:
http://dev.mysql.com/doc/refman/5.7/en/charset-national.html
"MySQL 5.7 uses utf8 as this predefined character set."

This description is the same since 4.1 ref man.
http://dev.mysql.com/doc/refman/4.1/en/charset-national.html

Suggested fix:
NCHAR and NVARCHAR to use utf8mb4 as predefined character set by default
[20 Apr 2015 22:49] MySQL Verification Team 
Thank you for the bug report.
[15 Jun 2020 3:19] Ryusuke Kajiyama 
MySQL 8.0.20 outputs following Warning message when tables with NATIONAL/NCHAR/NVARCHAR was created;

Warning (code 3720): NATIONAL/NCHAR/NVARCHAR implies the character set UTF8MB3, which will be replaced by UTF8MB4 in a future release. Please consider using CHAR(x) CHARACTER SET UTF8MB4 in order to be unambiguous.