mysqldump with utf8 can not export the right emojis string

Question

I am using MySQL 5.5.29, utf8mb4 charset, there is a table user containing a field nickname with value hex F09F988EF09F988E that translates to the emojis 😎😎.

Now open MySQL console, and execute:

---

set names utf8mb4;
select nickname, hex(nickname) from user;

---

nickname | hex(nickname)
---------+-----------------
😎😎    | F09F988EF09F988E

---

And then execute:

mysqldump --default-character-set=utf8 -utest -ptest test_dev user > user.sql

Check the user.sql and find the nickname display ?? which hex string is 3f

So, how can mysqldump with UTF8 export the right emojis string?

---

btw, the database charset envionments configured as follow: show variables like 'character_set_%':

'character_set_client', 'utf8mb4'
'character_set_connection', 'utf8mb4'
'character_set_database', 'utf8mb4'
'character_set_filesystem', 'binary'
'character_set_results', 'utf8mb4'
'character_set_server', 'utf8mb4'
'character_set_system', 'utf8'
'character_sets_dir', '/data/mysql/share/charsets/'

Answer 1

Thanks Danack!
Thru specifying utf8mb4 charset and upgrading mysqldump version to 5.5.3+, mysqldump & mysql work well for 4 bytes emojis.

[tomcat@localhost ~]$ mysqldump --default-character-set=utf8mb4 -utest -ptest test_dev user > user.sql

If it shows an error like:

mysqldump: Character set 'utf8mb4' is not a compiled character set and is not specified in the '/usr/share/mysql/charsets/Index.xml' file

check your mysqldump version (mysqldump --version)

[tomcat@localhost ~]$ mysqldump --version
mysqldump  Ver 10.11 Distrib 5.0.95, for redhat-linux-gnu (x86_64)

It works after upgrading mysqldump to 5.5.33.

[tomcat@localhost ~]$ mysqldump --version
mysqldump  Ver 10.13 Distrib 5.5.33, for Linux (x86_64)