最近在一次MySQL数据迁移的过程中遭遇了字符集的问题，提示为Character set
最近在一次mysql数据迁移的过程中遭遇了字符集的问题，提示为"character set 'utf8mb4' is not a compiled character set"。即是字符集utf8mb4不是一个编译的字符集以及没有在index.xml文件里指定。下面是其处理过程及解决办法，供大家参考。
1、错误提示
SHELL> mysqlbinlog --database=bs_salary --stop-datetime="2014-12-15 8:24:48" /home/robin/mysql-bin.000399 \
> |mysql -uroot -p --force --database=salary_1215
mysql: Character set 'utf8mb4' is not a compiled character set and is not specified in the '/usr/share/mysql/charsets/Index.xml' file
2、分析与解决
a、错误分析
从给出的错误提示来看，说utf8mb4字符集未被编译，而事实上这个字符集根本没有用到。
其次说这个文件里/usr/share/mysql/charsets/Index.xml未指定utf8mb4字符集，需要检查字符集目录设置。
b、字符集检查
首先检查了新旧环境的字符集设置，两边都为UTF8，如下
mysql> show variables like '%char%';
+--------------------------+---------------------------------+
| Variable_name | Value |
+--------------------------+---------------------------------+
| character_set_client | utf8 |
| character_set_connection | utf8 |
| character_set_database | utf8 |
| character_set_filesystem | binary |
| character_set_results | utf8 |
| character_set_server | utf8 |
| character_set_system | utf8 |
| character_sets_dir | /app/soft/mysql/share/charsets/ |
+--------------------------+---------------------------------+
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c、服务器字符集路径设置
对于字符集的路径设置，与错误提示不一致，尝试修改器配置文件
SHELL> tail -3 /etc/my.cnf
[client]
#default-character-set=utf8
character-sets-dir=/app/soft/mysql/share/charsets/
修改配置文件后再次碰到错误提示如下，因此字符集路径不是主要原因
mysql: Character set 'utf8mb4' is not a compiled character set and is not specified in the '/app/soft/mysql/share/charsets/Index.xml' file
SHELL> /app/soft/mysql/share/charsets/Index.xml /app/soft/mysql/share/charsets/Index.xml.bk
d、添加utf8mb4字符集到Index.xml
直接复制utf8的配置，改为utf8mb4后，添加到/app/soft/mysql/share/charsets/Index.xml故障解决。
3、MySQL官方解释
https://dev.mysql.com/doc/refman/5.5/en/charset-configuration.html
If you try to use a character set that is not compiled into your binary, you might run into the following problems:
Your program uses an incorrect path to determine where the character sets are stored (which is typically the share/mysql/charsets or share/charsets directory under the MySQL installation directory). This can be fixed by using the --character-sets-dir option when you run the program in question. For example, to specify a directory to be used by MySQL client programs, list it in the [client] group of your option file. The examples given here show what the setting might look like for Unix or Windows, respectively:
[client] character-sets-dir=/usr/local/mysql/share/mysql/charsets [client] character-sets-dir="C:/Program Files/MySQL/MySQL Server 5.5/share/charsets"The character set is a complex character set that cannot be loaded dynamically. In this case, you must recompile the program with support for the character set.
For Unicode character sets, you can define collations without recompiling by using LDML notation. See Section 10.4.4, “Adding a UCA Collation to a Unicode Character Set”.
