Swisscom云中mariadb中的默认服务器字符集是什么？如何更改？

这是一份关于SWISCOM Cloud MariaDB服务的澄清请求。这不是关于通用的

我想知道Swisscom云上MariaDB服务的默认定义是什么

假设它实际上是

latin1

，我想知道是否可以更改此默认值（更改为

utf-8

，或者更准确地说，更改为

utf8mb4

）

---

我提出这个问题的主要原因是，我在创建可以轻松重新导入的备份时遇到了问题，并且在通过

mysqldump提取时，我得到的输出大小大不相同-r backup.sql

与通过

Sequel Pro

导出相比

我不使用工具

Sequel Pro

传统的MariaDB/Galera集群在未设置时使用

latin1

作为默认字符集。此默认设置来自上游开发人员。大多数开发人员和DBA不喜欢这个决定

以下是

CREATE TABLE

语法（请参见

COLLATE

和

字符集

）：

服务器设置（此语句可由每个客户执行，无需管理员权限）：

如果您仍在使用legacy MariaDB，请尽快使用。旧群集将在一天或两天内成为只读群集

我们为您准备了全新的MariaDB服务。它来了 经过许多改进（如MariaDB版本10），我们建议 尽快升级

本分步指南已创建

新群集使用更好的默认设置：

MariaDB [(none)]> show global variables like 'character_set%';
+--------------------------+------------------------------------------------------------------------------------------+
| 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       | /var/vcap/data/packages/mariadb/95a1896c4bcdccb4e1abd81b7d00eb33aedb0da0/share/charsets/ |
+--------------------------+------------------------------------------------------------------------------------------+
8 rows in set (0.01 sec)

如果希望在将数据导入新集群之前更改字符集和排序规则

ALTER TABLE tbl_name
    [[DEFAULT] CHARACTER SET charset_name]
    [COLLATE collation_name]

我们做了很多次。请记住，您不应该在超过20000条记录的情况下执行此操作

请也看看我们的

如有需要，请联系Swisscom应用程序云支持 发布长时间运行的DDL更改（例如

ALTERTABLE

（记录汇编）。长时间运行的DDL会导致上的所有客户停机 集群

---

这是为了演示两种不同的

更改

；一事无成；一个人做你想做的事：

--尝试“错误的”更改：

    DROP TABLE IF EXISTS atc;
    CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
    INSERT INTO atc (c) VALUES ('ÃÔäô');
    SHOW CREATE TABLE atc\G
    SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
    ALTER TABLE atc CHARACTER SET utf8;
    SHOW CREATE TABLE atc\G   -- the column stays latin1, overriding the table
    SELECT c, HEX(c) FROM atc;   -- still latin1 encoding

mysql> 
mysql> -- Try the 'wrong' ALTER:
mysql> 
mysql> DROP TABLE IF EXISTS atc;
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO atc (c) VALUES ('ÃÔäô');
Query OK, 1 row affected (0.00 sec)

mysql> SHOW CREATE TABLE atc\G
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
+----------+----------+
| c        | HEX(c)   |
+----------+----------+
| ÃÔäô     | C3D4E4F4 |
+----------+----------+
1 row in set (0.00 sec)

mysql> ALTER TABLE atc CHARACTER SET utf8;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> SHOW CREATE TABLE atc\G   -- the column stays latin1, overriding the table
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) CHARACTER SET latin1 DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- still latin1 encoding
+----------+----------+
| c        | HEX(c)   |
+----------+----------+
| ÃÔäô     | C3D4E4F4 |
+----------+----------+
1 row in set (0.00 sec)

--尝试“正确”的方法：

    DROP TABLE IF EXISTS atc;
    CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
    INSERT INTO atc (c) VALUES ('ÃÔäô');
    SHOW CREATE TABLE atc\G
    SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
    ALTER TABLE atc CONVERT TO CHARACTER SET utf8;
    SHOW CREATE TABLE atc\G   -- column and table are utf8
    SELECT c, HEX(c) FROM atc;   -- now utf8

mysql> 
mysql> -- Try the 'right' way:
mysql> 
mysql> DROP TABLE IF EXISTS atc;
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO atc (c) VALUES ('ÃÔäô');
Query OK, 1 row affected (0.00 sec)

mysql> SHOW CREATE TABLE atc\G
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
+----------+----------+
| c        | HEX(c)   |
+----------+----------+
| ÃÔäô     | C3D4E4F4 |
+----------+----------+
1 row in set (0.00 sec)

mysql> ALTER TABLE atc CONVERT TO CHARACTER SET utf8;
Query OK, 1 row affected (0.03 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> SHOW CREATE TABLE atc\G   -- column and table are utf8
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- now utf8
+----------+------------------+
| c        | HEX(c)           |
+----------+------------------+
| ÃÔäô     | C383C394C3A4C3B4 |
+----------+------------------+
1 row in set (0.00 sec)

mysql> 

---

很高兴看到新的MariaDB默认为UTF-8-我们已经进行了切换，但在恢复备份时出现了问题，这似乎与混合字符集有关。。。MySQL的

utf8

是

UTF-8

的一个子集。最好一直转到

utf8mb4

。

ALTER

除了更改新添加列的默认值之外，不做任何其他事情！。请参见

ALTER。。。改为转换为…

。是否只更改默认值？或者您也要更改所有的数据编码？

    DROP TABLE IF EXISTS atc;
    CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
    INSERT INTO atc (c) VALUES ('ÃÔäô');
    SHOW CREATE TABLE atc\G
    SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
    ALTER TABLE atc CHARACTER SET utf8;
    SHOW CREATE TABLE atc\G   -- the column stays latin1, overriding the table
    SELECT c, HEX(c) FROM atc;   -- still latin1 encoding

mysql> 
mysql> -- Try the 'wrong' ALTER:
mysql> 
mysql> DROP TABLE IF EXISTS atc;
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
Query OK, 0 rows affected (0.02 sec)

mysql> INSERT INTO atc (c) VALUES ('ÃÔäô');
Query OK, 1 row affected (0.00 sec)

mysql> SHOW CREATE TABLE atc\G
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
+----------+----------+
| c        | HEX(c)   |
+----------+----------+
| ÃÔäô     | C3D4E4F4 |
+----------+----------+
1 row in set (0.00 sec)

mysql> ALTER TABLE atc CHARACTER SET utf8;
Query OK, 0 rows affected (0.00 sec)
Records: 0  Duplicates: 0  Warnings: 0

mysql> SHOW CREATE TABLE atc\G   -- the column stays latin1, overriding the table
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) CHARACTER SET latin1 DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- still latin1 encoding
+----------+----------+
| c        | HEX(c)   |
+----------+----------+
| ÃÔäô     | C3D4E4F4 |
+----------+----------+
1 row in set (0.00 sec)

    DROP TABLE IF EXISTS atc;
    CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
    INSERT INTO atc (c) VALUES ('ÃÔäô');
    SHOW CREATE TABLE atc\G
    SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
    ALTER TABLE atc CONVERT TO CHARACTER SET utf8;
    SHOW CREATE TABLE atc\G   -- column and table are utf8
    SELECT c, HEX(c) FROM atc;   -- now utf8

mysql> 
mysql> -- Try the 'right' way:
mysql> 
mysql> DROP TABLE IF EXISTS atc;
Query OK, 0 rows affected (0.01 sec)

mysql> CREATE TABLE atc ( c VARCHAR(11))  CHARACTER SET latin1 ;
Query OK, 0 rows affected (0.01 sec)

mysql> INSERT INTO atc (c) VALUES ('ÃÔäô');
Query OK, 1 row affected (0.00 sec)

mysql> SHOW CREATE TABLE atc\G
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=latin1
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- note the latin1 encoding
+----------+----------+
| c        | HEX(c)   |
+----------+----------+
| ÃÔäô     | C3D4E4F4 |
+----------+----------+
1 row in set (0.00 sec)

mysql> ALTER TABLE atc CONVERT TO CHARACTER SET utf8;
Query OK, 1 row affected (0.03 sec)
Records: 1  Duplicates: 0  Warnings: 0

mysql> SHOW CREATE TABLE atc\G   -- column and table are utf8
*************************** 1. row ***************************
       Table: atc
Create Table: CREATE TABLE `atc` (
  `c` varchar(11) DEFAULT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8
1 row in set (0.00 sec)

mysql> SELECT c, HEX(c) FROM atc;   -- now utf8
+----------+------------------+
| c        | HEX(c)           |
+----------+------------------+
| ÃÔäô     | C383C394C3A4C3B4 |
+----------+------------------+
1 row in set (0.00 sec)

mysql>