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May 7, 2025
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Update pad attribute where needed (#20314) #20318

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14990b6
Add temp.md
lilin90 May 6, 2025
1708612
Delete temp.md
lilin90 May 6, 2025
df070b2
*: update related descriptions
lilin90 May 6, 2025
ca7b13e
Update punctuation for consistency
lilin90 May 6, 2025
2f18456
Update information-schema-collations.md
lilin90 May 7, 2025
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20 changes: 10 additions & 10 deletions character-set-and-collation.md
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Original file line number Diff line number Diff line change
Expand Up @@ -157,16 +157,16 @@ SHOW COLLATION WHERE Charset = 'utf8mb4';
```

```
+--------------------+---------+------+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------+---------+------+---------+----------+---------+
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | | Yes | 1 |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 |
+--------------------+---------+------+---------+----------+---------+
5 rows in set (0.00 sec)
+--------------------+---------+-----+---------+----------+---------+---------------+
| Collation | Charset | Id | Default | Compiled | Sortlen | Pad_attribute |
+--------------------+---------+-----+---------+----------+---------+---------------+
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | | Yes | 0 | NO PAD |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 | NO PAD |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 | PAD SPACE |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 | PAD SPACE |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 | PAD SPACE |
+--------------------+---------+-----+---------+----------+---------+---------------+
5 rows in set (0.001 sec)
```

TiDB 对 GBK 字符集的支持详情见 [GBK](/character-set-gbk.md)。
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42 changes: 21 additions & 21 deletions information-schema/information-schema-collations.md
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Expand Up @@ -7,8 +7,6 @@ summary: 了解 information_schema 表 `COLLATIONS`。

`COLLATIONS` 表提供了 `CHARACTER_SETS` 表中字符集对应的排序规则列表。目前 TiDB 包含该表仅为兼容 MySQL。

{{< copyable "sql" >}}

```sql
USE information_schema;
DESC collations;
Expand All @@ -20,39 +18,41 @@ DESC collations;
+--------------------+-------------+------+------+---------+-------+
| COLLATION_NAME | varchar(32) | YES | | NULL | |
| CHARACTER_SET_NAME | varchar(32) | YES | | NULL | |
| ID | bigint(11) | YES | | NULL | |
| ID | bigint | YES | | NULL | |
| IS_DEFAULT | varchar(3) | YES | | NULL | |
| IS_COMPILED | varchar(3) | YES | | NULL | |
| SORTLEN | bigint(3) | YES | | NULL | |
| SORTLEN | bigint | YES | | NULL | |
| PAD_ATTRIBUTE | varchar(9) | YES | | NULL | |
+--------------------+-------------+------+------+---------+-------+
6 rows in set (0.00 sec)
7 rows in set (0.001 sec)
```

{{< copyable "sql" >}}

```sql
SELECT * FROM collations WHERE character_set_name='utf8mb4';
```

```sql
+--------------------+--------------------+------+------------+-------------+---------+
| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN |
+--------------------+--------------------+------+------------+-------------+---------+
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 |
+--------------------+--------------------+------+------------+-------------+---------+
3 rows in set (0.001 sec)
+--------------------+--------------------+------+------------+-------------+---------+---------------+
| COLLATION_NAME | CHARACTER_SET_NAME | ID | IS_DEFAULT | IS_COMPILED | SORTLEN | PAD_ATTRIBUTE |
+--------------------+--------------------+------+------------+-------------+---------+---------------+
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | | Yes | 0 | NO PAD |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 | NO PAD |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 | PAD SPACE |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 | PAD SPACE |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 | PAD SPACE |
+--------------------+--------------------+------+------------+-------------+---------+---------------+
5 rows in set (0.001 sec)
```

`COLLATIONS` 表中列的含义如下：

* `COLLATION_NAME`：排序规则名称
* `CHARACTER_SET_NAME`：排序规则所属的字符集名称
* `ID`：排序规则的 ID
* `IS_DEFAULT`：该排序规则是否是所属字符集的默认排序规则
* `IS_COMPILED`：字符集是否编译到服务器中
* `SORTLEN`：排序规则在对字符进行排序时，所分配内存的最小长度
* `COLLATION_NAME`：排序规则名称。
* `CHARACTER_SET_NAME`：排序规则所属的字符集名称。
* `ID`：排序规则的 ID。
* `IS_DEFAULT`：该排序规则是否是所属字符集的默认排序规则。
* `IS_COMPILED`：字符集是否编译到服务器中。
* `SORTLEN`：排序规则在对字符进行排序时，所分配内存的最小长度。
* `PAD_ATTRIBUTE`：在比较字符串时是否忽略末尾空格。`PAD SPACE` 表示忽略末尾空格（例如 `'abc'` 等于 `'abc '`），而 `NO PAD` 表示末尾空格会影响比较结果（例如 `'abc'` 不等于 `'abc '`）。

## 另请参阅

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20 changes: 10 additions & 10 deletions sql-statements/sql-statement-show-collation.md
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Expand Up @@ -78,16 +78,16 @@ SHOW COLLATION WHERE Charset="utf8mb4";
```

```
+--------------------+---------+-----+---------+----------+---------+
| Collation | Charset | Id | Default | Compiled | Sortlen |
+--------------------+---------+-----+---------+----------+---------+
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | | Yes | 1 |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 1 |
+--------------------+---------+-----+---------+----------+---------+
5 rows in set (0.00 sec)
+--------------------+---------+-----+---------+----------+---------+---------------+
| Collation | Charset | Id | Default | Compiled | Sortlen | Pad_attribute |
+--------------------+---------+-----+---------+----------+---------+---------------+
| utf8mb4_0900_ai_ci | utf8mb4 | 255 | | Yes | 0 | NO PAD |
| utf8mb4_0900_bin | utf8mb4 | 309 | | Yes | 1 | NO PAD |
| utf8mb4_bin | utf8mb4 | 46 | Yes | Yes | 1 | PAD SPACE |
| utf8mb4_general_ci | utf8mb4 | 45 | | Yes | 1 | PAD SPACE |
| utf8mb4_unicode_ci | utf8mb4 | 224 | | Yes | 8 | PAD SPACE |
+--------------------+---------+-----+---------+----------+---------+---------------+
5 rows in set (0.001 sec)
```

## MySQL 兼容性
Expand Down