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Update pad attribute where needed #20823

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6bcb253
Update pad attribute where needed
dveeden Apr 21, 2025
6da6c81
Update information-schema/information-schema-collations.md
dveeden Apr 22, 2025
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22 changes: 11 additions & 11 deletions character-set-and-collation.md
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Original file line number Diff line number Diff line change
Expand Up @@ -77,7 +77,7 @@ SELECT

### Character set and collation naming

A character set can have multiple collations, named in the `<character_set>_<collation_properties>` format. For example, the `utf8mb4` character set has a collation called `utf8mb4_bin`, which is a binary collation for `utf8mb4`. Multiple collation properties can be included in the name, separated by underscores (`_`).
A character set can have multiple collations, named in the `<character_set>_<collation_properties>` format. For example, the `utf8mb4` character set has a collation called `utf8mb4_bin`, which is a binary collation for `utf8mb4`. Multiple collation properties can be included in the name, separated by underscores (`_`).

The following table shows the common collation properties and meanings.

Expand Down Expand Up @@ -159,16 +159,16 @@ SHOW COLLATION WHERE Charset = 'utf8mb4';
```

```sql
+--------------------+---------+------+---------+----------+---------+
| 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)
```

For details about the TiDB support of the GBK character set, see [GBK](/character-set-gbk.md).
Expand Down
30 changes: 15 additions & 15 deletions information-schema/information-schema-collations.md
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Expand Up @@ -7,8 +7,6 @@ summary: Learn the `COLLATIONS` information_schema table.

The `COLLATIONS` table provides a list of collations that correspond to character sets in the `CHARACTER_SETS` table. Currently, this table is included only for compatibility with MySQL.

{{< copyable "sql" >}}

```sql
USE information_schema;
DESC collations;
Expand All @@ -20,29 +18,30 @@ 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)
```

The description of columns in the `COLLATIONS` table is as follows:
Expand All @@ -53,6 +52,7 @@ The description of columns in the `COLLATIONS` table is as follows:
* `IS_DEFAULT`: Whether this collation is the default collation of the character set it belongs to.
* `IS_COMPILED`: Whether the character set is compiled into the server.
* `SORTLEN`: The minimum length of memory allocated when the collation sorts characters.
* `PAD_ATTRIBUTE`: Whether trailing spaces are ignored during string comparison. `PAD SPACE` means that trailing spaces are ignored (for example, `'abc'` equals `'abc '`), while `NO PAD` means that trailing spaces are significant (for example, `'abc'` does not equal `'abc '`).

## See also

Expand Down
20 changes: 10 additions & 10 deletions sql-statements/sql-statement-show-collation.md
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Expand Up @@ -87,16 +87,16 @@ SHOW COLLATION WHERE Charset="utf8mb4";
```

```sql
+--------------------+---------+-----+---------+----------+---------+
| 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 compatibility
Expand Down