From 3efaac25ea2a67f3da944af77eb67176e663005f Mon Sep 17 00:00:00 2001 From: bb7133 Date: Fri, 12 Jun 2020 16:34:35 +0800 Subject: [PATCH 1/2] add column description for several information_schema tables --- .../system-table-information-schema.md | 57 +++++++++---------- 1 file changed, 26 insertions(+), 31 deletions(-) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index b7bc755c328a..fbdb0982d97c 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -55,6 +55,13 @@ SELECT * FROM character_sets; 5 rows in set (0.00 sec) ``` +`CHARACTER_SETS` 表中列的含义如下： + +* `CHARACTER_SET_NAME`：字符集名称 +* `DEFAULT_COLLATE_NAME`：字符集的默认排序规则名称 +* `DESCRIPTION`：字符集的描述信息 +* `MAXLEN`：该字符集存储一个字符所需要的最大字节数 + ## COLLATIONS 表 `COLLATIONS` 表提供了 `CHARACTER_SETS` 表中字符集对应的排序规则列表。TiDB 当前仅支持二进制排序规则，包含该表仅为兼容 MySQL。 @@ -99,6 +106,15 @@ SELECT * FROM collations WHERE character_set_name='utf8mb4'; 26 rows in set (0.00 sec) ``` +`COLLATION` 表中列的含义如下： + +* `COLLATION_NAME`：排序规则名称 +* `COLLATION_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_CHARACTER_SET_APPLICABILITY 表 `COLLATION_CHARACTER_SET_APPLICABILITY` 表将排序规则映射至适用的字符集名称。和 `COLLATIONS` 表一样，包含此表也是为了兼容 MySQL。 @@ -110,39 +126,18 @@ SELECT * FROM collation_character_set_applicability WHERE character_set_name='ut ``` ```sql -+------------------------+--------------------+ -| COLLATION_NAME | CHARACTER_SET_NAME | -+------------------------+--------------------+ -| utf8mb4_general_ci | utf8mb4 | -| utf8mb4_bin | utf8mb4 | -| utf8mb4_unicode_ci | utf8mb4 | -| utf8mb4_icelandic_ci | utf8mb4 | -| utf8mb4_latvian_ci | utf8mb4 | -| utf8mb4_romanian_ci | utf8mb4 | -| utf8mb4_slovenian_ci | utf8mb4 | -| utf8mb4_polish_ci | utf8mb4 | -| utf8mb4_estonian_ci | utf8mb4 | -| utf8mb4_spanish_ci | utf8mb4 | -| utf8mb4_swedish_ci | utf8mb4 | -| utf8mb4_turkish_ci | utf8mb4 | -| utf8mb4_czech_ci | utf8mb4 | -| utf8mb4_danish_ci | utf8mb4 | -| utf8mb4_lithuanian_ci | utf8mb4 | -| utf8mb4_slovak_ci | utf8mb4 | -| utf8mb4_spanish2_ci | utf8mb4 | -| utf8mb4_roman_ci | utf8mb4 | -| utf8mb4_persian_ci | utf8mb4 | -| utf8mb4_esperanto_ci | utf8mb4 | -| utf8mb4_hungarian_ci | utf8mb4 | -| utf8mb4_sinhala_ci | utf8mb4 | -| utf8mb4_german2_ci | utf8mb4 | -| utf8mb4_croatian_ci | utf8mb4 | -| utf8mb4_unicode_520_ci | utf8mb4 | -| utf8mb4_vietnamese_ci | utf8mb4 | -+------------------------+--------------------+ -26 rows in set (0.00 sec) ++----------------+--------------------+ +| COLLATION_NAME | CHARACTER_SET_NAME | ++----------------+--------------------+ +| utf8mb4_bin | utf8mb4 | ++----------------+--------------------+ ``` +`COLLATION_CHARACTER_SET_APPLICABILITY` 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 + ## COLUMNS 表 `COLUMNS` 表提供了表的所有列的信息。 From 2a836745fbe943b5838bca007251cd1d0df2978c Mon Sep 17 00:00:00 2001 From: bb7133 Date: Tue, 16 Jun 2020 14:35:58 +0800 Subject: [PATCH 2/2] address comment --- system-tables/system-table-information-schema.md | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/system-tables/system-table-information-schema.md b/system-tables/system-table-information-schema.md index fbdb0982d97c..ec55156e2e53 100644 --- a/system-tables/system-table-information-schema.md +++ b/system-tables/system-table-information-schema.md @@ -109,7 +109,7 @@ SELECT * FROM collations WHERE character_set_name='utf8mb4'; `COLLATION` 表中列的含义如下： * `COLLATION_NAME`：排序规则名称 -* `COLLATION_NAME`：排序规则所属的字符集名称 +* `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