diff --git a/information-schema/information-schema-character-sets.md b/information-schema/information-schema-character-sets.md index 3c7939cf5ddf8..c579e9c27fe05 100644 --- a/information-schema/information-schema-character-sets.md +++ b/information-schema/information-schema-character-sets.md @@ -43,4 +43,11 @@ SELECT * FROM `character_sets`; | binary | binary | binary | 1 | +--------------------+----------------------+---------------+--------+ 5 rows in set (0.00 sec) -``` \ No newline at end of file +``` + +The description of columns in the `CHARACTER_SETS` table is as follows: + +* `CHARACTER_SET_NAME`: The name of the character set. +* `DEFAULT_COLLATE_NAME` The default collation name of the character set. +* `DESCRIPTION` The description of the character set. +* `MAXLEN` The maximum length required to store a character in this character set. diff --git a/information-schema/information-schema-collation-character-set-applicability.md b/information-schema/information-schema-collation-character-set-applicability.md index 67ee8ac0ae684..1bc8238b9f1e0 100644 --- a/information-schema/information-schema-collation-character-set-applicability.md +++ b/information-schema/information-schema-collation-character-set-applicability.md @@ -38,3 +38,13 @@ SELECT * FROM collation_character_set_applicability WHERE character_set_name='ut +----------------+--------------------+ 1 row in set (0.00 sec) ``` + ++----------------+--------------------+ +| COLLATION_NAME | CHARACTER_SET_NAME | +| utf8mb4_bin | utf8mb4 | ++----------------+--------------------+ + +The description of columns in the `COLLATION_CHARACTER_SET_APPLICABILITY` table is as follows: + +* `COLLATION_NAME`: The name of the collation. +* `CHARACTER_SET_NAME`: The name of the character set which the collation belongs to. diff --git a/information-schema/information-schema-collations.md b/information-schema/information-schema-collations.md index 5196b77c49090..1b3dec5ecc476 100644 --- a/information-schema/information-schema-collations.md +++ b/information-schema/information-schema-collations.md @@ -42,3 +42,17 @@ SELECT * FROM collations WHERE character_set_name='utf8mb4'; +----------------+--------------------+------+------------+-------------+---------+ 1 row in set (0.00 sec) ``` + +The description of columns in the `COLLATION` table is +as follows: + +* `COLLATION_NAME`: The name of the collation. +* `CHARACTER_SET_NAME`: The name of the character set +which the collation belongs to. +* `ID`: The ID of the collation. +* `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. diff --git a/information-schema/information-schema-session-variables.md b/information-schema/information-schema-session-variables.md index bc8a786696b20..04460c8838e7c 100644 --- a/information-schema/information-schema-session-variables.md +++ b/information-schema/information-schema-session-variables.md @@ -46,4 +46,10 @@ SELECT * FROM session_variables ORDER BY variable_name LIMIT 10; | bind_address | * | +-----------------------------------+------------------+ 10 rows in set (0.00 sec) -``` \ No newline at end of file +``` + +The description of columns in the `SESSION_VARIABLES` table is as follows: + +* `VARIABLE_NAME`: The name of the session-level variable in the database. +* `VARIABLE_VALUE`: The value of the session-level +variable in the database. diff --git a/information-schema/information-schema-tables.md b/information-schema/information-schema-tables.md index 28dca095253fe..616be7fde1115 100644 --- a/information-schema/information-schema-tables.md +++ b/information-schema/information-schema-tables.md @@ -91,6 +91,30 @@ SHOW TABLES [LIKE 'wild'] ``` +The description of columns in the `TABLES` table is as follows: + +* `TABLE_CATALOG`: The name of the catalog which the table belongs to. The value is always `def`. +* `TABLE_SCHEMA`: The name of the schema which the table belongs to. +* `TABLE_NAME`: The name of the table. +* `TABLE_TYPE`: The type of the table. +* `ENGINE`: The type of the storage engine. The value is currently `InnoDB`. +* `VERSION`: Version. The value is `10` by default. +* `ROW_FORMAT`: The row format. The value is currently `Compact`. +* `TABLE_ROWS`: The number of rows in the table in statistics. +* `AVG_ROW_LENGTH`: The average row length of the table. `AVG_ROW_LENGTH` = `DATA_LENGTH` / `TABLE_ROWS`. +* `DATA_LENGTH`: Data length. `DATA_LENGTH` = `TABLE_ROWS` \* the sum of storage lengths of the columns in the tuple. The replicas of TiKV are not taken into account. +* `MAX_DATA_LENGTH`: The maximum data length. The value is currently `0`, which means the data length has no upper limit. +* `INDEX_LENGTH`: The index length. `INDEX_LENGTH` = `TABLE_ROWS` \* the sum of lengths of the columns in the index tuple. The replicas of TiKV are not taken into account. +* `DATA_FREE`: Data fragment. The value is currently `0`. +* `AUTO_INCREMENT`: The current step of the auto- increment primary key. +* `CREATE_TIME`: The time at which the table is created. +* `UPDATE_TIME`: The time at which the table is updated. +* `CHECK_TIME`: The time at which the table is checked. +* `TABLE_COLLATION`: The collation of strings in the table. +* `CHECKSUM`: Checksum. +* `CREATE_OPTIONS`: Creates options. +* `TABLE_COMMENT`: The comments and notes of the table. + Most of the information in the table is the same as MySQL. Only two columns are newly defined by TiDB: * `TIDB_TABLE_ID`: to indicate the internal ID of a table. This ID is unique in a TiDB cluster. diff --git a/information-schema/information-schema-tidb-hot-regions.md b/information-schema/information-schema-tidb-hot-regions.md index 98ead5d7daa1b..7ced317f88518 100644 --- a/information-schema/information-schema-tidb-hot-regions.md +++ b/information-schema/information-schema-tidb-hot-regions.md @@ -32,5 +32,15 @@ DESC tidb_hot_regions; 10 rows in set (0.00 sec) ``` -- `TABLE_ID` and `INDEX_ID` are IDs generated for the corresponding table and index in TiDB. -- `TYPE` is the type for a hot Region. Its value can be `READ` or `WRITE`. \ No newline at end of file +The description of columns in the `TIDB_HOT_REGIONS` table is as follows: + +* `TABLE_ID`: ID of located. +* `INDEX_ID`: ID of the table in which the hot Region is the index in which the hot Region is located. +* `DB_NAME`: The database name of the object in which the hot Region is located. +* `TABLE_NAME`: The name of the table in which the hot Region is located. +* `INDEX_NAME`: The name of the index in which the hot Region is located. +* `REGION_ID`: ID of the hot Region. +* `TYPE`: The type of the hot Region. +* `MAX_HOT_DEGREE`: The maximum hot degree of the Region. +* `REGION_COUNT`: The number of Regions in the instance. +* `FLOW_BYTES`: The number of bytes written and read in the Region.