Fix some issues in information schema docs

information-schema/information-schema-analyze-status.md

@@ -29,8 +29,6 @@ DESC analyze_status;
 7 rows in set (0.00 sec)
 ```
 
-The `STATE` column shows the execution status of a specific `ANALYZE` task. Its value can be `pending`, `running`,`finished` or `failed`.
-
 {{< copyable "sql" >}}
 
 ```sql
@@ -49,4 +47,14 @@ SELECT * FROM `ANALYZE_STATUS`;
 | test         | t1         | p2             | analyze columns   | 1              | 2019-06-21 19:51:15 | finished |
 +--------------+------------+----------------+-------------------+----------------+---------------------+----------+
 6 rows in set
-```
+```
+
+Fields in the `ANALYZE_STATUS` table are described as follows:
+
+* `TABLE_SCHEMA`: The name of the database to which the table belongs.
+* `TABLE_NAME`: The name of the table.
+* `PARTITION_NAME`: The name of the partitioned table.
+* `JOB_INFO`: The information of the `ANALYZE` task.
+* `PROCESSED_ROWS`: The number of rows that have been processed.
+* `START_TIME`: The start time of the `ANALYZE` task.
+* `STATE`: The execution status of the `ANALYZE` task. Its value can be `pending`, `running`,`finished` or `failed`.

information-schema/information-schema-collation-character-set-applicability.md

@@ -30,7 +30,7 @@ DESC collation_character_set_applicability;
 SELECT * FROM collation_character_set_applicability WHERE character_set_name='utf8mb4';
 ```
 
-```
+```sql
 +----------------+--------------------+
 | COLLATION_NAME | CHARACTER_SET_NAME |
 +----------------+--------------------+
@@ -39,11 +39,6 @@ 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.

information-schema/information-schema-collations.md

@@ -34,7 +34,7 @@ DESC collations;
 SELECT * FROM collations WHERE character_set_name='utf8mb4';
 ```
 
-```
+```sql
 +----------------+--------------------+------+------------+-------------+---------+
 | COLLATION_NAME | CHARACTER_SET_NAME | ID   | IS_DEFAULT | IS_COMPILED | SORTLEN |
 +----------------+--------------------+------+------------+-------------+---------+
@@ -43,16 +43,11 @@ 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:
+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.
+* `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.
+* `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.

information-schema/information-schema-processlist.md

@@ -9,7 +9,7 @@ summary: Learn the `PROCESSLIST` information_schema table.
 
 The `PROCESSLIST` table has additional columns not present in `SHOW PROCESSLIST`:
 
-* A `MEM` column to show memory occupied by the request being handled (in bytes)
+* A `MEM` column to show the memory used by the request that is being processed, in bytes.
 * A `TxnStart` column to show the start time of the transaction
 
 {{< copyable "sql" >}}
@@ -69,6 +69,7 @@ Fields in the `PROCESSLIST` table are described as follows:
 * STATE: The current connection state.
 * INFO: The requested statement that is being processed.
 * MEM: The memory used by the request that is being processed, in bytes.
+* TxnStart: The start time of the transaction.
 
 ## CLUSTER_PROCESSLIST
 

information-schema/information-schema-session-variables.md

@@ -14,7 +14,7 @@ USE information_schema;
 DESC session_variables;
 ```
 
-```
+```sql
 +----------------+---------------+------+------+---------+-------+
 | Field          | Type          | Null | Key  | Default | Extra |
 +----------------+---------------+------+------+---------+-------+
@@ -30,7 +30,7 @@ DESC session_variables;
 SELECT * FROM session_variables ORDER BY variable_name LIMIT 10;
 ```
 
-```
+```sql
 +-----------------------------------+------------------+
 | VARIABLE_NAME                     | VARIABLE_VALUE   |
 +-----------------------------------+------------------+
@@ -51,5 +51,4 @@ SELECT * FROM session_variables ORDER BY variable_name LIMIT 10;
 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.
+* `VARIABLE_VALUE`: The value of the session-level variable in the database.

information-schema/information-schema-statistics.md

@@ -14,7 +14,7 @@ USE information_schema;
 DESC statistics;
 ```
 
-```
+```sql
 +---------------+---------------+------+------+---------+-------+
 | Field         | Type          | Null | Key  | Default | Extra |
 +---------------+---------------+------+------+---------+-------+
@@ -40,6 +40,27 @@ DESC statistics;
 18 rows in set (0.00 sec)
 ```
 
+Fields in the `STATISTICS` table are described as follows:
+
+* `TABLE_CATALOG`: The name of the catalog to which the table containing the index belongs. This value is always `def`.
+* `TABLE_SCHEMA`: The name of the database to which the table containing the index belongs.
+* `TABLE_NAME`: The name of the table containing the index.
+* `NON_UNIQUE`: If the index must not contain duplicate values, the value is `0`; if duplicate values are allowed in the index, the value is `1`.
+* `INDEX_SCHEMA`: The name of the database to which the index belongs.
+* `INDEX_NAME`: The name of the index. If the index is the primary key, then the value is always `PRIMARY`.
+* `SEQ_IN_INDEX`: The column number in the index, starting from `1`.
+* `COLUMN_NAME`: The column name. See the description of the `Expression` column.
+* `COLLATION`: The sorting method of the columns in the index. The value can be `A` (ascending order), `D` (descending order) or `NULL` (unsorted).
+* `CARDINALITY`: The estimated number of unique values ​​in the index. To update this value, execute `ANALYZE TABLE`.
+* `SUB_PART`: The prefix of the index. If only part of the prefix of the column is indexed, the value is the number of indexed characters; if the entire column is indexed, the value is `NULL`.
+* `PACKED`: TiDB does not use this field. This value is always `NULL`.
+* `NULLABLE`: If the column might contain a `NULL` value, the value is `YES`; if not, the value is `''`.
+* `INDEX_TYPE`: The type of the index.
+* `COMMENT`: Other information related to the index.
+* `INDEX_COMMENT`: Any comment with comment attribute provided for the index when creating the index.
+* `IS_VISIBLE`: Whether the optimizer can use this index.
+* `Expression` For the index key of the non-expression part, this value is `NULL`; for the index key of the expression part, this value is the expression itself. Refer to [Expression Index](/sql-statements/sql-statement-create-index.md#expression-index).
+
 The following statements are equivalent:
 
 ```sql

information-schema/information-schema-table-constraints.md

@@ -14,7 +14,7 @@ USE information_schema;
 DESC table_constraints;
 ```
 
-```
+```sql
 +--------------------+--------------+------+------+---------+-------+
 | Field              | Type         | Null | Key  | Default | Extra |
 +--------------------+--------------+------+------+---------+-------+
@@ -34,7 +34,7 @@ DESC table_constraints;
 SELECT * FROM table_constraints WHERE constraint_type='UNIQUE';
 ```
 
-```
+```sql
 +--------------------+--------------------+-------------------------+--------------------+-------------------------------------+-----------------+
 | CONSTRAINT_CATALOG | CONSTRAINT_SCHEMA  | CONSTRAINT_NAME         | TABLE_SCHEMA       | TABLE_NAME                          | CONSTRAINT_TYPE |
 +--------------------+--------------------+-------------------------+--------------------+-------------------------------------+-----------------+
@@ -49,5 +49,10 @@ SELECT * FROM table_constraints WHERE constraint_type='UNIQUE';
 7 rows in set (0.01 sec)
 ```
 
-- The `CONSTRAINT_TYPE` value can be `UNIQUE`, `PRIMARY KEY`, or `FOREIGN KEY`.
-- The `UNIQUE` and `PRIMARY KEY` information is similar to the result of the `SHOW INDEX` statement.
+Fields in the `TABLE_CONSTRAINTS` table are described as follows:
+
+* `CONSTRAINT_CATALOG`: The name of the catalog to which the constraint belongs. This value is always `def`.
+* `CONSTRAINT_SCHEMA`: The name of the database to which the constraint belongs.
+* `CONSTRAINT_NAME`: The name of the constraint.
+* `TABLE_NAME`: The name of the table.
+* `CONSTRAINT_TYPE`: The type of the constraint. The value can be `UNIQUE`, `PRIMARY KEY` or `FOREIGN KEY`. The `UNIQUE` and `PRIMARY KEY` information is similar to the execution result of the `SHOW INDEX` statement.

information-schema/information-schema-tables.md

@@ -14,7 +14,7 @@ USE information_schema;
 DESC tables;
 ```
 
-```
+```sql
 +---------------------------+---------------+------+------+----------+-------+
 | Field                     | Type          | Null | Key  | Default  | Extra |
 +---------------------------+---------------+------+------+----------+-------+
@@ -51,7 +51,7 @@ DESC tables;
 SELECT * FROM tables WHERE table_schema='mysql' AND table_name='user'\G
 ```
 
-```
+```sql
 *************************** 1. row ***************************
             TABLE_CATALOG: def
              TABLE_SCHEMA: mysql

information-schema/information-schema-tikv-region-peers.md

@@ -44,9 +44,9 @@ WHERE
   region.region_id = peer.region_id
  AND peer.is_leader = 1
  AND peer.store_id = tikv.store_id;
- ```
+```
 
- Fields in the `TIKV_REGION_PEERS` table are described as follows:
+Fields in the `TIKV_REGION_PEERS` table are described as follows:
 
 * REGION_ID: The Region ID.
 * PEER_ID: The ID of the Region peer.

information-schema/information-schema.md

@@ -67,7 +67,7 @@ Many `INFORMATION_SCHEMA` tables have a corresponding `SHOW` command. The benefi
 | [`INSPECTION_RULES`](/information-schema/information-schema-inspection-rules.md)        | A list of internal diagnostic checks performed. |
 | [`INSPECTION_SUMMARY`](/information-schema/information-schema-inspection-summary.md)    | A summarized report of important monitoring metrics. |
 | [`METRICS_SUMMARY`](/information-schema/information-schema-metrics-summary.md)          | A summary of metrics extracted from Prometheus. |
-| `METRICS_SUMMARY_BY_LABEL`                                                              | See `METRICS_SUMAMARY` table. |
+| `METRICS_SUMMARY_BY_LABEL`                                                              | See `METRICS_SUMMARY` table. |
 | [`METRICS_TABLES`](/information-schema/information-schema-metrics-tables.md)            | Provides the PromQL definitions for tables in `METRICS_SCHEMA`. |
 | [`SEQUENCES`](/information-schema/information-schema-sequences.md)                      | The TiDB implementation of sequences is based on MariaDB. |
 | [`SLOW_QUERY`](/information-schema/information-schema-slow-query.md)                    | Provides information on slow queries on the current TiDB server. |