sql: fix two oncall issues (#15195) (#15259)

pingcap · Nov 3, 2023 · 26ddf3f · 26ddf3f
1 parent f06d0f7
commit 26ddf3f
Show file tree

Hide file tree

Showing 2 changed files with 31 additions and 1 deletion.
diff --git a/mysql-schema.md b/mysql-schema.md
@@ -59,12 +59,17 @@ Currently, the `help_topic` is NULL.
 * `tidb_ttl_task`: the current ongoing TTL subtasks
 * `tidb_ttl_job_history`: the execution history of TTL tasks in the last 90 days
 
-## Runaway queries related system tables
+## System tables related to runaway queries
 
 * `tidb_runaway_queries`: the history records of all identified runaway queries in the past 7 days
 * `tidb_runaway_watch`: the watch list of runaway queries
 * `tidb_runaway_watch_done`: a watch list of deleted or expired runaway queries
 
+## System tables related to metadata locks
+
+* `tidb_mdl_view`：a view of metadata locks. You can use it to view information about the currently blocked DDL statements
+* `tidb_mdl_info`：used internally by TiDB to synchronize metadata locks across nodes
+
 ## Miscellaneous system tables
 
 - `GLOBAL_VARIABLES`: global system variable table

diff --git a/sql-statements/sql-statement-admin.md b/sql-statements/sql-statement-admin.md
@@ -11,6 +11,7 @@ This statement is a TiDB extension syntax, used to view the status of TiDB and c
 - [`ADMIN PLUGINS`](#admin-plugins-related-statement)
 - [`ADMIN ... BINDINGS`](#admin-bindings-related-statement)
 - [`ADMIN REPAIR`](#admin-repair-statement)
+- [`ADMIN SHOW NEXT_ROW_ID`](#admin-show-next_row_id-statement)
 - [`ADMIN SHOW SLOW`](#admin-show-slow-statement)
 
 ## DDL related statement
@@ -134,6 +135,14 @@ Here "untrusted" means that you need to manually ensure that the metadata of the
 
 </CustomContent>
 
+## `ADMIN SHOW NEXT_ROW_ID` statement
+
+```sql
+ADMIN SHOW t NEXT_ROW_ID;
+```
+
+The above statement is used to view the details of some special columns of a table. The output is the same as [SHOW TABLE NEXT_ROW_ID](/sql-statements/sql-statement-show-table-next-rowid.md).
+
 ## `ADMIN SHOW SLOW` statement
 
 {{< copyable "sql" >}}
@@ -210,6 +219,22 @@ ADMIN SHOW DDL JOBS 5;
 +--------+---------+------------+---------------------+----------------+-----------+----------+-----------+-----------------------------------+-----------------------------------+---------------+
 ```
 
+Run the following command to view the details of some special columns of a table. The output is the same as [SHOW TABLE NEXT_ROW_ID](/sql-statements/sql-statement-show-table-next-rowid.md).
+
+```sql
+ADMIN SHOW t NEXT_ROW_ID;
+```
+
+```sql
++---------+------------+-------------+--------------------+----------------+
+| DB_NAME | TABLE_NAME | COLUMN_NAME | NEXT_GLOBAL_ROW_ID | ID_TYPE        |
++---------+------------+-------------+--------------------+----------------+
+| test    | t          | _tidb_rowid |                101 | _TIDB_ROWID    |
+| test    | t          | _tidb_rowid |                  1 | AUTO_INCREMENT |
++---------+------------+-------------+--------------------+----------------+
+2 rows in set (0.01 sec)
+```
+
 Run the following command to view the uncompleted DDL jobs in the test database. The results include the DDL jobs that are running and the last 5 DDL jobs that are completed but failed.
 
 {{< copyable "sql" >}}