Update docs related to locking (#19248)

pingcap · Nov 5, 2024 · 0063fb2 · 0063fb2
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diff --git a/information-schema/information-schema-data-lock-waits.md b/information-schema/information-schema-data-lock-waits.md
@@ -7,14 +7,12 @@ summary: Learn the `DATA_LOCK_WAITS` information_schema table.
 
 The `DATA_LOCK_WAITS` table shows the ongoing lock-wait information on all TiKV nodes in a cluster, including the lock-wait information of pessimistic transactions and the information of optimistic transactions being blocked.
 
-{{< copyable "sql" >}}
-
 ```sql
 USE information_schema;
 DESC data_lock_waits;
 ```
 
-```sql
+```
 +------------------------+---------------------+------+------+---------+-------+
 | Field                  | Type                | Null | Key  | Default | Extra |
 +------------------------+---------------------+------+------+---------+-------+
@@ -71,13 +69,11 @@ In the above fields, if the information of a field is not applicable or currentl
 
 ## Example
 
-{{< copyable "sql" >}}
-
 ```sql
 select * from information_schema.data_lock_waits\G
 ```
 
-```sql
+```
 *************************** 1. row ***************************
                    KEY: 7480000000000000355F728000000000000001
               KEY_INFO: {"db_id":1,"db_name":"test","table_id":53,"table_name":"t","handle_type":"int","handle_value":"1"}
@@ -89,3 +85,17 @@ CURRENT_HOLDING_TRX_ID: 426790590082449409
 ```
 
 The above query result shows that the transaction of the ID `426790594290122753` is trying to obtain the pessimistic lock on the key `"7480000000000000355F728000000000000001"` when executing a statement that has digest `"38b03afa5debbdf0326a014dbe5012a62c51957f1982b3093e748460f8b00821"` and  is in the form of ``update `t` set `v` = `v` + ? where `id` = ?``, but the lock on this key was held by the transaction of the ID `426790590082449409`.
+
+## See also
+
+<CustomContent platform="tidb">
+
+- [Troubleshoot Lock Conflicts](/troubleshoot-lock-conflicts.md)
+
+</CustomContent>
+
+<CustomContent platform="tidb-cloud">
+
+- [Handle Transaction Errors](/develop/dev-guide-transaction-troubleshoot.md)
+
+</CustomContent>
diff --git a/mysql-schema/mysql-schema.md b/mysql-schema/mysql-schema.md
@@ -84,8 +84,8 @@ Currently, the `help_topic` is NULL.
 
 ## 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
+* `tidb_mdl_view`: a view of metadata locks. You can use it to view information about the currently blocked DDL statements. See also [Metadata Lock](/metadata-lock.md).
+* `tidb_mdl_info`: used internally by TiDB to synchronize metadata locks across nodes.
 
 ## System tables related to DDL statements
 

diff --git a/troubleshoot-lock-conflicts.md b/troubleshoot-lock-conflicts.md
@@ -159,6 +159,12 @@ In the above query, the [`TIDB_DECODE_SQL_DIGESTS`](/functions-and-operators/tid
 
 If the `start_ts` of the current transaction is unknown, you can try to find it out from the information in the `TIDB_TRX` / `CLUSTER_TIDB_TRX` table or in the [`PROCESSLIST` / `CLUSTER_PROCESSLIST`](/information-schema/information-schema-processlist.md) table.
 
+### Metadata locks
+
+If a session is waiting on a schema change, this can be because of a metadata lock.
+
+See [Metadata Lock](/metadata-lock.md) for more information.
+
 ## Troubleshoot optimistic lock conflicts
 
 This section provides the solutions of common lock conflict issues in the optimistic transaction mode.