update MD by dispatch event pingcap/docs release-8.1

Author: github-actions

markdown-pages/en/tidb/release-8.1/ticdc/ticdc-data-replication-capabilities.md

@@ -48,3 +48,17 @@ TiCDC supports the following types of upstream data changes:
 - TiCDC only verifies the integrity of upstream data changes. It does not validate whether the changes conform to upstream or downstream constraints. If the data violates downstream constraints, TiCDC will return an error when writing to the downstream.
 
     For example: When a changefeed is configured to filter out all DDL events, if the upstream executes a `DROP COLUMN` operation but continues to write `INSERT` statements involving that column, TiCDC will fail to replicate these DML changes to the downstream because of table schema mismatches.
+
+- For the TiCDC [classic architecture](https://docs.pingcap.com/tidb/stable/ticdc-classic-architecture/), when the number of tables replicated by a single TiCDC cluster exceeds the following recommended values, TiCDC might not work stably:
+
+    | TiCDC version | Recommended number of tables to be replicated |
+    |---|:---:|
+    | v5.4.0 - v6.4.x | 2000 |
+    | v6.5.x - v7.4.x | 4000 |
+    | v7.5.x - v8.5.x | 40000 |
+
+    > **Note:**
+    >
+    > When replicating partitioned tables, TiCDC treats each partition as a separate table. Therefore, the partition count is included when TiCDC calculates the total number of tables to be replicated.
+
+    If the number of tables to be replicated exceeds the preceding recommended values, it is recommended to use the [TiCDC new architecture](https://docs.pingcap.com/tidb/stable/ticdc-architecture/). The new architecture supports replicating more than one million tables per changefeed, making it suitable for large-scale replication scenarios.

markdown-pages/en/tidb/release-8.1/tidb-upgrade-migration-guide.md

@@ -222,7 +222,7 @@ Additionally, you can scale out the new cluster to handle expected workloads and
     - After setting the old cluster to read-only mode, retrieve the current `up-tso`:
 
         ```sql
-        SELECT tidb_current_ts();
+        BEGIN; SELECT TIDB_CURRENT_TSO(); ROLLBACK;
         ```
 
     - Monitor the Changefeed `checkpointTs` to confirm it has surpassed `up-tso`, indicating that TiCDC has completed data replication.
@@ -268,7 +268,7 @@ Additionally, you can scale out the new cluster to handle expected workloads and
     2. Record the current TSO of the new cluster:
 
         ```sql
-        SELECT tidb_current_ts();
+        BEGIN; SELECT TIDB_CURRENT_TSO(); ROLLBACK;
         ```
 
     3. Configure the reverse replication link and ensure the Changefeed task is running properly: