update doc related to fast-create

accelerated-table-creation.md

@@ -8,9 +8,9 @@ aliases: ['/tidb/dev/ddl-v2/']
 
 TiDB v7.6.0 introduces the system variable [`tidb_ddl_version`](https://docs.pingcap.com/tidb/v7.6/system-variables#tidb_enable_fast_create_table-new-in-v800) to support accelerating table creation, which improves the efficiency of bulk table creation. Starting from v8.0.0, this system variable is renamed to [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800).
 
-TiDB uses the online asynchronous schema change algorithm to change the metadata. All DDL jobs are submitted to the `mysql.tidb_ddl_job` table, and the owner node pulls the DDL job to execute. After executing each phase of the online DDL algorithm, the DDL job is marked as completed and moved to the `mysql.tidb_ddl_history` table. Therefore, DDL statements can only be executed on the owner node and cannot be linearly extended.
+When accelerated table creation is enabled via [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800), table creation statements with the same schema committed to the same TiDB node at the same time are merged into batch table creation statements to improve table creation performance. Therefore, to improve the table creation performance, try to connect to the same TiDB node, create tables with the same schema concurrently, and increase the concurrency appropriately.
 
-However, for some DDL statements, it is not necessary to strictly follow the online DDL algorithm. For example, the `CREATE TABLE` statement only has two states for the job: `none` and `public`. Therefore, TiDB can simplify the execution process of DDL, and executes the `CREATE TABLE` statement on a non-owner node to accelerate table creation.
+The merged batch table creation statements are executed within the same transaction, so if one statement of them fails, all of them will fail.
 
 > **Warning:**
 >
@@ -39,19 +39,3 @@ To disable performance optimization for creating tables, set the value of this v
 ```sql
 SET GLOBAL tidb_enable_fast_create_table = OFF;
 ```
-
-## Implementation principle
-
-The detailed implementation principle of performance optimization for table creation is as follows:
-
-1. Create a `CREATE TABLE` Job.
-
-   The corresponding DDL Job is generated by parsing the `CREATE TABLE` statement.
-
-2. Execute the `CREATE TABLE` job.
-
-   The TiDB node that receives the `CREATE TABLE` statement executes it directly, and then persists the table structure to TiKV. At the same time, the `CREATE TABLE` job is marked as completed and inserted into the `mysql.tidb_ddl_history` table.
-
-3. Synchronize the table information.
-
-   TiDB notifies other nodes to synchronize the newly created table structure.

upgrade-tidb-using-tiup.md

@@ -21,6 +21,7 @@ This document is targeted for the following upgrade paths:
 > 3. **DO NOT** upgrade a TiDB cluster when a DDL statement is being executed in the cluster (usually for the time-consuming DDL statements such as `ADD INDEX` and the column type changes). Before the upgrade, it is recommended to use the [`ADMIN SHOW DDL`](/sql-statements/sql-statement-admin-show-ddl.md) command to check whether the TiDB cluster has an ongoing DDL job. If the cluster has a DDL job, to upgrade the cluster, wait until the DDL execution is finished or use the [`ADMIN CANCEL DDL`](/sql-statements/sql-statement-admin-cancel-ddl.md) command to cancel the DDL job before you upgrade the cluster.
 > 4. If the TiDB version before upgrade is 7.1.0 or later, you can ignore the preceding warnings 2 and 3. For more information, see [limitations on using TiDB smooth upgrade](/smooth-upgrade-tidb.md#limitations).
 > 5. Be sure to read [limitations on user operations](/smooth-upgrade-tidb.md#limitations-on-user-operations) before upgrading your TiDB cluster using TiUP.
+> 6. If the version of your current TiDB cluster is TiDB v7.6.0 to v8.2.0, the upgrade target version is v8.3.0 or later, and accelerated table creation is enabled via [`tidb_enable_fast_create_table`](/system-variables.md#tidb_enable_fast_create_table-new-in-v800), you need to first disable the accelerated table creation feature, and then enable it as needed after the upgrade is completed. Otherwise, some metadata KVs added by this feature remain in the cluster. Starting from v8.3.0, this feature is optimized. Upgrading to a later TiDB version no longer generates and retains this type of metadata KVs.
 
 > **Note:**
 >