docs: add-fix-index-acceleration-compatibility (#11861) (#11864)

releases/release-6.5.0.md

@@ -354,7 +354,7 @@ Compared with the previous LTS 6.1.0, 6.5.0 not only includes new features, impr
 ### Others
 
 - Starting from v6.5.0, the `mysql.user` table adds two new columns: `Password_reuse_history` and `Password_reuse_time`.
-- The [index acceleration](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630) feature is enabled by default and is not compatible with the [PITR (Point-in-time recovery)](/br/br-pitr-guide.md) feature. When using the index acceleration feature, you need to make sure that no PITR backup task is running in the background; otherwise, unexpected results might occur. For more information, see [documentation](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630).
+- Starting from v6.5.0, the [index acceleration](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630) feature is enabled by default. This feature is not fully compatible with [altering multiple columns or indexes in a single `ALTER TABLE` statement](/sql-statements/sql-statement-alter-table.md). When adding a unique index with the index acceleration, you need to avoid altering other columns or indexes in the same statement. This feature is incompatible with [PITR (Point-in-time recovery)](/br/br-pitr-guide.md) either. When using the index acceleration feature, you need to make sure that no PITR backup task is running in the background; otherwise, unexpected results might occur. For more information, see [documentation](/system-variables.md#tidb_ddl_enable_fast_reorg-new-in-v630).
 
 ## Deprecated feature
 

system-variables.md

@@ -1105,6 +1105,9 @@ MPP is a distributed computing framework provided by the TiFlash engine, which a
 
 > **Warning:**
 >
+>
+> Currently, this feature is not fully compatible with [altering multiple columns or indexes in a single `ALTER TABLE` statement](/sql-statements/sql-statement-alter-table.md). When adding a unique index with the index acceleration, you need to avoid altering other columns or indexes in the same statement.
+>
 > Currently, this feature is not compatible with [PITR (Point-in-time recovery)](/br/backup-and-restore-overview.md). When using index acceleration, you need to ensure that there are no PITR log backup tasks running in the background. Otherwise, unexpected behaviors might occur, including:
 >
 > - If you start a log backup task before adding an index, the adding index process is not accelerated even if index acceleration is enabled. But the index is added in a slow way. Because the log backup task keeps running after being started, it means that the index acceleration feature is disabled in this case. To accelerate the process of adding an index, you can stop the log backup background task first, start and complete the index adding task, and then restart the log backup task and perform a full backup.