diff --git a/proto/greptime/v1/ddl.proto b/proto/greptime/v1/ddl.proto
index 7381d36e..031cb4e8 100644
--- a/proto/greptime/v1/ddl.proto
+++ b/proto/greptime/v1/ddl.proto
@@ -147,7 +147,6 @@ message DropDatabaseExpr {
 
 message AddColumns {
   repeated AddColumn add_columns = 1;
-  bool add_if_not_exists = 2;
 }
 
 message DropColumns { repeated DropColumn drop_columns = 1; }
@@ -159,6 +158,7 @@ message RenameTable { string new_table_name = 1; }
 message AddColumn {
   ColumnDef column_def = 1;
   AddColumnLocation location = 3;
+  bool add_if_not_exists = 4;
 }
 
 message ModifyColumnType {