[FEAT MERGE]:Oracle Json Supported

src/sql/engine/expr/ob_expr_json_merge_preserve.cpp

@@ -8,8 +8,10 @@
  * EITHER EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO NON-INFRINGEMENT,
  * MERCHANTABILITY OR FIT FOR A PARTICULAR PURPOSE.
  * See the Mulan PubL v2 for more details.
+ * This file is for implementation of func json_merge_preserve
  */
 
+
 #define USING_LOG_PREFIX SQL_ENG
 #include "ob_expr_json_merge_preserve.h"
 #include "sql/engine/expr/ob_expr_json_func_helper.h"