Oracle未优化的读取请求

奇怪的是，这个查询在我的AWR报告中显示为“未优化”。我希望每个人都能帮助我了解性能上的差异

这是桌子

CREATE TABLE STGE_TABLE(
   FIELD_01 NUMBER, 
   FIELD_02 NUMBER, 
   FIELD_03 DATE, 
   BATCH_ID NUMBER
) PARTITION BY RANGE (BATCH_ID) INTERVAL(1)
  PARTITION EMPTY VALUES LESS THAN (0);

CREATE TABLE LIVE_TABLE(
   FIELD_01 NUMBER, 
   FIELD_02 NUMBER, 
   FIELD_03 DATE
);

这是包裹：

CREATE OR REPLACE PACKAGE MY_MERGE_PKG 
AS 
   PROCEDURE MERGE_MY_TWO_TABLES; 
END MY_MERGE_PKG;

CREATE OR REPLACE PACKAGE BODY MY_MERGE_PKG 
AS 
   PROCEDURE MERGE_MY_TWO_TABLES 
   AS 
   ln_batch_id number; 
   lc_queue_src varchar(10);
   BEGIN 
      LOOP 
      BEGIN 

         --GET THE NEXT BATCH_ID FROM THE QUEUE ALONG WITH THE lc_queue_src
         IF lc_queue_src = 'TYPE_01' THEN
            MERGE INTO LIVE_TABLE TGT
            USING (
               SELECT FIELD_01, FIELD_02, FIELD_03
               FROM STGE_TABLE
               WHERE BATCH_ID=ln_batch_id
            ) SRC
            ON (SRC.FIELD_01 = TGT.FIELD_01)
            WHEN MATCHED THEN
            UPDATE SET TGT.FIELD_03 = SRC.FIELD_03
            WHEN NOT MATCHED THEN
            INSERT(TGT.FIELD_01, TGT_FIELD_03)
            VALUES(SRC.FIELD_01, SRC.FIELD_03);
         ELSE
            MERGE INTO LIVE_TABLE TGT
            USING (
               SELECT FIELD_01, FIELD_02, FIELD_03
               FROM STGE_TABLE
               WHERE BATCH_ID=ln_batch_id
            ) SRC
            ON (SRC.FIELD_01 = TGT.FIELD_01)
            WHEN MATCHED THEN
            UPDATE SET TGT.FIELD_02 = SRC.FIELD_02
            WHEN NOT MATCHED THEN
            INSERT(TGT.FIELD_01, TGT_FIELD_02)
            VALUES(SRC.FIELD_01, SRC.FIELD_02);
         END IF;

      END; 
   END LOOP; 
END MERGE_MY_TWO_TABLES;

在AWR报告中，它显示中ELSE块中的合并未优化。我不太明白为什么它们实际上是相同的merge语句

非常感谢在这件事上给予的任何帮助