서버커리에 들어가는데...속도가 너무 느려요.

무엇을 챙겨 봐야 할까요?

SELECT  MAX(NVL(NO, ERE_NO)) NO
                  FROM MAST X
                 WHERE X.P_NO = 'CFFGS'
                   AND SUBSTR(X.STG,1,1) = '4'
                 START WITH X.P_NO = 'CFFGS'
                   AND X.NO = 'AP16'
                CONNECT BY PRIOR X.PRNT_NO = X.NO ;
               
인덱스 구성               
MAST_PK (P_NO,NO)
MAST_AK3(P_NO,NO,PRNT_NO,STG,ERE_NO)

ID PID             Operation                                                 Name                             Rows                             Bytes                         Cost           CPU        Cost IO             Cost
0                      SELECT STATEMENT  1  29  54  371004  52
1 0                    SORT AGGREGATE  1  29      
2 1                           FILTER           
3 2                              CONNECT BY WITH FILTERING           
4 3                                 INDEX RANGE SCAN SHI1.CMCTB_BLK_MAST_AK3 1  26  1  5391  1
5 3                                     NESTED LOOPS  20  600  51  365613  51
6 5                                        CONNECT BY PUMP           
7 5                                              TABLE ACCESS BY INDEX ROWID SHI1.CMCTB_BLK_MAST 20  520  50  360222  50
8 7                                                 INDEX SKIP SCAN SHI1.CMCTB_BLK_MAST_PK 20    48  342829  48