Cursor Optimization issue

Question

Hello everybody,
im a bit new in sql coding and i need your help to optimize a cursor i have created that seems (a bit - not much) slow. Any comments-suggestions are welcomed . Ty in Advance,
Mike
(the purpose of the cursor is to take multiple values from a buffer-tmp table from a remote mssql db to my oracle one and then divide them depending use in different tables... in detail these are customers that are performing some communications with some companies .... these comms are called OBD, the hard thing was that the remote system is totally different in architecture from mine... the cursor works fine but i believe it can be coded to be faster)
CREATE OR REPLACE PROCEDURE RETRIEVE_OBD_DATA4 (
comm_numEntries OUT NUMBER, comm_numUpdates OUT NUMBER, comm_numInserts OUT NUMBER,
lov_numEntries OUT NUMBER, lov_numUpdates OUT NUMBER, lov_numInserts OUT NUMBER,
pel_numEntries OUT NUMBER, pel_numUpdates OUT NUMBER, pel_numInserts OUT NUMBER) IS
l_indx1 NUMBER; l_comm1 char(600);l_code1 NUMBER;l_indx2 NUMBER;l_comm2 char(600);
l_code2 NUMBER;l_tmp1 NUMBER;
p_indx_id1 NUMBER;p_name1 char(400);p_surname1 char(400);p_address1 char(400);p_region1 char(800);
p_username1 char(400);p_brandname1 char(400);p_nomiki1 char(400);p_afm1 char(400);p_phone1 char(400);
p_fax1 char(800);p_drasti1 char(400);p_date1 char(200);p_gender1 char(400) ;p_tmp1 NUMBER;
c_tmp1 number; OBD_KWDIKOS1 char(800); OBD_ONOMA1 char(600); HMEROMHNIA_E1 char(200); SYMB1 number; LOC1 number; P_INDX_ID2 number;
CURSOR lov IS
SELECT OBD_KWDIKOS AS L_CODE, OBD_ONOMA AS L_COMM
FROM PORTAL.APOPSI_COMM_OBD
GROUP BY OBD_KWDIKOS, OBD_ONOMA;
CURSOR pelates IS
SELECT ONOMA AS P_NAME, EPWNYMO AS P_SURNAME, DIEUTHINSI AS P_ADDRESS, DHMOS AS P_REGION,
HMEROMHNIA_K AS P_DATE , DRASTHRIOTITA AS P_DRASTI,GENRE AS P_GENDER,
USERN AS P_USERNAME, EPWNYMIA AS P_BRANDNAME, NOMIKI AS P_NOMIKI, AFM AS P_AFM, THLEFWNO AS P_PHONE,FAX AS P_FAX
FROM PORTAL.APOPSI_COMM_OBD
GROUP BY ONOMA,EPWNYMO ,DIEUTHINSI ,DHMOS ,USERN ,EPWNYMIA ,NOMIKI ,AFM ,THLEFWNO ,FAX,HMEROMHNIA_K,DRASTHRIOTITA,GENRE;
CURSOR comm IS
SELECT O.OBD_KWDIKOS, O.OBD_ONOMA, O.HMEROMHNIA_E, O.SYMB, O.LOC, P.P_INDX_ID
FROM PORTAL.TMP_OBD O INNER JOIN PORTAL.TMP_COMM2 C ON C.ID = O.OBD_INDX INNER JOIN
PORTAL.APOPSI_COMM_PELATES P ON C.NAME = P.P_NAME AND C.SURNAME = P.P_SURNAME AND C.PHONE = P.P_PHONE;
BEGIN
DELETE FROM PORTAL.TMP_PELATES;
l_code1 := 0;
l_indx1 := 0;
l_code2 := 0;
l_indx2 := 0;
l_tmp1 := 0;
comm_numEntries := 0; comm_numUpdates := 0; comm_numInserts := 0;
lov_numEntries := 0; lov_numUpdates := 0; lov_numInserts := 0;
pel_numEntries := 0; pel_numUpdates := 0; pel_numInserts := 0;
p_tmp1 := 0; c_tmp1 := 0;
OPEN lov;
OPEN pelates;
OPEN comm;
LOOP
FETCH lov INTO l_code1,l_comm1;
EXIT WHEN lov%NOTFOUND;
lov_numEntries := lov_numEntries + 1;
SELECT COUNT(*) INTO l_tmp1 FROM PORTAL.APOPSI_COMM_COMM2_LOV WHERE L_CODE = TO_CHAR(l_code1) AND L_COMM = l_comm1;
SELECT (MAX(L_INDX)+1) INTO l_indx1 FROM PORTAL.APOPSI_COMM_COMM2_LOV;
IF l_tmp1 = 0 THEN
lov_numInserts := lov_numInserts + 1;
INSERT INTO PORTAL.APOPSI_COMM_COMM2_LOV(L_INDX,L_CODE,L_COMM) VALUES (l_indx1, TO_CHAR(l_code1), l_comm1);
INSERT INTO PORTAL.TMP_LOV(L_INDX,L_CODE,L_COMM, L_INSERT) VALUES (l_indx1, TO_CHAR(l_code1), l_comm1,1);
ELSE
IF l_tmp1 = 1 then
null;
else
lov_numUpdates := lov_numUpdates + 1;
DELETE FROM PORTAL.APOPSI_COMM_COMM2_LOV WHERE L_CODE = TO_CHAR(l_code1);
INSERT INTO PORTAL.APOPSI_COMM_COMM2_LOV(L_INDX,L_CODE,L_COMM) VALUES (l_indx1, TO_CHAR(l_code1), l_comm1);
INSERT INTO PORTAL.TMP_LOV(L_INDX,L_CODE,L_COMM,L_INSERT) VALUES (l_indx1, TO_CHAR(l_code1), l_comm1,0);
end if;
END IF;
END LOOP;
LOOP
FETCH pelates INTO p_name1,p_surname1,p_address1,p_region1,p_date1,p_gender1, p_drasti1, p_username1, p_brandname1, p_nomiki1 ,p_afm1, p_phone1,p_fax1;
EXIT WHEN pelates%NOTFOUND;
pel_numEntries := pel_numEntries + 1;
SELECT (MAX(P_INDX_ID) + 1) INTO p_indx_id1 FROM PORTAL.APOPSI_COMM_PELATES;
SELECT COUNT(*) INTO p_tmp1 FROM PORTAL.APOPSI_COMM_PELATES WHERE P_NAME = p_name1 AND P_SURNAME = p_surname1;
IF p_tmp1 = 0 THEN
pel_numInserts := pel_numInserts + 1;
INSERT INTO PORTAL.APOPSI_COMM_PELATES (P_DRASTI,P_DATE,P_IDIOTITA,p_gender,P_INDX_ID,p_name,p_surname,p_address,p_region, p_username, p_brandname ,p_nomiki ,p_afm, p_phone,p_fax)
VALUES (p_drasti1,p_date1,' ',p_gender1,P_INDX_ID1, p_name1,p_surname1,p_address1,p_region1, p_username1, p_brandname1 ,p_nomiki1 ,p_afm1, p_phone1,p_fax1);
INSERT INTO PORTAL.TMP_PELATES (P_DRASTI,P_DATE,P_IDIOTITA,p_gender,P_INDX_ID, p_name,p_surname,p_address,p_region, p_username, p_brandname ,p_nomiki ,p_afm, p_phone,p_fax, P_INSERT)
VALUES (p_drasti1,p_date1,' ',p_gender1,P_INDX_ID1, p_name1,p_surname1,p_address1,p_region1, p_username1, p_brandname1 ,p_nomiki1 ,p_afm1, p_phone1,p_fax1, 1);
ELSE
if p_tmp1 = 1 THEN
NULL;
ELSE
pel_numUpdates := pel_numUpdates + 1;
DELETE FROM PORTAL.APOPSI_COMM_PELATES WHERE P_NAME = p_name1 AND P_SURNAME = p_surname1;
INSERT INTO PORTAL.APOPSI_COMM_PELATES (P_DRASTI,P_DATE,P_IDIOTITA,p_gender,P_INDX_ID,p_name,p_surname,p_address,p_region, p_username, p_brandname ,p_nomiki ,p_afm, p_phone,p_fax)
VALUES (p_drasti1,p_date1,' ',p_gender1, P_INDX_ID1, p_name1,p_surname1,p_address1,p_region1, p_username1, p_brandname1 ,p_nomiki1 ,p_afm1, p_phone1,p_fax1);
INSERT INTO PORTAL.TMP_PELATES (P_DRASTI,P_DATE,P_IDIOTITA,p_gender,P_INDX_ID, p_name,p_surname,p_address,p_region, p_username, p_brandname ,p_nomiki ,p_afm, p_phone,p_fax, P_INSERT)
VALUES (p_drasti1,p_date1,' ',p_gender1,P_INDX_ID1, p_name1,p_surname1,p_address1,p_region1, p_username1, p_brandname1 ,p_nomiki1 ,p_afm1, p_phone1,p_fax1,0);
END IF;
END IF;
END LOOP;
LOOP
FETCH comm INTO OBD_KWDIKOS1,OBD_ONOMA1,HMEROMHNIA_E1,SYMB1,LOC1, P_INDX_ID2;
EXIT WHEN comm%NOTFOUND;
comm_numEntries := comm_numEntries + 1;
SELECT COUNT(*) INTO c_tmp1 FROM PORTAL.APOPSI_COMM_OBD_LOCAL O WHERE O.OBD_CODE = OBD_KWDIKOS1 AND
O.OBD_NAME = OBD_onoma1 AND O.OBD_DATE = HMEROMHNIA_E1 AND O.PEL_ID = P_INDX_ID2;
IF c_tmp1 = 0 THEN
comm_numInserts := comm_numInserts + 1;
INSERT INTO PORTAL.APOPSI_COMM_OBD_LOCAL
VALUES (OBD_KWDIKOS1,OBD_ONOMA1,HMEROMHNIA_E1,SYMB1,LOC1, P_INDX_ID2);
ELSE
if c_tmp1 = 1 THEN
NULL;
ELSE
comm_numUpdates := comm_numUpdates + 1;
DELETE FROM PORTAL.APOPSI_COMM_OBD_LOCAL O WHERE O.OBD_CODE = OBD_KWDIKOS1 AND
O.OBD_NAME = OBD_onoma1 AND O.OBD_DATE = HMEROMHNIA_E1 AND O.PEL_ID = P_INDX_ID2;
INSERT INTO PORTAL.APOPSI_COMM_OBD_LOCAL
VALUES (OBD_KWDIKOS1,OBD_ONOMA1,HMEROMHNIA_E1,SYMB1,LOC1, P_INDX_ID2);
END IF;
END IF;
END LOOP;
CLOSE comm;
CLOSE lov;
CLOSE pelates;
END RETRIEVE_OBD_DATA4;
/

Answer 1

Well, to answer myself it turns out that cursors of the form "OPEN - LOOP - EXIT WHEN %NOTFOUND - END LOOP - CLOSE" are not converted to the bulk-collect equivalent, as "FOR rec IN (cursor) LOOP" ones are from 10g R2 onwards (tests below use 11.1.0.6.0).
Implicit (1 fetch):
DECLARE
    i INTEGER := 0;
BEGIN
    FOR r IN ( SELECT * FROM scott.emp )
    LOOP
        i := i + r.empno;
    END LOOP;
END;
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           1
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          0          0          0           1
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 88 
SQL ID : 5vms4mrz8j7wd
SELECT *
FROM
SCOTT.EMP
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch 1 0.00 0.00 0 7 0 14
total        3      0.00       0.00          0          7Explicit (15 fetches):
DECLARE
    i INTEGER := 0;
    CURSOR c_emp IS
        SELECT * FROM scott.emp;
    r_emp c_emp%ROWTYPE;
BEGIN
    OPEN c_emp;
    LOOP
        FETCH c_emp INTO r_emp;
        EXIT WHEN c_emp%NOTFOUND;
        i := i + r_emp.empno;
    END LOOP;
    CLOSE c_emp;
END;
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           1
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          0          0          0           1
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 88 
SQL ID : 4ay6mhcbhvbf2
SELECT *
FROM
SCOTT.EMP
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.01       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch 15 0.00 0.00 0 20 0 14
total       17      0.01       0.00          0         20          0          14or another example:
DECLARE
    i INTEGER := 0;
BEGIN
    FOR r IN ( SELECT 1 n FROM dual CONNECT BY rownum < 999 )
    LOOP
        i := i + r.n;
    END LOOP;
END;
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           1
Fetch        0      0.00       0.00          0          0          0           0
total        2      0.00       0.00          0          0          0           1
Misses in library cache during parse: 0
Optimizer mode: ALL_ROWS
Parsing user id: 88 
SQL ID : caf6v3bbkvqkk
SELECT 1 N
FROM
DUAL CONNECT BY ROWNUM < 999
call     count       cpu    elapsed       disk      query    current        rows
Parse        1      0.00       0.00          0          0          0           0
Execute      1      0.00       0.00          0          0          0           0
Fetch 10 0.00 0.00 0 0 0 998
total       12      0.00       0.00          0          0          0         998So in code like the OP's example procedure it is explicit cursors that perform the extra fetch and not implicit ones, and this could help explain why implicit cursors perform better.