Process seems hanged

Question

Hi,
Aix 5.3
DB 10.2.0.2
Application Oracle Retek
Whenever a user try to update the filed from the application it seems hanged When i trace that session query there is below query is running and what i observed the same session is locking itself because when i try to look locking there is only one session that is the same user is using.
MERGE INTO RPM_FUTURE_RETAIL_GTT RFRG1 USING
(SELECT /*+ cardinality(pr 1000) */ RFRG.*, PROM.PROMO_COMP_DETAIL_ID RPCD_ID FROM
RPM_FUTURE_RETAIL_GTT RFRG, (SELECT DISTINCT
PR.PROMO_COMP_DETAIL_ID FROM TABLE(CAST(:B1 AS OBJ_RPM_CC_PROMO_TBL)) PR)
PROM WHERE RFRG.PRICE_EVENT_ID = PROM.PROMO_COMP_DETAIL_ID AND
(P1_C1_DETAIL_ID = PROM.PROMO_COMP_DETAIL_ID OR P1_C2_DETAIL_ID =
PROM.PROMO_COMP_DETAIL_ID OR P1_EXCLUSION1_ID =
PROM.PROMO_COMP_DETAIL_ID OR P1_EXCLUSION2_ID =
PROM.PROMO_COMP_DETAIL_ID OR P2_C1_DETAIL_ID =
PROM.PROMO_COMP_DETAIL_ID OR P2_C2_DETAIL_ID =
PROM.PROMO_COMP_DETAIL_ID OR P2_EXCLUSION1_ID =
PROM.PROMO_COMP_DETAIL_ID OR P2_EXCLUSION2_ID =
PROM.PROMO_COMP_DETAIL_ID)) PR ON
( RFRG1.PRICE_EVENT_ID =
PR.PRICE_EVENT_ID AND RFRG1.ITEM =
PR.ITEM AND RFRG1.LOCATION =
PR.LOCATION AND RFRG1.ACTION_DATE = PR.ACTION_DATE)
WHEN MATCHED THEN UPDATE SET PROMOTION1_ID =
DECODE(1, DECODE(NULL, P1_C1_DETAIL_ID, 0, 1)
+ DECODE(NULL, P1_C2_DETAIL_ID, 0, 1) + DECODE(NULL, P1_EXCLUSION1_ID, 0
Thanks,

Answer 1

If I am running an UPDATE statement, which because of it's predicates, will update 15 records, my process will start locking and updating the records. If it finds that the 12th record is locked by another session, it will wait. (It will not even then attempt to check the 13th, 14th or 15th records which may all not be locked or may be locked by other sessions !).
The specific columns (BLOCKING_SESSSION, EVENT, P1, P2, P3, ROW_WAIT_OBJ#, ROW_WAIT_FILE#, ROW_WAIT_BLOCK#, ROW_WAIT_ROW#) should help identify if the waiting session (the one that "seems hanged") is waiting on a row lock.
Querying V$SESSION_WAIT should help identify what event it is waitng for at that point in time !. It might not be waiting for a Row Lock but just be running very slowly, waiting for Disk I/O on, say, 15000 rows.
Hemant K Chitale