Hi Team,
I have a select for update query like below.
select c1,c2 from tab1 where c1= 100 for update;
I have queried the V$ACTIVE_SESSION_HISTORY dynamic view. In the time waited column its showing some amount of time.
Below is the output from V$ACTIVE_SESSION_HISTORY:
SESSION_ID SQL_ID SQL_CHILD_NUMBER SESSION_TY SESSION BLOCKING_SESSION BLOCKING_SE EVENT EVENT_ID WAIT_CLASS TIME_WAITED
---------- ------------- ---------------- ---------- ------- ---------------- ----------- ---------------------------------------------------------------- ---------- ---------------------------------------------------------------- -----------
5259 39m7f1a752hs7 0 FOREGROUND WAITING NO HOLDER db file sequential read 2652584166 User I/O 35208
Here the time waited is 35208.
My question is:
1) is there any session or the transaction which is blocking this transaction.? if yes then in which dynamic view i will get the details.
2) Does select for update causes any performance issues