Hello Experts,
I am learning performance tuning concept from youtube videos in that i had some doubts.
Doubt 1:
scott user update the row sal=950+2 of empno 7900
as the hr use have rights select ,update on scott.emp so he also trying to update the row sal=950-5 of empno 7900
so i check problem (wait event) occurred through dynamic views through V$Session,V$sysstat,V$sql i found user scott only having row lock of emp table where empno=7900 and hr is waiting for that table row
What should i do? And what is our next step in real time?
Doubt 2: What are the real time performance tuning issues?
Please guide me.
Thanks in advance.
For doubt 1: It is called blocking sessions. In that case you can try some of below options .
1: tune the blocking sessions
or
2: kill the blocking session.
you can use below command to see blocking sessions:
select s1.INST_ID,s1.username || '@' || s1.machine
|| ' ( SID=' || s1.sid || ' ) is blocking '
|| s2.username || '@' || s2.machine || ' ( SID=' || s2.sid || ' ) ' AS blocking_status
from gv$lock l1, gv$session s1, gv$lock l2, gv$session s2
where s1.sid=l1.sid and s2.sid=l2.sid
and l1.BLOCK=1 and l2.request > 0
and l1.id1 = l2.id1
and l2.id2 = l2.id2;