Performance of Database

Question

Hi all ,
I a, having 9.2.0.6.0. database.
when developers executes some batch job(running around 1 hour).They are saying it is responding very slow.Which view i need to check what wait events are there and caluse of slowness .Like where i need to find the cause .
V$waitstat
V$session_wait
V$system_event
which view (column) i need to go for...steps
can u put some light on it .
Thanks
Rohit Mathur

Answer 1

first look at which sqls are active and running on database:
set lines 233
select /*+ ordered */ to_char(s.sid,'99999'),
substr(username,1,8),
substr(t.sql_text,1,60),
nvl(last_call_et,0) TIME_sec,
t.hash_value,
substr(w.event,1,30) WAIT_EV,
substr(machine,1,10) MACHINE
from v$session s,v$sqltext t,v$session_wait w
where s.sql_address=t.address
and s.sql_HASH_VALUE=t.HASH_VALUE
and w.sid=s.sid
and username between 'AAAAAAAAA' and 'ZZZZZZZZZ'
and s.status='ACTIVE'
and t.piece=0
--and upper(sql_text) not like 'BEGIN%'
order by TIME_SEC
For the ones with high TIME_SEC value, run following script put its HASH_VALUE as input to see execution plan:
UNDEFINE H_VALUE
select
to_char(ID,'999') ID,substr(LPAD(' ',depth,' ')||OPERATION||' '||OPTIONS,1,40) Operation,
substr(OBJECT_NAME,1,25) Name,
substr(OPTIMIZER,1,10) OPTIMIZER,
CARDINALITY ,
Bytes,
Cost
from
v$sql_plan
where
HASH_VALUE=&&H_VALUE
--and child_number=0
order by
child_number,ID
select
to_char(ID,'999')||'- Filter: '||FILTER_PREDICATES ACCESS_FILTER
from
v$sql_plan
where
HASH_VALUE=&&H_VALUE and FILTER_PREDICATES is not null and FILTER_PREDICATES <> ' '
union
select
to_char(ID,'999')||'- Access: '||ACCESS_PREDICATES ACCESS_FILTER
from
v$sql_plan
where
HASH_VALUE=&H_VALUE and ACCESS_PREDICATES is not null --and ACCESS_PREDICATES <> ' '
order by ACCESS_FILTER
however, if batch job runs thousands of short TIME_sec sqls, then this method is useless. In this case you should check executions column of v$sqlarea view in order to see if there is a huge increase in execution number of any sql. Then you should focus on those sqls.
regards,
erkan