lock contention please

[andemg]

hi all,
can anybody please tell me how to find out lock contention? Are there any scripts available to know this? i'll be very thankful to any advices regarding this.
venu!

[julian]

OPS locking problems or normal Oracle?

If it is OPS then it is not that simpe to explain. For a single env, run this for example:

set linesize 132 pagesize 66
break on Kill on username on terminal
column Kill heading 'Kill String' format a13
column res heading 'Resource Type' format 999
column id1 format 9999990
column id2 format 9999990
column lmode heading 'Lock Held' format a20
column request heading 'Lock Requested' format a20
column serial# format 99999
column username format a10 heading "Username"
column terminal heading Term format a6
column tab format a35 heading "Table Name"
column owner format a9
column Address format a18
select nvl(S.USERNAME,'Internal') username,
nvl(S.TERMINAL,'None') terminal,
L.SID||','||S.SERIAL# Kill,
U1.NAME||'.'||substr(T1.NAME,1,20) tab,
decode(L.LMODE,1,'No Lock',
2,'Row Share',
3,'Row Exclusive',
4,'Share',
5,'Share Row Exclusive',
6,'Exclusive',null) lmode,
decode(L.REQUEST,1,'No Lock',
2,'Row Share',
3,'Row Exclusive',
4,'Share',
5,'Share Row Exclusive',
6,'Exclusive',null) request
from V$LOCK L,
V$SESSION S,
SYS.USER$ U1,
SYS.OBJ$ T1
where L.SID = S.SID
and T1.OBJ# = decode(L.ID2,0,L.ID1,L.ID2)
and U1.USER# = T1.OWNER#
and S.TYPE != 'BACKGROUND'
order by 1,2,5
/

[sambavan]

Check the following views
http://technet.oracle.com/docs/produ...ch380.htm#5397
http://technet.oracle.com/docs/produ...h383.htm#46175

Also refer utllockt.sql script under $ORACLE_HOME/rdbms/admin.


Sam

[rohitsn]

Hi,
The following is the script to find out lock contention.There are only 3 locks which a DBA can tune i.e redo copy,redo allocation and redo writing.The ratio of all this 3 types of locks ie.(misses/gets)*100 and (immediate_misses/immediate_gets)*100 should be less than < 1%.

select substr(c.name,1,30),a.gets,a.misses,a.sleeps, a.immediate_gets,a.immediate_misses,b.pid
from v$latch a, v$latchholder b, v$latchname c
where a.addr = b.laddr(+)
and a.latch# = c.latch#
and (c.name like 'redo%' or c.name like 'row%' )
order by a.latch#

In case of any help please be free to ask me at rohitsn@altavista.com

Regards,
Rohit Nirkhe,Oracle DBA,OCP 8i
rohitsn@altavista.com

[andemg]

thank you julian and thank you sam, i was referring to a non-OPS database. but i think the scrpit julian has provided will serve the purpose. thanks a lot ppl.

[andemg]

nice script rohit! thanks a lot!