How to build a lock escalation tree?

Question

Hello!
Concurrent users lock many rows in different tables. Sometimes
one session waits to lock row, which is locked by another
session.
Locks are made by SQL statements.
I would like to present tree of SQL statements which lock (first
level) and as children SQL - statements waiting for release lock
by their parents.
It would be very helpul in finding dependencies and app places,
where deadlock can occur.
Do you know system SQL statement or tool, which could produce
result I need?
TIA,
Witek

Answer 1

I modified the script I posted earlier to include the waiters SQL
statement. You'll have to verify that this is what you're looking
for and that it's correct. I did some simple testing and it
seemed to work.
set term off;
set null ~;
set arraysize 10
drop table lock_holders;
drop table dba_locks_temp;
create table dba_locks_temp as select * from dba_locks;
create table lock_holders as
select w.session_id waiting_session,
h.session_id holding_session,
w.lock_type,
h.mode_held,
w.mode_requested,
w.lock_id1,
w.lock_id2,
a.sql_text sql_stmnt
from dba_locks_temp w, dba_locks_temp h, v$session s, v$sqltext
a
where h.blocking_others = 'Blocking'
and h.mode_held != 'None'
and h.mode_held != 'Null'
and w.mode_requested != 'None'
and w.lock_type = h.lock_type
and w.lock_id1 = h.lock_id1
and w.lock_id2 = h.lock_id2
and w.session_id=s.sid(+)
and s.sql_address = a.address
and s.status = 'ACTIVE'
and s.type !='BACKGROUND'
order by a.address
,a.piece;
commit;
drop table dba_locks_temp;
insert into lock_holders
select holding_session, null, 'None', null, null, null, null,
null
from lock_holders
minus
select waiting_session, null, 'None', null, null, null, null,
null
from lock_holders;
commit;
/* set charwidth 17; */
set wrap off;
set term on;
select substr(lpad(' ',3*(level-1)) ||
substr(waiting_session,1,10),1,20)
waiting_session, sql_stmnt
from lock_holders
connect by prior waiting_session = holding_session
start with holding_session is null;
set term off;
drop table lock_holders;
set wrap on;
set term on;
Here's the output it generated from a test I ran:
WAITING_SESSION SQL_STMNT
9 ~
11 update emp set acct_segment1='1111111',
acct_segment2='2222222',
11 acct_segment3='3333333',
acct_segment4='4444444', acct_segment5
11 ='5555555', acct_segment6='6666666' where
employee='AGLICK'
If you wanted you could also add username and osuser from
v$session to get the users Oracle userid and their network id.