TX - row lock contention in SELECT query without update clause

Hi,
We are having problem in one of our application on production. The ASH report shows 'eq: Tx row lock contention' for only Select statements. There is no FOR UPDATE in the select statements. The exact statement is
enq: TX - row lock contention : SELECT COUNT (1) FROM Table1 WHERE col1= :1 AND col2= :1 AND col3= :1 AND ROWNUM = 1
enq: TX - row lock contention : SELECT MODULE_CD , MSG_DESC , SEVERITY FROM GS_ERROR_MSG WHERE MSG_NUM = :1
I don't know why the select are locking the table rows and resulting in waits..
Our environment is Oracle 10g and Forms & Reports..
Please help.
-- Prashant

Hi,
are you sure that there is no dml against the tables?
You can query v$active_session_history (eg column BLOCKING_SESSION) to see which session locked the row.
HTH..
- wiZ

Similar Messages

Enq: TX - row lock contention in Select without for update

We have deployed a new Version of our Software on the test-system of our customer.
While the software runs fine on our Systems (Oracle EE 10.2.0.4 as well as Oracle EE 11.2.0.2 on EL 5.4 x86_64) it runs sluggish on our Customer's system (Oracle EE 10.2.0.4 on Solaris 10 x64).
During analysis of the problem I came across this:
SQL ID: Plan Hash: 3934983510
SELECT ts.message_id_t235
FROM t235_time_series ts,
       t238_timeseries_reported tsr
WHERE ts.time_series_id_t235 = tsr.timeseries_id_t238
   AND tsr.message_id_t238 = :b2
   AND ts.current_state_t235 = :b1
   AND ROWNUM = 1
call     count       cpu    elapsed       disk      query    current        rows
======= ====== ======== ========== ========== ========== ========== ==========
Parse        0      0.00       0.00          0          0          0           0
Execute      8      0.01     *137.55*          0          8          5           0
Fetch        8      0.00       0.00          0         60          0           8
======= ====== ======== ========== ========== ========== ========== ==========
total       16      0.01     137.55          0         68          5           8
Misses in library cache during parse: 0
Optimizer mode: CHOOSE
Parsing user id: 90     (recursive depth: 1)
Elapsed times include waiting on following events:
Event waited on                             Times   Max. Wait Total Waited
========================================   Waited ========== ============
*enq:* *TX* *=* *row* *lock* *contention*                 281        0.64        *137.01*
********************************************************************************As you can see the statement is very primitive. The Tables used are very huge (100M+ Rows) but have no bitmap indexes. How can this statement wait on enq: TX = row lock contention?
Thanks in advance!
Best regards,
Sven
Edited by: user12182396 on Feb 4, 2011 5:43 AM
Edited by: user12182396 on Feb 4, 2011 6:02 AM

user12182396 wrote:
We have deployed a new Version of our Software on the test-system of our customer.
While the software runs fine on our Systems (Oracle EE 10.2.0.4 as well as Oracle EE 11.2.0.2 on EL 5.4 x86_64) it runs sluggish on our Customer's system (Oracle EE 10.2.0.4 on Solaris 10 x64).
During analysis of the problem I came across this:
SQL ID: Plan Hash: 3934983510
SELECT ts.message_id_t235
FROM t235_time_series ts,
t238_timeseries_reported tsr
WHERE ts.time_series_id_t235 = tsr.timeseries_id_t238
AND tsr.message_id_t238 = :b2
AND ts.current_state_t235 = :b1
AND ROWNUM = 1
call     count       cpu    elapsed       disk      query    current        rows
======= ====== ======== ========== ========== ========== ========== ==========
Parse        0      0.00       0.00          0          0          0           0
Execute      8      0.01     *137.55*          0          8          5           0
Fetch        8      0.00       0.00          0         60          0           8
======= ====== ======== ========== ========== ========== ========== ==========
total       16      0.01     137.55          0         68          5           8
Misses in library cache during parse: 0
Optimizer mode: CHOOSE
Parsing user id: 90     (recursive depth: 1)
Elapsed times include waiting on following events:
Event waited on                             Times   Max. Wait Total Waited
========================================   Waited ========== ============
*enq:* *TX* *=* *row* *lock* *contention*                 281        0.64        *137.01*
******************************************************************************** As you can see the statement is very primitive. The Tables used are very huge (100M+ Rows) but have no bitmap indexes. How can this statement wait on enq: TX = row lock contention?
Are either of these tables subject to distributed transactions through database links ? If so then it is possible for a select statement to wait on a TX enqueue in mode 4 if it's trying to read a block which is subject to change by another tranaction that is stuck between the PREPARE and COMMIT phases of a "2 phase commit".
However, I have to say that don't know whether this would show up as: "enq: TX - row lock contention" or "enq: TX - contention". If you monitor the system for a while - checking v$lock for lock types TX, or query v$active_session_history (if you're licensed to use it) you may be able to check the lock mode.
If this is the problem then it's generally indicative of a networking problem of some sort - possibly simple congestion because of excess traffic.
Regards
Jonathan Lewis
http://jonathanlewis.wordpress.com
http://www.jlcomp.demon.co.uk
To post code, statspack/AWR report, execution plans or trace files, START and END the text with the tag {noformat}{noformat} (the word "code" in lowercase, curly brackets, no spaces) so that the text appears in fixed format.
There is a +"Preview"+ tab at the top of the text entry panel. Use this to check what your message will look like before you post the message. If it looks a complete mess you're unlikely to get a response. (Click on the +"Plain text"+ tab if you want to edit the text to tidy it up.)

JDBC Sender - Select Query without Update Query

In this case, how many times data will be polled within some minutes, if my polling interval is 1 day.
How many messages in sxmb_moni?
Thanks,
Greg

>>In this case, how many times data will be polled within some minutes, if my polling interval is 1 day.
The communication channel executes once as soon as you activate your sender communication channel. Now a single msg is sent to XI(with many as many rows as the select query fetches from the db).
After that, it waits for the polling interval(in your case 24 hrs) and then executes again.
This cycle continues. If you resart the communication channel, the cycle is disrupted and a new cycle starts.
Hope I dont add to your confusion
Regards,
Jai Shankar

Index contention & row lock contention

Hi,
Recently our application loaded a handsome amount of data into our production database. The process took around 5 to 6 hours. During this process, we observed that the performance degraded.
The major wait events are
1) TX index contention (concurrency) and
2) ROW LOCK CONTENTION (application).
The sql which lead to index contention is a simple insert statement into a table x and row lock contention is into a table y.
Both x and y are major detail tables of our application. X has around 4 foreign keys, one foriegn key is referencing table y. the foreign key column x is indexed.
our database is on 10gR2 and using ASSM.
The data block wait event stats during the load process is as follows
select * from dba_hist_waitstat where snap_id between '21454' and '21462' AND WAIT_COUNT>0 and class='data block';
SNAP_ID DBID INSTANCE_NUMBER CLASS WAIT_COUNT TIME
21454 3937665896 1 data block 195089769 33899167
21455 3937665896 1 data block 195095958 33902183
21456 3937665896 1 data block 195096398 33902377
21457 3937665896 1 data block 195097225 33902843
21458 3937665896 1 data block 195628987 34037147
21459 3937665896 1 data block 195944006 34055524
21460 3937665896 1 data block 195944496 34055642
21461 3937665896 1 data block 196183308 34112433
21462 3937665896 1 data block 196213292 34127409
9 rows selected.
select snap_id,eq_type,req_reason, total_req#, total_wait#,failed_req#, cum_wait_time from dba_hist_enqueue_stat where snap_id between '21454' and '21462' and failed_req#>0 and eq_type='TM'
SYS@sqdb AS SYSDBA> /
SNAP_ID EQ REQ_REASON TOTAL_REQ# TOTAL_WAIT# FAILED_REQ# CUM_WAIT_TIME
21454 TM contention 682928465 14 2735 1750
21455 TM contention 682939964 14 2735 1750
21456 TM contention 682950668 14 2735 1750
21457 TM contention 682967980 14 2735 1750
21458 TM contention 682983109 14 2735 1750
21459 TM contention 682998136 14 2735 1750
21460 TM contention 683006816 14 2735 1750
21461 TM contention 683018179 14 2735 1750
21462 TM contention 683432945 14 2735 1750
9 rows selected.
I dont see any significant ITL contention on these objects compared to other contention. (from segment statistics)
SYS@sqdb AS SYSDBA> select b.object_name,a.snap_id, a.physical_writes_total,a.physical_writes_delta,a.physical_reads_total,a.physical_reads_delta, a.itl_waits_total,a.itl_waits_delta from dba_hist_seg_stat a,(select object_id,object_name from dba_objects where owner='ABCD') b where snap_id between '21454' and '21462' and a.obj#= b.object_id and a.itl_waits_delta> 0 order by itl_waits_delta,2,1;
OBJECT_NAME SNAP_ID PHYSICAL_WRITES_TOTAL PHYSICAL_WRITES_DELTA PHYSICAL_READS_TOTAL PHYSICAL_READS_DELTA ITL_WAITS_TOTAL ITL_WAITS_DELTA
IX4_Y 21462 37958 169 105668 174 38 1
IX4_X 21462 102380 1480 147196 5780 56 1
As per the application design, for each row of Y, there are multiple number of rows in X and it varies. What additional information do you think I should be collecting and any tips to fix the issue?
Thanks,
Murthy

hi
Are you using in your insert statement something like "SELECT ... FOR UPDATE"
post the result of this query during the error:
SELECT * FROM DBA_BLOCKERS;
SELECT * FROM DBA_WAITERS;

Heavy row lock contention

Guys,
I really appreciate your views on this.. Please can some one who have worked on RAC and have an understanding how RAC works, guide me.
We currently are running a loadtest on one of the new RAC system and we are seeing excessive row lock contention for one table. The table basically has very few rows, say about 6-8 and pretty much every user uses this table to lock rows before fetching some data from other tables. When have a heavy load, we see very high wait on this table and enq TX : Row lock contention.
What is the best way to avoid this ? Is there anyway, we can modify the design of the application and ensure locking.. The typical query that locks the rows in the table looks like this
SELECT WL0.CLUB_NAME, WL0.SCHEDULE_ID FROM VF_BINGO_NEXT_CLUB_DRAW WL0 WHERE ( WL0.CLUB_NAME = :1 ) FOR UPDATE As said, they table has only 6-8 rows, so query plan etc doesn't apply. Please can someone who have extensive application knowledge guide me thru ?
Many thanks in advance.
G

> But is there a way to alliviate the concurrency issue, if there is a genuine
requirement to hold lock on a table. What other options do we have other
than locking ?
The purpose of a lock is to ensure data consistency - only 1 process can change that row. So what I find puzzling is why so many app sessions want to change that single row. What data does that row hold that requires continual change? Just what is the purpose of this data if it is consistently and continually changing? What business requirement does it attempt to solve?
To be honest, this sounds like a major design problem to me.
Like the surrogate key generator approach I mentioned. You create a PK_SEQUENCE table with columns (tablename, pk_value). Any insert against a table requires a lock on PK_SEQUENCE for the table being inserted into - a read of the PK_VALUE, incrementing it by one and then updating that row with the latest sequence. This way each INSERT gets a "nice sequential number" to use as surrogate key for new rows.
Even when this is done as an autonomous transaction, it introduces a very expensive resource - why? Because only one session at a time can be serviced by that resource.
If there are a lot of INSERTs into a table, this approach will quickly become a severe bottleneck as every single insert requires a new surrogate key value and a lock on that PK_SEQUENCE table to obtain that value.
This problem is solved by allowing/enabling such a resource to serve multiple sessions concurrently. Which is for example what Oracle Sequence objects do within this example I've described.
The bottom line is that the design you describe introduced a bottleneck by create an expensive and serialised resource that can only serve a single session at a time.
You need to re-look at the business requirement - and find another way to solve it than to introduce this type of serialised resource and contention.

Row lock contention error to resolve

hi,
i m facing sever issue with row lock contention error for the statement and causing concurrency and application usage more making database vulnerable
UPDATE RULE_DATA SET RULE_DATA = :B3 , UPDATED_BY = :B2 , UPDATED_DATE = SYSDATE WHERE RULE_DATA_SEQ_ID = :B1
RETURNING PAT_GEN_DETAIL_SEQ_ID INTO :O0
in this query RULE_DATA_SEQ_ID is primary key and and having index too, how can i over come row lock contention error ,
if i try like this will it work
UPDATE RULE_DATA SET RULE_DATA = :B3 , UPDATED_BY = :B2 , UPDATED_DATE = SYSDATE WHERE RULE_DATA_SEQ_ID = :B1
RETURNING PAT_GEN_DETAIL_SEQ_ID INTO :O0
log errors into temp_log (sysdate||:O0 ) REJECT LIMIT UNLIMITED;
commit;
please help me;

select sid, sql_text from v$session s, v$sql q
where sid in (select sid from v$session
where state in ('WAITING')
and wait_class != 'Idle'
and event='enq: TX - row lock contention'
and (q.sql_id = s.sql_id or q.sql_id = s.prev_sql_id));
from the above query if found the sid and sql_text,
actually three procedures been called at once as a batch from java and given auto commit at once for the batch;
and in one of the procedure it is called by multiple times with different seq_id's
what i thought is by logging error can we skip the update statement from locking , this what happening
where v_tariff_detail_seq_id will be 25,26,28,29,30 like records
begin
IF v_tariff_detail_seq_id = 0 THEN
INSERT INTO pat_tariff_details (
tariff_detail_seq_id,
pat_gen_detail_seq_id,
ward_type_id ,
room_type_id ,
days_of_stay ,
requested_amount,
approved_amount,
maximum_allowed_amount,
notes,
added_by,
added_date )
VALUES (
pat_tariff_details_seq.NEXTVAL ,
v_pat_gen_detail_seq_id,
v_ward_type_id ,
v_room_type_id ,
v_days_of_stay ,
v_requested_amount ,
v_approved_amount,
v_maximum_allowed_amount,
v_notes,
v_added_by,
SYSDATE );
ELSE
UPDATE pat_tariff_details SET
room_type_id = v_room_type_id,
days_of_stay = v_days_of_stay,
requested_amount = v_requested_amount,
approved_amount = v_approved_amount,
maximum_allowed_amount = v_maximum_allowed_amount,
notes = v_notes,
updated_by = v_added_by,
updated_date = SYSDATE
WHERE tariff_detail_seq_id = v_tariff_detail_seq_id;
END IF;
end;
version is Oracle Database 10g Release 10.2.0.4.0 - 64bit Production
Edited by: user13134817 on Nov 2, 2012 2:39 AM

Row lock contention problem on Inventory Management

Hi
My client is product based company and have e-Commerce (online Sale Order) application using Oracle database 10.2.0.5 & Web application deployed on WLS. Client have ~ 90 Warehouse country wide and ~ 200 Products (Items). Each product stock for each warehouse is maintained in Inventory Table (INV_BALANCE) which get updated for each order and their sale's products. We are using NO WAIT function to acquire lock on row to update stock balance. Last few months, client business is growing very fast and during Promotional Events (EXPO), they have sales of ~ 75K orders (~ 250K Items) within 2-3 days which start causing row lock contention problem on INV_BALANCE table. We are seeing lots of "Row Lock Wait" and "enq: TX - row lock contention" event which cause ORA-00060: Deadlock detected and we need to eventually clear blocking sessions or everything just choked.
select statistic_name,value from sys.v_$segment_statistics where object_name = 'INV_BALANCE'
STATISTIC_NAME                                                                                                                        VALUE
logical reads                                                                                                                                12423072
buffer busy waits                                                                                                                           3895
db block changes                                                                                                                         3516768
physical reads                                                                                                                               957
physical writes                                                                                                                            12197
row lock waits                                                                                                                             49909
space used                                                                                                                                -52921
Deadlock graph:
                       ---------Blocker(s)-------- ---------Waiter(s)---------
Resource Name          process session holds waits process session holds waits
TX-00880017-00002584       321    1675     X            110    1445           X
TX-00b60008-00000741       110    1445     X            337    2158           X
TX-0148000b-0000009e       337    2158     X            378    1525           X
TX-01d50015-0000006f       378    1525     X            363    1842           X
TX-02290012-00000070       363    1842     X            267    1798           X
TX-024a0026-0000006e       267    1798     X            364    2084           X
TX-020a0004-0000006f       364    2084     X            135    2113           X
TX-01dc001f-00000070       135    2113     X            129    1586           X
session 1675: DID 0001-0141-000001CA    session 1445: DID 0001-006E-00000202
session 1445: DID 0001-006E-00000202    session 2158: DID 0001-0151-0000026B
session 2158: DID 0001-0151-0000026B    session 1525: DID 0001-017A-00000167
session 1525: DID 0001-017A-00000167    session 1842: DID 0001-016B-000002B4
session 1842: DID 0001-016B-000002B4    session 1798: DID 0001-010B-000001F1
Rows waited on:
Session 1445: obj - rowid = 0001AE0E - AAAlK8AAHAAD7rMABY
(dictionary objn - 110094, file - 7, block - 1030860, slot - 88)
Session 2158: obj - rowid = 0001AE0E - AAAlK8AAHAAD7rMACD
(dictionary objn - 110094, file - 7, block - 1030860, slot - 131)
Session 1525: obj - rowid = 0001AE0E - AAAlK8AAHAAD7rOAB2
(dictionary objn - 110094, file - 7, block - 1030862, slot - 118)
Information on the OTHER waiting sessions:
Session 1445:
sid: 1445 ser: 37 audsid: 38316795 user: 69/<none>
            program: JDBC Thin Client
application name: JDBC Thin Client, hash value=2546894660
Current SQL Statement:
SELECT ROWID, NVL(QTY_PEND,0)+NVL(:B3 ,0) FROM INV_BALANCE WHERE WHS_ID = :B2 AND STOCK_ID = :B1 FOR UPDATE OF QTY_PEND WAIT 10
Please help me on following
Q1: How can we reduce the "row lock Contention" on INV_BALANCE, all possible ways & best practices?
Q2: How can we change the design to not have "row lock Contention" at all?
Appreciate your help
Thanks
Amit Garg
www.otnblogs.com

Hi Amit!
I saw you are using FOR UPDATE in your query.
If you want reduce row locks, then you not must use FOR UPDATE.
As you know, FOR UPDATE is locking rows.
Regards
Mahir M. Quluzade

How to find sql causing "enq: TX - row lock contention"

Hi,
In one of our database we keep finding "enq: TX - row lock contention" for 2-3 days. But, then it stopped. The time it happened it blocked other sessions for some long time and it got resolved automatically. Now from ADDM report we got sql queries which waited for this but, we can not find which query from which module was causing the issue. What I should look for that past information. Please help.
Database is 10gR2 on AIX.
Regards,
Gourab

moreajays wrote:
Try executing below query real time
alter session set nls_date_format='dd-mon-yyyy hh24:mi:ss';
SELECT vp.spid,c.inst_id,b.session_id sid,c.serial#,a.object_name,
a.owner object_owner,
Decode(b.locked_mode, 0, 'None',
1, 'Null (NULL)',
2, 'Row-S (SS)',
3, 'Row-X (SX)',
4, 'Share (S)',
5, 'S/Row-X (SSX)',
6, 'Exclusive (X)',
b.locked_mode) locked_mode,
b.oracle_username,
c.program,
d.event,
c.status,
c.last_call_et,
c.sql_address,
e.sql_text, c.logon_time
FROM all_objects a,
gv$locked_object b,
gv$session c,
gv$session_wait d,
gv$sqlarea e,
gv$process vp
WHERE a.object_id = b.object_id
and b.session_id=c.sid
and c.sid=d.sid and c.paddr=vp.addr
and e.address=c.sql_address and lower(d.event) like '%enq%'
ORDER BY 1;
The OP asked for a way of find a historic blocker, not a current blocker.
This query - apart from being one that no-one should want to run on a production system - doesn't say anything about the past, and doesn't identify a blocker.
It reports the sessions that are being blocked, and EVERY table that is currently locked by each session whether or not the table is involved in the current statement.
You're using the gv$ (RAC) views but haven't put in any suitable join predicates on the instance (inst_id) columns; the OP is on 10g so you don't need to join to v$session_wait to pick up the wait information; and the join to v$sqlarea forces a "full tablescan" of the library cache (child cursor derived view) because you're joining on address rather than sql_id.
Regards
Jonathan Lewis

Enq: TX - row lock contention wait event

Hi,
I would like to find which DML query has not given COMMIT or ROLLBACK after the execution. Because one of the development database have more table locks and developer reported that their session was hanging. I referred AWR report also and more timed waits occurred in the enq: TX - row lock contention. I need to trace which DML query has not commit or rollback.
Please help me to solve the issue.
Database version: 11.2.0.1.0
Foreground Wait Events
Event
Waits
%Time -outs
Total Wait Time (s)
Avg wait (ms)
Waits /txn
% DB time
enq: TX - row lock contention
320
0
72,047
225147
0.20
99.53
log file sync
547
0
14
26
0.35
0.02
library cache lock
13
0
11
843
0.01
0.02
SQL*Net break/reset to client
1,080
0
2
1
0.69
0.00
SQL*Net message to client
659,006
0
1
0
421.63
0.00
direct path sync
3
0
1
299
0.00
0.00
SQL*Net more data from client
5,541
0
1
0
3.55
0.00
db file scattered read
554
0
0
1
0.35
0.00
SQL*Net more data to client
14,975
0
0
0
9.58
0.00
db file sequential read
2,817
0
0
0
1.80
0.00
ADR block file read
4
0
0
43
0.00
0.00
enq: CR - block range reuse ckpt
2
0
0
71
0.00
0.00
asynch descriptor resize
38,073
100
0
0
24.36
0.00
latch: shared pool
61
0
0
1
0.04
0.00
control file sequential read
6,900
0
0
0
4.41
0.00
Disk file operations I/O
550
0
0
0
0.35
0.00
cursor: pin S
1
0
0
8
0.00
0.00
direct path write temp
34
0
0
0
0.02
0.00
library cache: mutex X
5
0
0
1
0.00
0.00
latch: In memory undo latch
2
0
0
1
0.00
0.00
buffer busy waits
14
0
0
0
0.01
0.00
SQL*Net message from client
658,990
0
294,847
447
421.62
jobq slave wait
669
99
333
497
0.43
PL/SQL lock timer
1
100
1
998
0.00

Oracle does not and cannot tell you from historical views (e.g. AWR) which DMLs have not COMMITed or ROLLBACKed. A Transaction ends with a COMMIT or ROLLBACK. The transaction could have a million (or more) DML statements with a million (or more) SELECT statements between the first DML and the COMMIT / ROLLBACK.
Even identifying such DMLs in real time is close to impossible. Because the session holding the lock may have issued a dozen or a million subsequent SQL statements while other sessions are waiting for the lock. You can only identify the session that is the lock holder (the BLOCKING_SESSION in V$SESSION).
If you have tracing enabled for all sessions, then you could review the trace file for the BLOCKING_SESSION to identify the DML(s) the session has executed.
Hemant K Chitale

Enq : TX row lock contention with no lock holder !!

Hi, all.
The database is 2 node RAC (oracle 11.2.0.3 ) on a unix machine.
Today morning, I found the instances sufferred "enq : TX row lock contention" YESTERDAY.
I issued the following query,
but block_session, blocking_session_serial# and blocking_inst_id column are null.
select a.instance_number,a.sample_time,a.session_id,a.session_serial#,a.sql_id,
a.event,a.wait_class, a.p1, a.p2, a.p3,a.current_obj#,
a.blocking_session,a.blocking_session_serial#,a.blocking_inst_id
from dba_hist_active_sess_history a
where a.instance_number=1
and a.event='enq: TX - row lock contention'
order by a.instance_number,sample_id
Any advice will be greately appreciated.
Thanks in advance.
Best Regards.

In addition to run the script , also download and run Snapper script from Tanel Poder which would give even more detail for the session .
http://files.e2sn.com/scripts/snapper.sql
HTH
Aman....

Enq: TX - row lock contention problem

Hi ,
Db version 10.2.0.4
os solaris.
i have upgraded my database from 9.2.0.4 to 10.2.0.4 by using exp/imp as my database is small.
I have created new instance of 10g and changed parameter values as 9i(as required). then imported from 9i to 10g instance.
After importing in 10g instance we are face application wide performance problem..the response time of the applicatoin was very slow...
i have taken awr report of various times and have seeen
SELECT puid,ptimestamp FROM PPOM_OBJECT WHERE puid IN (:1) FOR UPDATE
this query is causing the problem..enq: TX - row lock contention
Cache Sizes
~~~~~~~~~~~                       Begin        End
               Buffer Cache:       756M       756M Std Block Size:         8K
           Shared Pool Size:       252M       252M      Log Buffer:     1,264K
Load Profile
~~~~~~~~~~~~                            Per Second       Per Transaction
                  Redo size:              2,501.54              3,029.25
              Logical reads:              2,067.79              2,504.00
              Block changes:                 17.99                 21.78
             Physical reads:                  0.02                  0.03
            Physical writes:                  0.41                  0.50
                 User calls:                140.74                170.44
                     Parses:                139.55                168.99
                Hard parses:                  0.01                  0.01
                      Sorts:                 10.65                 12.89
                     Logons:                  0.32                  0.38
                   Executes:                139.76                169.24
               Transactions:                  0.83
% Blocks changed per Read:    0.87    Recursive Call %:    17.60
Rollback per transaction %:    0.00       Rows per Sort:    16.86
Instance Efficiency Percentages (Target 100%)
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
            Buffer Nowait %: 100.00       Redo NoWait %: 100.00
            Buffer Hit   %: 100.00    In-memory Sort %: 100.00
            Library Hit   %: 100.03        Soft Parse %: 100.00
         Execute to Parse %:    0.15         Latch Hit %:   99.89
Parse CPU to Parse Elapsd %:   93.19     % Non-Parse CPU:   94.94
Shared Pool Statistics        Begin    End
             Memory Usage %:   86.73   86.55
    % SQL with executions>1:   90.99   95.33
% Memory for SQL w/exec>1:   79.15   90.58
Top 5 Timed Events                                         Avg %Total
~~~~~~~~~~~~~~~~~~                                        wait   Call
Event                                 Waits    Time (s)   (ms)   Time Wait Class
CPU time                                            397          86.3
enq: TX - row lock contention           508          59    115   12.7 Applicatio
log file sync                         2,991           5      2    1.1     Commit
log file parallel write               3,238           5      2    1.1 System I/O
SQL*Net more data to client          59,871           4      0    1.0    Network
^LTime Model Statistics              DB/Inst: WGMUGPR2/wgmugpr2 Snaps: 706-707
-> Total time in database user-calls (DB Time): 460.5s
-> Statistics including the word "background" measure background process
   time, and so do not contribute to the DB time statistic
-> Ordered by % or DB time desc, Statistic name
                                                                   Avg
                                             %Time Total Wait    wait     Waits
Event                                 Waits -outs    Time (s)    (ms)      /txn
enq: TX - row lock contentio            508     .0          59     115       0.2
log file sync                         2,991     .0           5       2       1.0
log file parallel write               3,238     .0           5       2       1.1
SQL*Net more data to client          59,871     .0           4       0      20.1
control file parallel write           1,201     .0           1       1       0.4
SQL*Net more data from clien          3,393     .0           1       0       1.1
SQL*Net message to client           509,864     .0           1       0     170.9
os thread startup                         3     .0           1     196       0.0
db file parallel write                  845     .0           1       1       0.3
-> % Total DB Time is the Elapsed Time of the SQL statement divided
   into the Total Database Time multiplied by 100
Elapsed      CPU                  Elap per % Total
Time (s)   Time (s) Executions   Exec (s) DB Time    SQL Id
        59          1        1,377        0.0    12.9 bwnt27fp0z3gm
Module: syncdizio_op@snstr09 (TNS V1-V3)
SELECT puid,ptimestamp FROM PPOM_OBJECT WHERE puid IN (:1) FOR UPDATE
        41         41          459        0.1     8.9 8cdswsp7cva2h
Module: syncdizio_op@snstr09 (TNS V1-V3)
select rpad(argument_name, 32, ' ') || in_out || ' ' || nvl(type_subname, data_t
ype) info from user_arguments where package_name IS NULL and object_name = uppe
r(:1) and argument_name is not null order by object_name, position
        39         38        7,457        0.0     8.4 271hn6sgra2d8
Module: syncdizio_op@snstr09 (TNS V1-V3)
SELECT DISTINCT t_0.puid FROM PIMANTYPE t_0 WHERE (UPPER(t_0.ptype_name) = UPPER
(:1))
        23         22          459        0.0     4.9 g92t08k78tgrw
Module: syncdizio_op@snstr09 (TNS V1-V3)
SELECT PIMANTYPE.puid, ptimestamp, ppid, rowning_siteu, rowning_sitec, pis_froze
n, ptype_class, ptype_name FROM PPOM_OBJECT, PIMANTYPE WHERE PPOM_OBJECT.puid =
(PIMANTYPE.puid)
        22         22      158,004        0.0     4.9 chqpmv9c05ghq
Module: syncdizio_op@snstr09 (TNS V1-V3)
SELECT puid,ptimestamp FROM PPOM_OBJECT WHERE puid = :1
        17         17        2,294        0.0     3.7 3n5trh11n1x8w
Module: syncdizio_op@snstr09 (TNS V1-V3)
SELECT PTYPECANNEDMETHOD.puid, ptimestamp, ppid, rowning_siteu, rowning_sitec, p
is_frozen, pobject_desc, psecure_bits,VLA_344_5, pmethod_name, pmsg_name, ptype_
name, pexec_seq, paction_type FROM PPOM_OBJECT,PBUSINESSRULE, PTYPECANNEDMETHOD
WHERE PTYPECANNEDMETHOD.puid IN (:1,:2,:3,:4,:5,:6,:7,:8,:9,:10,:11,:12,:13,:14,in 9i there is a parameter ENQUEUE_RESOURCES but in 10g relese 2 its got obsoleted....
am new to performace tunning please advice me....!
Regards
Vamshi

The CBO has changed substantially between 9.2.x and 10.2.x. Pl see MOS Doc 754931.1 (Cost Based Optimizer - Common Misconceptions and Issues - 10g and Above). Pl verify that statistics have been gathered and are current - pl see MOS Doc 605439.1 (Master Note: Recommendations for Gathering Optimizer Statistics on 10g).
Looking at your output, it seems to me that the database is entirely CPU-bound. 86.3% of time is spent on CPU. The last 5 SQL statements in the output, all of the elapsed time is spent on CPU.
Pl post your init.ora parameters, along with your hardware specs. This question might be more appropriate in the "Database - General" forum.
HTH
Srini

Enq: TX - row lock contention in AWR reports

Dears,
One of my friends asked me to give him a help on analyzing a performance problem they are experimenting from time to time. First of all I am sorry to tell you that he didn’t gave me a lot of information. I will share with you all what I have been sent and would like to have your precious advice according to the available information.
It is a third party software installed on oracle data base 10.2.0.4.0. He said that from time to time the application hangs. He sends me an AWR reports supplied by the local DBA. Unfortunately, the local DBA send only the AWR information he thinks are most important to be looked at (he did not include the load profile and the instance efficiency Percentages part in this AWR for example).
Here below is the available information I can share with you
                                                                         Snap time                                       sessions        cursors/session
Begin Snap        09-mars-11 08:00:03              31                     6.5
End Snap          09-mars-11 08:39:49              41                     9.8
Elapsed           39.77 (mins)
DB Time           536.65(mins)
Top 5 Timed Events
Event                          Waits   Time(s)    Avg Wait(ms)    % Total Call Time     Wait Class
enq: TX - row lock contention 8,468    25,344       2,993            78.7             Application
read by other session          714,628   4,604         6               14.3             User I/O
db file sequential read        323,264 1,977         6               6.1              User I/O
CPU time                                 171                          .5
db file scattered read          1,885   49           26               .2               User I/OThe AWR reports presents also the following SQL statement as the top SQL of its ‘’SQL ordered by Elapsed Time’’ part
UPDATE xxxx.table1
   SET col1 = :1,
       col2 = :2,
       col3 = :3,
       col4 = :4,
WHERE ID = :13
AND colx = :14;And the following sql at its “SQL ordered by Reads’ part
SELECT t1.*
FROM xxxx.table1 t1
LEFT OUTER JOIN xxxx.table2 t2
       ON t1.id = t2.id
LEFT OUTER JOIN xxxx.table3 t3
       ON t1.id = t3.id
LEFT OUTER JOIN xxxx.table4 t4
       ON t1.id = t4.id
WHERE t1.col1 = :1
AND   t1.col2 IN (:2,:3, :4);And finally in the Segments by Row Lock Waits part of the AWR I have this:
Owner      tablespace name    object name   object type   row lock waits   %of capture
xxxx          xxxx          table1         TABLE          54       100    There are no bitmap indexes on this OLTP data base. There are no unindexed foreign keys and it seems that there are no selects done over a dblink.
I am waiting to have the table table1 script and its indexes
Given those information I think that the locking problem is due to this update on table table1 which is not followed immediately by a commit or a rollback. But, instead, several selects that might be taking a long time are done before reaching the commit that ends the lock on the table table1
What do you think about the possible reason of this lock?
Thanks in advance
Mohamed Houri

Dears,
I did get the suspected query and asked for its several explain plans thanks to the dbms_xplan.display_awr. The most important thing to point out is that the last where clause of this query seems to be dynamically filled-up
SELECT t1.*
FROM xxxx.table1 t1
LEFT OUTER JOIN xxxx.table2 t2
       ON t1.id = t2.id
LEFT OUTER JOIN xxxx.table3 t3
       ON t1.id = t3.id
LEFT OUTER JOIN xxxx.table4 t4
       ON t1.id = t4.id
WHERE t1.col1 = :1
AND   t1.col2 in (:2 , :3 , :4 , :5 , :6 , :7 , :8 )
| Id | Operation                      | Name                    | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT               |                         |       |       |    14 (100)|          |
|   1 | NESTED LOOPS OUTER            |                         |     1 |   280 |    14   (0)| 00:00:01 |
|   2 |   NESTED LOOPS OUTER           |                         |     1 |   226 |     9   (0)| 00:00:01 |
|   3 |    NESTED LOOPS OUTER          |                         |     1 |   216 |     6   (0)| 00:00:01 |
|   4 |     TABLE ACCESS BY INDEX ROWID| TABLE1                  |     1 |   141 |     4   (0)| 00:00:01 |
|   5 |      INDEX RANGE SCAN          | SYS_C0010893            |     1 |       |     3   (0)| 00:00:01 |
|   6 |     TABLE ACCESS BY INDEX ROWID| TABLE2                  |     1 |    75 |     2   (0)| 00:00:01 |
|   7 |      INDEX UNIQUE SCAN         | SYS_C0010774            |     1 |       |     1   (0)| 00:00:01 |
|   8 |    INDEX RANGE SCAN            | SYS_C0010896            |     3 |    30 |     3   (0)| 00:00:01 |
|   9 |   TABLE ACCESS BY INDEX ROWID | TABLE3                  |    11 |   594 |     5   (0)| 00:00:01 |
| 10 |    INDEX RANGE SCAN            | SYS_C0010910            |    11 |       |     3   (0)| 00:00:01 |
SELECT t1.*
FROM xxxx.table1 t1
LEFT OUTER JOIN xxxx.table2 t2
       ON t1.id = t2.id
LEFT OUTER JOIN xxxx.table3 t3
       ON t1.id = t3.id
LEFT OUTER JOIN xxxx.table4 t4
       ON t1.id = t4.id
WHERE t1.col1 = :1
AND   t1.col2 in (:2 , :3 , :4 , :5 , :6 , :7 , :8 , :9 , :10 , :11 , :12 , :13 , :14 , :15 , :16 ,
:17 , :18 , :19 , :20 , :21 , :22 , :23 , :24 , :25 , :26 , :27 , :28 , :29 , :30 , :31 , :32 ,
:33 , :34 , :35 , :36 , :37 , :38 , :39 , :40 , :41 , :42 , :43 , :44 , :45 , :46 , :47 , :48 ,
:251 , :252 , :253 , :254 , :255 , :256 , :257 ) ;
| Id | Operation                       | Name                    | Rows | Bytes | Cost (%CPU)| Time     |
|   0 | SELECT STATEMENT                |                         |       |       | 5943 (100)|          |
|   1 | NESTED LOOPS OUTER             |                         | 9210 | 2536K| 5943   (1)| 00:01:12 |
|   2 |   NESTED LOOPS OUTER            |                         |   885 |   195K| 1784   (0)| 00:00:22 |
|   3 |    NESTED LOOPS OUTER           |                         |   255 | 55080 | 1019   (0)| 00:00:13 |
|   4 |     INLIST ITERATOR             |                         |       |       |            |          |
|   5 |      TABLE ACCESS BY INDEX ROWID| TABLE1                  |   255 | 35955 |   509   (0)| 00:00:07 |
|   6 |       INDEX UNIQUE SCAN         | SYS_C0010893            |   255 |       |   258   (0)| 00:00:04 |
|   7 |     TABLE ACCESS BY INDEX ROWID | TABLE2                  |     1 |    75 |     2   (0)| 00:00:01 |
|   8 |      INDEX UNIQUE SCAN          | SYS_C0010774            |     1 |       |     1   (0)| 00:00:01 |
|   9 |    INDEX RANGE SCAN             | SYS_C0010896            |     3 |    30 |     3   (0)| 00:00:01 |
| 10 |   TABLE ACCESS BY INDEX ROWID   | TABLE3                  |    10 |   560 |     5   (0)| 00:00:01 |
| 11 |    INDEX RANGE SCAN             | FK_TABLE3               |    10 |       |     3   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------------------   Suddenly there is an INLIST ITERATOR that pops up and which seems to be started 255 times and the ‘quick’ query which in normal situation (small in list) executes in less than 1 second starts now taking more than 1 minute to complete.
As far as it is a third party software, they can’t change the query.
Do you have any idea on how to solve this problem?
Here below are the optimizer parameters
SQL> show parameter optimizer
NAME                                 TYPE        VALUE
optimizer_dynamic_sampling           integer     2
optimizer_features_enable            string      10.2.0.4
optimizer_index_caching              integer     0
optimizer_index_cost_adj             integer     100
optimizer_mode                       string      ALL_ROWS
optimizer_secure_view_merging        boolean     TRUEThanks in advance
Mohamed Houri

Enq: TX - row lock contention in forms 10g sequency number generation

Iam Getting the Deadlock issue in oracle formdeveloper 10g database is 11g Acutually in our small Hospital organization using different forms generating entrying labrequest form finally save time
one sequency number will generated i have give procedure below every save criteria form using below procedure some time iam getting lock iam using blocksession query i have find out some
OSUSER
MACHINE
TERMINAL
PROGRAM
SQL_ID
LOGON_TIME
BLOCKING_SESSION_STATUS
BLOCKING_SESSION
EVENT
user423
UMCCDOM\LEVEL4-MICU
LEVEL4-MICU
PrjMcr.EXE
0ccngw7dfkmgb
23/09/2013 11:34:41 AM
VALID
277
enq: TX - row lock contention
SYSTEM
WORKGROUP\PRIAPPSVR
PRIAPPSVR
frmweb.exe
0ccngw7dfkmgb
23/09/2013 11:32:50 AM
VALID
186
enq: TX - row lock contention
SYSTEM
WORKGROUP\PRIAPPSVR
PRIAPPSVR
frmweb.exe
0ccngw7dfkmgb
22/09/2013 2:49:47 PM
VALID
277
enq: TX - row lock contention
SYSTEM
WORKGROUP\PRIAPPSVR
PRIAPPSVR
frmweb.exe
0ccngw7dfkmgb
23/09/2013 7:00:22 AM
VALID
186
enq: TX - row lock contention
user290
UMCCDOM\LEVEL2-N
LEVEL2-N
PrjMcr.EXE
0ccngw7dfkmgb
23/09/2013 10:28:06 AM
VALID
277
enq: TX - row lock contention
lock are happen after open the code i have find out used FOR UPDATE in procedure please tell me any alternative for this every labrequest form saving time using this procedure for generating prefix sequence number multiple user using with different systems
PROCEDURE   Gsp_GenSeqNum (I_SvPrefixCd IN VARCHAR2,I_SvUserName IN VARCHAR2,
                          O_SvSeqNum OUT VARCHAR2) IS
--This Procedure generates the sequence number
--by retrieving the prefix based on the code
--supllied to the procedure.
CURSOR crSeqGenerator IS
         SELECT Gsn_prefix_last_num, Gsn_prefix_year
            FROM G_SEQUENCE_NUMBER
         WHERE Gsn_prefix_Cd = I_SvPrefixCd
               AND Gsn_prefix_year = TO_CHAR(SYSDATE,'YYYY')
FOR UPDATE OF Gsn_prefix_last_num;
udSeqNum        G_SEQUENCE_NUMBER.Gsn_Prefix_last_num%TYPE;
udNextSeqNum    G_SEQUENCE_NUMBER.Gsn_Prefix_last_num%TYPE;
udYear          G_SEQUENCE_NUMBER.Gsn_Prefix_year%TYPE;
udPrefix        G_SEQUENCE_PREFIX.Gsp_Prefix_Value%TYPE;
BEGIN
SELECT Gsp_Prefix_Value
INTO udPrefix
FROM G_SEQUENCE_PREFIX
WHERE Gsp_Prefix_Cd = I_SvPrefixCd;
OPEN crSeqGenerator;
FETCH crSeqGenerator
   INTO udSeqNum,
        udYear;
IF crSeqGenerator%FOUND THEN
     udNextSeqNum :=udSeqNum + 1;
     O_SvSeqNum     := udPrefix||'/'||TO_CHAR(SYSDATE,'YY')
                               ||'/'||LPAD(TO_CHAR(udNextSeqNum),6,'0');
ELSE
INSERT INTO G_SEQUENCE_NUMBER VALUES(I_SvPrefixCd,TO_CHAR(SYSDATE,'YYYY'),0,I_SvUserName,SYSDATE);
     udSeqNum      :=0;
     udNextSeqNum :=udSeqNum + 1;
     O_SvSeqNum:=UdPrefix||'/'||TO_CHAR(SYSDATE,'YY')
                         ||'/'||LPAD(TO_CHAR(udNextSeqNum),6,'0');
END IF;
UPDATE G_SEQUENCE_NUMBER
     SET Gsn_Prefix_last_num=udNextSeqNum
   WHERE Gsn_Prefix_Cd = I_SvPrefixCd
     AND Gsn_Prefix_year=TO_CHAR(SYSDATE,'YYYY');
CLOSE crSeqGenerator;
END Gsp_GenSeqNum;
Thanks
subbu

This application is inbuit with some modules VB (cath ,cardio)and oracle forms for required sequence number generation different time used this procedure whereever required the sequence Prefix generation.If i replace the procedure sequene to oracle standard sequency if the user cannot save the form unnessary sequency generated order is missing from sequence.

V$system_event, timeouts and row lock contention

Hello everyone,
What is the meaning of the total_timeouts column in the v$system_event view if it is related to the event "enq: TX - row lock contention"?
How can we have a timeout since "query timeout" is a non existent concept on Oracle?
Maybe I am wrong.
Regards.
Carl

Hello everyone,
What is the meaning of the total_timeouts column in
the v$system_event view if it is related to the event
"enq: TX - row lock contention"?
How can we have a timeout since "query timeout" is a
non existent concept on Oracle?
Maybe I am wrong.
Regards.
CarlThe value for timeouts, in this case, indicates the number of times one of the sessions had to wait a full 3 second time slice while waiting for a second session to either commit or roll back, in anticipation of a potential primary key violation. If the second session commits, the first session will receive an error indicating a primary key violation.
Test setup:
In session 2:
CREATE TABLE T1 (C1 VARCHAR2(20) PRIMARY KEY);
INSERT INTO T1 VALUES ('ORACLE');
In session 1:
INSERT INTO T1 VALUES ('ORACLE');
After executing tha above, allow 60 seconds to elapse after the insert in session 1, and then check the delta values in either V$SYSTEM_EVENT or V$SESSION_EVENT:
20 waits on ENQ: TX - ROW LOCK CONTENTION, 19 timeouts, 59.99 seconds, with an average wait of 2.9995 seconds.
Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

Tuning row lock contention wait events

Hello everyone,
Working on 10g/windows
Top 5 events
EVENT TOTAL_WAITS TIME_WAITED AVG_MS PERCENT
CPU 9462339 48
enq: TX - row lock contention 12531 3660728 2921.34 18
control file parallel write 1300731 3088079 23.74 16
log file parallel write 1510503 1264080 8.37 6
log file sync 1072553 968007 9.03 5
Distribution of row lock wait during the last 4 days in the database server
END_INTERVAL_TIME TOTAL_WAITS TIME_WAITED_MICRO AVG_WAIT_MS
2008-04-01 16:00:58 909 2721008230 2993.41
2008-04-01 15:00:27 50 149941140 2998.82
2008-03-31 12:00:42 193 575595397 2982.36
2008-03-29 23:00:13 172 513058700 2982.9
2008-03-29 22:00:37 164 483940046 2950.85
2008-03-27 22:00:35 565 1667120838 2950.66
2008-03-26 18:00:59 348 1042918982 2996.89
My analysis:
It's obvious that the row lock contention wait time is huge, and this direct me to find out SQL stmt, causing this.
all the SQL statement was SELECT ....... FOR UPDATE stmt.
I was also able to find out locked tables.
My tuning idea:
1. I'm thinking to reorganize hot tables as well as their indexes, but by instinct it seems to not give so much value to avoid the huge row lock wait time.
2. I'm also seeing if I can reduce the number of rows per block, by increasing PCTFREE and diminishing PCTUSED, so the contention will spread over many blocks instead of one heavy block.
Question
As SQL stmt related to those locked tables are select ... for update, how could I tune this kind of stmt?
Does someone have other idea to come up with this row lock contention?
Tanks for your effort and help

Taking another look at your suggested function based index, it depends on the data type of the DEV.POS_FOLIO_ID.POS_FOLIO_ID column. If the column is defined as a number, and it is a primary key, there will already be a usable index on that column.
Yesterday, I wrote this: "Once I understood why or how the sessions were trying to insert duplicate primary key values, I would try to determine why the average number of seconds for the wait event is almost 3 seconds (maybe a timeout)."
After fixing the formatting of the top 5 wait events (total duration unknown):
EVENT                        TOTAL_WAITS TIME_WAITED   AVG_MS PERCENT
CPU                                         94,623.39             48
enq: TX - row lock contention     12,531    36,607.28 2921.34    18
control file parallel write    1,300,731    30,880.79    23.74    16
log file parallel write        1,510,503    12,640.80     8.37     6
log file sync                  1,072,553     9,680.07     9.03     512,531 * 3 second time out = 37,593 seconds = 10.44 hours.
What if the reason for the 3 second average wait time is due to a timeout. I performed a little experiment... I changed a row in a test table and then made a pot of coffee.
In session 1:
CREATE TABLE T1 (
C1 NUMBER(10),
C2 NUMBER(10),
PRIMARY KEY (C1));
INSERT INTO T1
SELECT
ROWNUM,
ROWNUM*10
FROM
DUAL
CONNECT BY
LEVEL<=1000000;
COMMIT;I now have a test table with 1,000,000 rows. I start monitoring the changes in the wait events roughly every 60 seconds, and V$SESSION_WAIT and V$LOCK roughly 4 times per second.
Back in session 1:
UPDATE
T1
SET
C1=-C1
WHERE
C1<=100;I have now modified the first 100 rows that were inserted into the table, time to make the pot of coffee.
In session 2, I try to insert a row with a primary key value of -10:
INSERT INTO T1 VALUES (
-10,
10);Session 2 hangs.
If I take the third 60 second snap of the system wide wait events as the zero point, and the 11th snap as the end point. There were 149 waits on ENQ: TX - ROW LOCK CONTENTION, 148 time outs, 446.62 seconds of total time in the wait event, with an average wait time of 2.997450 seconds.
Rolling down to the session level wait events, SID 208 (my session 2) had 149 waits on ENQ: TX - ROW LOCK CONTENTION, for a total time of 446.61 seconds with an average wait time of 2.997383 seconds. All of the 149 waits and the wait time was in this one session that was locked up for the full duration of this time period because session 1 was making a pot of coffee.
Rolling down to V$SESSION_WAIT (sampled roughly 4 times per second): At the start of the third time interval, SID 208 has been in the ENQ: TX - ROW LOCK CONTENTION wait event for 39 seconds and is actively waiting trying to execute SQL with a hash value of 1001532423, the wait object is -1, wait file is 0, wait block is 0, wait row is 0, P1 is 1415053316, P2 is 196646, P3 is 4754.
At the end of the 11th time interval: , SID 208 has been in the ENQ: TX - ROW LOCK CONTENTION wait event for 483 seconds and is actively waiting trying to execute SQL with a hash value of 1001532423, the wait object is -1, wait file is 0, wait block is 0, wait row is 0, P1 is 1415053316, P2 is 196646, P3 is 4754.
Rolling down to V$LOCK (sampled roughly 4 times per second): I see that SID 214 (session 1) is blocking SID 208 (session 2). SID 214 has a TX lock in mode 6 with ID1 of 196646 and ID2 of 4754. SID 208 is requesting a TX lock in mode 4 with ID1 of 196646 and ID2 of 4754.
So, it seems that I need a faster coffee pot rather than an additional index on my table. It could be that the above process would have found that the application associated with SID 214 was abandoned or crashed and for some reason the lock was not released for a long period of time, a little less than 10.44 hours in your case.
Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc.

TX - row lock contention in SELECT query without update clause

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