UnitOfWork doesn't release pessimistic row lock???

I have an application that polls a DB table for new "submissions", then forwards them to another server to handle them asynchronously. When the asynchronous response comes back, my application verifies that all response have been received from the server, then sends a combined response. My problem is that the asynchronous response listener threads appear to deadlock when pessimistically locking the submission row, even though the transaction that locked it has been closed for ~1s.
Some psuedocode may help explain the problem. This is my DB polling thread
while( true ) {
Submission s = getNextSubmissionAndLockPessimistically();
if( s == null )
return null;
Server s2 = getServerCapableOfRunning( s );
if( s2 != null )
return s2;
uow.revertAndResume();
I am worried that in the instance that a server capable of running the submission could not be found, or is too full, the UnitOfWork#revertAndResume method does not release the row lock for the submission. Are there any scenarios where this can occur?
On another note, I occasionally receive "Query sent to unactivated UnitOfWork" exceptions during the uow.revertAndResume() call. My code only uses the first UnitOfWork returned by EntityManager#getUnitOfWork(). Could the two be related? Does anyone have any ideas on how to fix this exception?
Thanks,
Dan

Thank you for the detailed description of how the locks are released; I mistakenly assumed the revertObject/revertAndResume would release them. I will refactor my code to create EntityManager/UnitOfWork instances in loop and release/close them instead of reverting.
As for the "unactivated UnitOfWork" exception, here is one of my stack traces:
Exception [TOPLINK-6027] (Oracle TopLink Essentials - 2.0 (Build b41-beta2 (03/30/2007))): oracle.toplink.essentials.exceptions.QueryException
Exception Description: Query sent to a unactivated UnitOfWork.
Query: ReadAllQuery(my.package.ServerLimits)
at oracle.toplink.essentials.exceptions.QueryException.querySentToInactiveUnitOfWork(QueryException.java:893)
at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2217)
at oracle.toplink.essentials.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:937)
at oracle.toplink.essentials.internal.indirection.QueryBasedValueHolder.instantiate(QueryBasedValueHolder.java:86)
at oracle.toplink.essentials.internal.indirection.QueryBasedValueHolder.instantiate(QueryBasedValueHolder.java:76)
at oracle.toplink.essentials.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:90)
at oracle.toplink.essentials.indirection.IndirectList.buildDelegate(IndirectList.java:193)
at oracle.toplink.essentials.indirection.IndirectList.getDelegate(IndirectList.java:315)
at oracle.toplink.essentials.indirection.IndirectList.size(IndirectList.java:640)
at oracle.toplink.essentials.internal.queryframework.CollectionContainerPolicy.sizeFor(CollectionContainerPolicy.java:184)
at oracle.toplink.essentials.internal.indirection.TransparentIndirectionPolicy.getRealAttributeValueFromObject(TransparentIndirectionPolicy.java:252)
at oracle.toplink.essentials.mappings.ForeignReferenceMapping.getRealAttributeValueFromObject(ForeignReferenceMapping.java:370)
at oracle.toplink.essentials.mappings.CollectionMapping.getRealAttributeValueFromObject(CollectionMapping.java:559)
at oracle.toplink.essentials.mappings.CollectionMapping.getRealCollectionAttributeValueFromObject(CollectionMapping.java:574)
at oracle.toplink.essentials.mappings.CollectionMapping.mergeIntoObject(CollectionMapping.java:734)
at oracle.toplink.essentials.internal.descriptors.ObjectBuilder.mergeIntoObject(ObjectBuilder.java:2114)
at oracle.toplink.essentials.internal.descriptors.ObjectBuilder.mergeIntoObject(ObjectBuilder.java:2096)
at oracle.toplink.essentials.internal.sessions.MergeManager.mergeChangesOfOriginalIntoWorkingCopy(MergeManager.java:450)
at oracle.toplink.essentials.internal.sessions.MergeManager.mergeChanges(MergeManager.java:251)
at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.revertAndResume(UnitOfWorkImpl.java:3527)
at my.package.DbInterface.getNextSubmissionAndServer(DbInterface.java:460)
at my.package.PollingThread.waitForNextSubmission(PollingThread.java:175)
at my.package.PollingThread.run(PollingThread.java:122)
This particular error could be related to the DB lock obtained on the Server object, which has a One-To-Many relationship to the ServerLimits.
However, there is another exception that I am worried about:
Exception [TOPLINK-6027] (Oracle TopLink Essentials - 2.0 (Build b41-beta2 (03/30/2007))): oracle.toplink.essentials.exceptions.QueryException
Exception Description: Query sent to a unactivated UnitOfWork.
Query: ReadAllQuery(my.package.Submission)
at oracle.toplink.essentials.exceptions.QueryException.querySentToInactiveUnitOfWork(QueryException.java:893)
at oracle.toplink.essentials.internal.sessions.UnitOfWorkImpl.internalExecuteQuery(UnitOfWorkImpl.java:2217)
at oracle.toplink.essentials.internal.sessions.AbstractSession.executeQuery(AbstractSession.java:937)
at oracle.toplink.essentials.internal.indirection.QueryBasedValueHolder.instantiate(QueryBasedValueHolder.java:86)
at oracle.toplink.essentials.internal.indirection.QueryBasedValueHolder.instantiate(QueryBasedValueHolder.java:76)
at oracle.toplink.essentials.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:90)
at oracle.toplink.essentials.internal.indirection.UnitOfWorkValueHolder.instantiateImpl(UnitOfWorkValueHolder.java:160)
at oracle.toplink.essentials.internal.indirection.UnitOfWorkValueHolder.instantiate(UnitOfWorkValueHolder.java:232)
at oracle.toplink.essentials.internal.indirection.DatabaseValueHolder.getValue(DatabaseValueHolder.java:90)
at oracle.toplink.essentials.indirection.IndirectList.buildDelegate(IndirectList.java:193)
at oracle.toplink.essentials.indirection.IndirectList.getDelegate(IndirectList.java:315)
at oracle.toplink.essentials.indirection.IndirectList.add(IndirectList.java:140)
at my.package.db.Transaction.addSubmission(Transaction.java:422)
at my.package.DbInterface.createNewSubmission(DbInterface.java:284)
at my.package.EngineInterface.executeObjectFn(EngineInterface.java:446)
at my.package.EngineInterface.executeBooleanFn(EngineInterface.java:412)
at my.package.EngineInterface.search(EngineInterface.java:252)
at my.package.mdb.RequestListenerBean.onMessage(RequestListenerBean.java:457)
at sun.reflect.GeneratedMethodAccessor21.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:585)
at com.evermind.server.ejb.interceptor.joinpoint.EJBJoinPointImpl.invoke(EJBJoinPointImpl.java:35)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.DMSInterceptor.invoke(DMSInterceptor.java:52)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.interceptor.system.SetContextActionInterceptor.invoke(SetContextActionInterceptor.java:44)
at com.evermind.server.ejb.interceptor.InvocationContextImpl.proceed(InvocationContextImpl.java:119)
at com.evermind.server.ejb.InvocationContextPool.invoke(InvocationContextPool.java:55)
at oracle.j2ee.connector.messageinflow.MessageEndpointImpl.OC4J_invokeMethod(MessageEndpointImpl.java:297)
at RequestListenerBean_EndPointProxy_44242m8.onMessage(Unknown Source)
at oracle.j2ee.ra.jms.generic.WorkConsumer.run(WorkConsumer.java:268)
at oracle.j2ee.connector.work.WorkWrapper.runTargetWork(WorkWrapper.java:242)
at oracle.j2ee.connector.work.WorkWrapper.doWork(WorkWrapper.java:215)
at oracle.j2ee.connector.work.WorkWrapper.run(WorkWrapper.java:190)
at EDU.oswego.cs.dl.util.concurrent.PooledExecutor$Worker.run(PooledExecutor.java:819)
at java.lang.Thread.run(Thread.java:595)
The code that caused this error is about as simple as it can get:
EntityManager em = (EntityManager) emf.createEntityManager();
UnitOfWork uow = em.getUnitOfWork();
try
// locate owning transaction and the RECEIVED_FROM_ESB type
Transaction tx = locate( Transaction.class, em, uow, txId );
ServerFunction fn = locate( ServerFunction.class, em, uow, fnId );
TrackingType trackingType = locate( TrackingType.class, em, uow, TrackingType.RECEIVED_FROM_ESB );
// create submission
Submission submission = new Submission();
submission.setPriority( priority );
submission.setRequestId( requestId );
submission.setNistId( nistId );
submission.setFunction( fn );
// create RECEIVED_FROM_ESB tracking status
TrackingStatus status = new TrackingStatus();
status.setTrackingType( trackingType );
status.setStatusTime( new Timestamp( System.currentTimeMillis() ) );
submission.addTrackingStatus( status );
tx.addSubmission( submission );
em.persist( submission );
uow.commit();
em.close();
return submission.getId();
finally
if( uow.isActive() )
uow.release();
if( em.isOpen() )
em.close();
There is a One-To-Many mapping from Transaction to Submission, and a One-To-Many mapping from Submission to TrackingStatus.
If anyone can offer any insight into what I'm doing wrong, I'd appreciate it!
Thanks,
Dan

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                       ---------Blocker(s)-------- ---------Waiter(s)---------
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TX-003a0011-000003d0        44       548     X               30        542             X
TM-0000be63-00000000       30       542     SX              44        548     SX    SSX
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session 542: DID 0001-001E-00000050     session 548: DID 0001-002C-000002D9
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O/S info: user: cascade, term: unknown, ospid: 1234, machine:
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application name: JDBC Thin Client, hash value=2546894660
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at oracle.jdbc.driver.DatabaseError.throwSqlException(DatabaseError.java:287)
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at oracle.jdbc.driver.OracleStatement.execute_maybe_describe(OracleStatement.java:1029)
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at oracle.jdbc.driver.OraclePreparedStatement.executeInternal(OraclePreparedStatement.java:3001)
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I would check the network pieces as suggested in our internal emails. If the connection is dropping somewhere on your network, the lock would never be released.
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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.

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

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

Front Row Locking up

Hello Front Row Support forum!
I recently upgraded to Leopard (Much <3 for the new version of OS X) and I've actually started using Front Row. I really like the new look and it fits into my lifestyle more now to use it.
Unfortunately though, Front Row has been periodically locking up when I listen to music. It becomes completely non-responsive and I can't even force my way out of it. I've actually had to resort to turning my laptop completely off
Any suggestions, fixes, or magic tricks to help me?

I have the same problem with locking up. And the escape key combo doesn't work, I'm sorry to say.
As I wrote in another post ( http://discussions.apple.com/thread.jspa?threadID=1393270&tstart=0 ) it seems (I know this will sound idiotic) to lock up only when the song name is so long that it must scroll (while the song is playing) to show the whole name (this is mainly classical music, which often has long "song" titles). It is when that annoying "flip" occurs, putting the album and song info on the reverse sides, that these Front Row locks always seem to happen. Though at other times the lock seems to come arbitrarily. Sounds very similar to all the problems described above.

Row lock class concurrency Monitor

Greetings,
We are getting ready to release my first webapp and need a �row-locking� class of sorts. For example, when a user logs in they have choices of searches where they can query the db. There is a link in the reulstSet that brings them to a detail screen. If that �detail� or row is currently open in a browser, I want to know about it.
I wonder about when a user closes their browser from the �detail� view, how can I know?
I am thinking about using a filter to track all active 'rows' and using an application scope class to track the 'locked' rows. I am developing on a Mainframe db (DMSii) that has essentially no modern capabilities. We use struts as a framework and EAServer as a container.
I could be so far from base that I am a spectator, so if there is any CONSTRUCTIVE advice or examples to point to, It would be greatly appreciated.
thanks,
mccools

You can use Rowset, RowsetEvent and RowSetListener implementation for tracking the rows.
"I wonder about when a user closes their browser from the �detail� view, how can I know?"
For this you can use the SessionBindingListener implementation.
Hope this helps.
Regards,
Rohan Kamat

Row lock on db2

we are using db2 udb v8.1, with the type 4 jcc jdbc driver. does anyone know how to create a row lock while i open a resultset? i do select ... from .. where ... for update of ...... is not working. i need to have a row lock while my cursor is move backward or forward in the resultset. thanks

I'm looking for the answer too....
anyway i want lock a row and detect row lock... for
microsoft access....good luck finding this... access doesn't support row locking.

How can I retain updates made in multiple locked rows and override scope rollback defined for row locking purposes ?

I have a set of stored procedures in SQL
One of which is called to build a list of entries to submit to a web service
Those queries are called by identical processes running on different machines, so to prevent duplicate processing we lock rows that are presently being processed.
BEGIN
TRAN TRAN1
SELECT t.[TransactionId],t.[ContentIdentifier]
FROM [dbo].[Transactions]
t WITH(READPAST,
UPDLOCK,
ROWLOCK)where
(t.Quarantined
<> 1)
COMMIT
A Second stored procedure simply updates the Quarantined flag.
My C# code
TransactionOptions transactionOptions
=
new
TransactionOptions();
transactionOptions.IsolationLevel
=
IsolationLevel.ReadCommitted;
transactionOptions.Timeout
=
new
TimeSpan(0,
10,
0);
using (TransactionScope
scopeMain =
new
TransactionScope(TransactionScopeOption.Required,
transactionOptions))
TransactionsReady = DAL.GetFilesForProcessingByServiceType(i);
using (TransactionScope
scopeSuppress =
new
TransactionScope(TransactionScopeOption.Suppress,
transactionOptions))
foreach (var
Transaction in TransactionsReady)
{ try
returnData = proxy.Submit(stuffToProcess);
using (var
scopeInner =
new System.Transactions.TransactionScope())
DAL.QuarantineTransaction(Transaction.TransactionId);
scopeInner.Complete();
scopeSuppress.Complete();
scopeMain.Complete();
The problem I experience is that if I have the Transaction Scope scopeSuppress uncommented, then the QuarantineTransaction stored procedure deadlocks.
However if I comment out the ScopeSuppress, while the process then works, if it is interrupted mid-way, then all of the Quarantine flags get reset, meaning the entire batch of items will get re-submitted next
pass (this is not desirable).
What I actually want to occur, is for the Quarantine flag to be retained on all processed records so that even if the program terminates unexpectedly, processed items remain processed but all the row locks are
released.
Does anyone know of a way to achieve this ?

The hour is late where I sit, so I don't have the time to dive into this in detail.
However, if memory serves, TransactionScopes defaults to Serializable isolation level, which may explain the deadlocks you are getting.
Erland Sommarskog, SQL Server MVP, [email protected]

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.

Error while upgrading OBIEE10g RPD to 11g Cannot release MBean - not locked

Hi,, I have successfully installed OBIEE 11g and now truing to upgrade 10g RPD to 11g RPD using Upgrade Assistant. The process gets failed with following error in the LOG file;
*[2013-02-19T00:54:53.367+05:30] [bi] [NOTIFICATION] [oracle.bi.security] Adding member 'REPORTING_USER' to role 'REPORTING_USER'*
[Comment] The above line is last line without any WARNING or ERROR, the WARNING and ERROR starts brom next line (below)
*[2013-02-19T00:56:55.375+05:30] [BIEE] [WARNING] [upgrade.BIEE] Cannot release MBean - not locked*
*[2013-02-19T00:56:55.376+05:30] [BIEE] [ERROR] [upgrade.BIEE] javax.management.OperationsException: WARNING: Element Type: DOMAIN[[*
Element Id: null
Operation Result: FAILED_TO_APPLY_CHANGES
Detail Message: Timeout; Waiting for all managed servers to push configuration changes; [120 secs]; AdminServer
Please help.
Edited by: 923934 on Feb 25, 2013 2:41 AM

while upgrading the RPD make sure that user weblogic server must be up and running including the all the BI Services.
first look into these servers and run the upgrade utility.
let me know is there any issues.
Regards,
Yogi.

UnitOfWork doesn't release pessimistic row lock???

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