Table Locks times release? Urgent Plz

Hi
I am using 9i and concerned about the locks that my application obtains. Is it possible to release all the locks on a table that are opened and forgotten. i mean set a timeout for opened connection?
Appreciate your help.
Thanks

I am locking the table from an application and the application might crash without commit or rollback.
I have multiple threads running who will wait to get a lock on the table. If one thread crashes, i dont want the other threads to wait indefinitely. Ideally i would want the Lock to be released in 1 sec.
Thanks for the reply.

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REG: How to add elements onto htmlb table cell.. URGENT PLZ HELP

Hi all,
I have created a htmlb table. And the jsp code is as follows
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Hi,
Have you tried looking at the examples that come with the PDK for all of the HTMLB elements? From memory, there should be a small table example or 2 that have different types of columns shown similar to what you want - they have the full source code with them for you to look at.
If you are working in a portal, go to the Java Developer tab and I "think" there should be a tab linking to HTMLB documentation and examples - sorry I can't be more specific but I don't have access to a portal at the moment so am trying to remember.
Gareth.

Time out parameter to avoid Table locking

Hi,
I am looking at any configurable parameter if any for setting the time out parameter to avoid Table locking.Now what's happening is : If i run select ...for update from one session,oracle is applying a lock till i do a commit.And if i run the same query from another session,it takes unspecified time without returning any error.Using the query with NOWAIT options does not serve my purpose.
Any help in this regard is appreciated
Thanks
Sam

Are you looking for a way to time out the original query, or are you looking for a way for the second query to wait for some time and then abort if it is unable to lock the row(s)?
Justin
Distributed Database Consulting, Inc.
www.ddbcinc.com

How to release table locks?

I was running Data Services (4.0 SP2) to load data into Hana (1.0 SP2 patch 20) using the Bulk load option. Apparently, the DS process hung and now the table I was writing to is locked although the DS Job is dead. How do you release the table lock without restarting Hana DB?

Hello Sachin,
you could try these statements. The first one will cancel the currently executed operation, the second one will disconnect the idle session:
ALTER SYSTEM CANCEL SESSION session_id;
ALTER SYSTEM DISCONNECT SESSION session_id;
Regards,
Mark

Releasing table locks when user closes browser

Hi, I've read the blogs and tried some of the code that people have suggested but it just never seems to work. I have locked table entries belonging to a stateful 2003 BSP. The user closes the browser by means of the 'X' and the table locks remain. I have table lock releases in the 'OnDestroy' event but that never seems to occur. I have tried inserting JavaScript to capture the closing of the window but either it captures every other event or it gets confused when navigating to another page. I have the redirect examples however they all seem to be part of a proper logoff procedure, rather than the cowboy approach of just shutting down the browser. There must be a simple procedure out there to do this. Is there a complete example somewhere?
Any help will be appreciated,
Kevin

Hi Raja, ok I discovered why it isn't working and it really is quite obvious. The browser that it's being tested on has a Google toolbar installed. Among other things this toolbar allows users to block the display of popups. If this is selected the script will not run properly as it needs the alert to allow the server side to run. This is going to be frustrating because while most of the user's desktop is managed by the corporation they still have the ability to add toolbars to their browsers and configure them, and I'm sure most people will select the popup blocker.
Kevin

Can't open and lock time zone table error on every open

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Release table lock

how to release table lock in Oracle?

If you know the sid and serial# (query V$SESSION for that) of the other user then you (or your DBA) can issue:
SQL> ALTER SYSTEM KILL SESSION 'sid,serial#';
http://www.oracle-base.com/articles/misc/killing-oracle-sessions.php

Is there a way to create a temp table each time someone hits a procedure?

I am creating a procedure in Oracle 10g to take data from Oracle to be put in a cognos report. The problem with creating a perminent table is that several people will be running this report at the same time, which means the procedure will be run each time someone runs this report. The perminent table will either drop the old data or the data will get mixed up which means the different peoples reports will not be correct. I tried putting a lock on the tables that would release the lock once one person was done running their report but that didn't work. I suggested we put the data directly into the cursor but what happens when more than one person runs this procedure at the same time?
Any help on figuring out how to resolve this would be greatly appreciated.

Hi,
If there is one table 100 people inserting in the same table, i dont see a problem.
Few things you will have to take care of.
When you are retireving the data from teh table to show on the report,
how will you identify it is for which user, obviously you store the user name too.
Now this table will grow in size, so make sure when the report is exited you delete rows from teh table only pertainign to the user.
Over a period of time you will face more problmes of slow response due to continous deletes because of something called as HWM.
So make sure you also gatehr statistics for the table at regular intervals.
So,
1) Store user while isnerting, retrieve data only for that user in teh report
2) delete data on report exit only for that user
3) gather statistics for table at regual intervals.
4) Ofcourse Build indexed for "good" response time, but Benchmark against you data whatever you are doing.Cheers!!!
Bhushan

Configuring profile parameter for a table lock object

Hi Experts-
I want to set the 'wait time' (_WAIT) parameter as a profile parameter for a table lock object.
I have created a lock object on a ZTable. I lock and unlock this object in exclusive non-cumulative mode through the enqueue and dequeue lock object function modules. These generated FMs are invoked via my custom function module.
My function module will run in the background as a scheduled task in R/3. I execute the Enqueue FM at the start of the FM and keep the table locked until the last step finishes in my FM and then I Dequeue it. I want to have the processing wait and retry the Enqueuring FM at set intervals in case the one run doesn't finish entirely and a new run of this same job kicks off.
Thank you,
- Vik.

Set the wait parameter = 'X'. These means that if it encounters a lock, then it will wait a certain time for the lock to be released. This certain time is a system value set by your basis team. I don't imagine it being a very long time.
CALL FUNCTION 'ENQUEUE_EZPIPHYINVREF'
       EXPORTING
            MODE_ZPIPHYINVREF = 'E'
            MANDT             = SY-MANDT
            _WAIT             = 'X'.
Regards,
Rich Heilman

Identifying deadlocked resources in graph with 1 row lock and 1 table lock

Hi, I have run into repeated occurrences of the deadlock graph at the bottom of this post and have a few questions about it:
1. It appears that proc 44, session 548 is holding a row lock (X). Is the waiter, proc 30, session 542, trying to acquire a row lock (X) also or an exclusive table lock (X) on the table containing that row?
2. Under what circumstances would something hold a row exclusive table lock (SX) and want to upgrade that to a share row exclusive table lock (SSX)?
3. Our table cxml_foldercontent has a column 'structuredDataId' with a FK to cxml_structureddata.id and an ON DELETE SET NULL trigger. Would this help explain why an "update" to one table (i.e.g cxml_foldercontent) would also need to acquire a lock in a foreign table, cxml_structureddata?
4. What is the difference between "Current SQL statement:" and "Current SQL statement for this session:"? That terminology is confusing. Is session 542 executing the "update" or the "delete"?
5. In the "Rows waited on:" section is it saying that Session 542 is waiting on on obj - rowid = 0000BE63 - AAAL5jAAGAAA6tZAAK or that it is has the lock on that row and other things are waiting on it?
A couple of notes:
- the cxml_foldercontent.structuredDataId FK column has an index on it already
Deadlock graph:
                       ---------Blocker(s)-------- ---------Waiter(s)---------
Resource Name                    process session holds waits process session holds waits
TX-003a0011-000003d0        44       548     X               30        542             X
TM-0000be63-00000000       30       542     SX              44        548     SX    SSX
session 548: DID 0001-002C-000002D9     session 542: DID 0001-001E-00000050
session 542: DID 0001-001E-00000050     session 548: DID 0001-002C-000002D9
Rows waited on:
Session 542: obj - rowid = 0000BE63 - AAAL5jAAGAAA6tZAAK
(dictionary objn - 48739, file - 6, block - 240473, slot - 10)
Session 548: no row
Information on the OTHER waiting sessions:
Session 542:
pid=30 serial=63708 audsid=143708731 user: 41/CASCADE
O/S info: user: cascade, term: unknown, ospid: 1234, machine:
            program: JDBC Thin Client
application name: JDBC Thin Client, hash value=2546894660
Current SQL Statement:
update cascade.cxml_foldercontent set name=:1 , lockId=:2 , isCurrentVersion=:3 , versionDate=:4 , metadataId=:5 , permissionsId=:6 , workflowId=:7 , isWorkingCopy=:8 , parentFolderId=:9 , relativeOrder=:10 , cachePath=:11 , isRecycled=:12 , recycleRecordId=:13 , workflowComment=:14 , draftUserId=:15 , siteId=:16 , prevVersionId=:17 , nextVersionId=:18 , originalCopyId=:19 , workingCopyId=:20 , displayName=:21 , title=:22 , summary=:23 , teaser=:24 , keywords=:25 , description=:26 , author=:27 , startDate=:28 , endDate=:29 , reviewDate=:30 , metadataSetId=:31 , expirationNoticeSent=:32 , firstExpirationWarningSent=:33 , secondExpirationWarningSent=:34 , expirationFolderId=:35 , maintainAbsoluteLinks=:36 , xmlId=:37 , structuredDataDefinitionId=:38 , pageConfigurationSetId=:39 , pageDefaultConfigurationId=:40 , structuredDataId=:41 , pageStructuredDataVersion=:42 , shouldBeIndexed=:43 , shouldBePublished=:44 , lastDatePublished=:45 , lastPublishedBy=:46 , draftOriginalId=:47 , contentTypeId=:48 where id=:49
End of information on OTHER waiting sessions.
Current SQL statement for this session:
delete from cascade.cxml_structureddata where id=:1

Mohamed Houri wrote:
What is important for a foreign key is to be indexed (of course if the parent table is deleted/merged/updated, or if a performance reason imposes it). Wether this index is unique or not doesn't matter (as far as i know).But, you should ask your self the following question : what is the meaning of having a 1 to 1 relationship between a parent and a child table ? if you succeed to create a unique index on your FK then this means that for each PK value corresponds at most one FK value!! Isn't it? is this what you want to have?Thanks, as I mentioned above, cxml_structureddata is actually the child table of cxml_foldercontent with 1 or more records' owningEntityId referring to rows in cxml_foldercontent. The reason for the FK on cxml_foldercontent.structuredDataId is a little ambiguous but it explained above.
Will a TX-enqueue held on mode X always be waited on by another TX-enqueue row lock X? Or can it be waited on by an Exclusive (X) table lock?Not really clear. Sorry, are you saying my question is unclear or it's not clear why type of eXclusive lock session 542 is trying to acquire in the first line of the trace? Do you think that the exclusive lock being held by session 548 in the first line is on rows in cxml_foldercontent (due to the ON DELETE SET NULL on these child rows) or rows in the cxml_structureddata that it's actually deleting?
Is there any way for me to tell for certain?
The first enqueue is a TX (Transaction Enqueue) held by session 548 on mode X (exclusive). This session represents the blocking session. At the same time the locked row is waited on by the blocked session (542) and the wait is on mode X (exclusive). So put it simply, we have here session 542 waiting for session 548 to release it lock (may be by commiting/roll backing). At this step we are not in presence of a deadlock.
The second line of the deadlock graph shows that session 542 is the blocking session and it is doing a TM enqueue (DML lock) held on SX(Shared eXclusive). While session 548(which is the waiting session) is blocked by session 542 and is waiting on SSX mode.
Here we see that 548 is blocking session 542 via a TX enqueue and session 542 is blocking session 548 via a TM enqueue ---> That is the deadlock. Oracle will then immediately choose arbitrarlly a victim session (542 or 548) and kill its process letting the remaining session continuing its work.
That is your situation explained here.Thanks, any idea why session 542 (the DELETE from cxml_structureddata) would be trying to upgrade it's lock to SSX? Is this lock mode required to update a child tables foreign key columns when using an ON DELETE SET NULL trigger? Having read more about SSX, I'm not sure I understand in what cases it's used. Is there a way for me to confirm with 100% certainty specifically which tables in the TM enqueue locks are being held on? Is session 548 definitely trying to acquire an SSX mode on my cxml_foldecontent table or could it be cxml_structureddata table?
(a) Verify that all your FK are indexed (be carreful that the FK columns should be at the leading edge of the index)Thanks, we've done this already. When you say the "leading edge" you mean for a composite index? These indexes are all single column.
(b) Verify the logic of the DML against cxml_foldercontentCan you be more specific? Any idea what I'm looking for?

Reliable detect number of occurences (table lock needed or ?)

Hi all,
I got an issue with detecting duplicate messages. Database clients process files and messages and create a hash value that is passed on to the database. The database should return the number of occurences of this hash value in the last (e.g) 14 days.
create table HashHistory ( ID NUMBER,
MESSAGEHASH VARCHAR2 (20),
TS TIMESTAMP);
create sequence SomeSequence;
insert into HashHistory values (SomeSequence.nextval,'first hash', systimestamp);
insert into HashHistory values (SomeSequence.nextval,'second hash', systimestamp);
create or replace procedure DuplDetection (p_HashIn varchar2,
                                     p_occurences OUT number) AS
l_timestamp timestamp default systimestamp;
begin
-- possible exclusive table lock here... lock table HashHistory in exclusive mode;
insert into HashHistory values (SomeSequence.nextval, p_HashIn, l_timestamp);
select count (1)
into p_occurences
FROM HashHistory
where MESSAGEHASH = p_HashIn
and   TS < l_timestamp
and   TS > l_timestamp-14;
commit; --to release the table lock if applicable
end;When this procedure is called by two different machines at the same time with the same new hash value ('third hash'). One session should return 0 while the other should return 1 as number of occurences.... With default Oracle behaviour using row level locks, and executing them in parallel both sessions will not be able to see the others sessions hash values, and both will return 0 occurences. Is an exclusive table lock my only option to enforce this behaviour or can I trust Oracle to handle this correctly?
I expect 10^6 hashes each day and possible up to 10 or 20 clients running at the same time generating and checking these hash values. What are the changes of both sessions returning the same value without an exclusive table lock (as in this example)? What other parameters would you consider?
I am on Oracle Database 10g Enterprise Edition Release 10.2.0.4.0 - 64bi

Nicosa wrote:
Hi,
Wouldn'that work if you do it as follows ?insert into HashHistory values (SomeSequence.nextval, p_hashIn,...);
commit;
select count (1)
into p_occurences
FROM HashHistory
where MESSAGEHASH = p_HashIn
and   TS > l_timestamp-14
and ID!=SomeSequence.currval;The second session should see that some others existing hash were inserted, and hence an be warned.No, it wouldn't work. Some kind of synchronization is required.
In multi-threaded environment you cannot predict the order of execution of this program.
Let say we have a server with only one processor and 3 users (sessions) connected to that server.
Three users (let say U1, U2 and U3) call this procedure to insert the same hash. The procedure has 3 operations: insert, commit, select,
and assume theoretically that these 3 operation are atomic (each takes only one processor cycle - in reality each of these operations can consume thousands of cycles).
Server can execute these calls in this order:
U1-insert (sequence + 1)
U1-commit
U1-select (returns 0)
U2-insert (sequence + 1)
U2-commit
U2-select (returns 1)
U3-insert (sequence + 1)
U3-commit
U3-select (returns 2)
- in this scenario results will be OK.
But the order might be:
U1-insert (sequence + 1)
U1-commit
- here server decides to switch to another process/thread
U2-insert (sequence + 1)
U2-commit
- server switches to proccess 3
U3-insert (sequence + 1)
U3-commit
- server switches back to U2
U2-Select (user 2 sees record commited by U1 and U3 and returns 2)
- server switches to U3
U3-Select (user 1 sees record commited by U1 and U2 and returns 2)
- server switches to U1
U1 - Select (this also returns 2)
- results are 2,2,2, but should be 0,1,2
If 20 users cal this procedure at the same moment with the same hash value, it is even possible that each user gets 19 as the final result,
but proper results should be 0, 1, 2, 3 .... 19 ;)
Without some kind of synchronization this a lottery.
There is also another trap with the sequence - consider this example:
Session 1
SQL> create sequence abc;
Sequence created.
SQL> select abc.nextval from dual connect by level <=5;
   NEXTVAL
      1
      2
      3
      4
      5
SQL> select abc.currval from dual;
   CURRVAL
      5Session 2
SQL> select abc.nextval from dual;
   NEXTVAL
      6
SQL> select abc.nextval from dual connect by level <=5;
   NEXTVAL
      7
      8
      9
     10
     11
SQL> select abc.currval from dual;
   CURRVAL
     11Back to session 1
SQL> select abc.currval from dual;
   CURRVAL
      5What happens in this scenario:
- user 1 does insert (select nextval from the sequence)
- user 2,3,4,5,6 ..... 100 call the procedure just 3 microseconds after U1 and do insert (increase the sequence)
- user 1 retrieve currval from the sequence ?

To find the table lock

Hi
When i try to update a able it is locked.
May i know how to find out by whom was the lock created.
Thanks in advance
Mary

No that's not possible, because Oracle doesn't keep track of all the individual locks. Oracle doesn't have a lock manager and they are not a scarce resource in Oracle.
There are two thing you can do, although both are probably not what you want:
1) Examine the table locks, and if there is only one on the table you are working with, you have a chance that the session you find is the one you are looking for. But this is only true when the lock is held for quite some time. Otherwise you risk the situation that the session you were interested in, has released the lock and a new session has a new lock on the table. So handle with care.
2) When your session is waiting for a lock, there will be a record in v$lock. Use a third session to examine which session is holding the lock.
Regards,
Rob.

Share Table Locks (S)

Hi All,
I'm using version - Oracle Database 10g Enterprise Edition Release 10.2.0.1.0 - Prod
Oracle doc(relase 10.2) - A share table lock is acquired automatically for the table specified in the following statement:
LOCK TABLE table IN SHARE MODE;
Permitted Operations: A share table lock held by a transaction allows other transactions only to query the table, to lock specific rows with SELECT ... FOR UPDATE, or to run LOCK TABLE ... IN SHARE MODE statements successfully.
--It means...if table is locked in share mode ,than other transaction can fire <select * from table_name where ... for update> statment.
the way I have tried...
Scott_1> lock table t_chk in share mode;
scott_> select * from t_chk where a = 10 for update; <this stmt waits for scott_1 to fire rollback or commit>
than Pls let me know what is meaning of --<to lock specific rows with SELECT ... FOR UPDATE> in above explation.
source -
http://download.oracle.com/docs/cd/B19306_01/server.102/b14220/consist.htm#sthref1939

Hi,
if I understand what you are asking...
Lock for update tells the database that you have locked your database set for UPDATE purposes.
So if you attempt to do this with a data set that it is currently being updated then your code fails when it tries to reserve and no updates are done.
If you do it and some tries to update the same data whilst you have it locked for update, then there update will be pending the completion of yours, and will not be allowed to happen until after you finish.
If someone else attempts to Lock for Update whilst you have your lock for update then there code will fail and no updates are done by them...
As for SELECT - as SQL updates are either committed (have happened) or not - then the user will always get a read consistent result, but your locks never prevent their snapshots allowing normal query behaviour.
Make sense??
regards,
Robert.

Disk space transaction and temp table lock in oracle

Hi,
Today many sessions used to get disk space transaction lock and temp table lock and i am seeing these locks first time in my Production database,
is there any workaround to avoid this contension.
Thanks
Prakash GR

Post your version (all 3 decimal places).
Post the SELECT statement and results that have led you to this conclusion.
Other than the fact that you have seen a number what, precisely, is the issue.

Table lock

How to release the table lock DBMS_LOCK..

RELEASE....
http://docs.oracle.com/cd/E11882_01/appdev.112/e25788/d_lock.htm#ARPLS66761

Table Locks times release? Urgent Plz

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