Question On Table Locks

Hello,
I have a question on locks.
USER A runs a batch job of insert statements have 100000 records and does a commit after every 1000 records.
USER B is also running a batch job on similar tables and is blocked due to locks held by USER A
I have identified that USER A is blocking USER B and now i need USER B to continue with the batch job. My question is that i need to kill the USER A's session without making him lose all the data he already inserted. In short as SYS can i commit his inserted transactions on his behalf.
I assume if I kill his session he will lose all the INSERTS he performed since he hasnt commited until that point.
Please Help.

is there any way i could save the INSERTED transcations of USER A.No. User A commits or User A is killed and rolls back.
i'm also confused about this type of lock i seeIf you supply details of what the sessions are waiting on / locks held, then this will clarify.
do u suggest i commit every 500 records No. In general, you should commit at the end of a transaction - all or nothing. Committing every X is nasty.
a lot of refrential constariants with other tables and this could be causing the lockYou can get locking problems with unindexed foreign keys.
If you could provide more details of what's going on in both sessions / what they're waiting on this should clarify.

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Question about Table Locks

Hi All,
Is there any Oracle defined table/place from where we can know the details about Tables that have been locked in the current session?
Thank you.

Hi ,
To know which all objects are locked, you can use the below query :-
COLUMN owner FORMAT A20
COLUMN username FORMAT A20
COLUMN object_owner FORMAT A20
COLUMN object_name FORMAT A30
COLUMN locked_mode FORMAT A15
SELECT b.session_id AS sid,
       NVL(b.oracle_username, '(oracle)') AS username,
       a.owner AS object_owner,
       a.object_name,
       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.os_user_name
FROM   dba_objects a,
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WHERE a.object_id = b.object_id
ORDER BY 1, 2, 3, 4;Anand

About session abnormal termination, table locked question.

Hi all,
i test some table lock,after i run this statement:
select * from testt for update nowait;
i abnormal terminate session, then the table testt will be locking until after 20 minutes,
i checked some document, the parameter of SQLNET.EXPIRE_TIME = 5 in sqlnet.ora file can release that lock, i set with 5,and then test again, but still wait 20 minutes the lock can release, why?

I've changed this now to use the URL variable. I am used to using that to go from a results page to a details page where the recordset on the details page is used. I hadn't realised that you could just set a link to:
<a href="addNomination.php?LodgeID=<?php echo($_GET['LodgeID']); ?>">Add Nomination</a>
where there is no recordset on a page, just for the purposes of passing the variable. (Yeah, I know - this is probably really basic!)
I do have one last question on this though - my form action is:
<form method="post" id="form1" action="<?php echo KT_escapeAttribute(KT_getFullUri()); ?>">
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I assume this must be possible, but not sure of the exact syntax?

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?

Basic questions on row locks

Oracle 11.0.1.7
I just have a basic question about locks. What happens when 2 transactions at the same time try to delete the row? Does one get the row and other wouldn't? Is there a implicit locks that oracle takes care of?
Could you also point me to some examples or source.

That is what I have seen with for update and thought for update is for. But when I look at the oracle docs this is what it says. And what's confusing is "Permitted Operations" piece. It says other transactions can query, update etc.
A row exclusive table lock (also called a subexclusive table lock, SX) generally indicates that the transaction holding the lock has made one or more updates to rows in the table or issued SELECT ... FOR UPDATE. A row exclusive table lock is acquired automatically for a table modified by the following types of statements:
SELECT ... FROM table ... FOR UPDATE OF ...;
INSERT INTO table ... ;
UPDATE table ... ;
DELETE FROM table ... ;
LOCK TABLE table IN ROW EXCLUSIVE MODE;
A row exclusive table lock is slightly more restrictive than a row share table lock.
Permitted Operations: A row exclusive table lock held by a transaction allows other transactions to query, insert, update, delete, or lock rows concurrently in the same table. Therefore, row exclusive table locks allow multiple transactions to obtain simultaneous row exclusive and row share table locks for the same table.
Prohibited Operations: A row exclusive table lock held by a transaction prevents other transactions from manually locking the table for exclusive reading or writing. Therefore, other transactions cannot concurrently lock the table using the following statements:
LOCK TABLE table IN SHARE MODE;
LOCK TABLE table IN SHARE ROW EXCLUSIVE MODE;
LOCK TABLE table IN EXCLUSIVE MODE;

Why my question thread is locked?

I found that my question thread is locked, why?
Hi Guys,
Here are two questions about ABAP.
(1)
UML provides various diagram types. Mark the valid UML diagrams
(More than one answer is correct)
1 Aggregation
2 Composition
3 Class
4 Component
5 Behavior
I think the correct answers are (1) (2) (3). But the standard answers are (3)(4)(5).
Why?
(2)
Mark the valid logical nodes.
(More than one answer is correct)
1 Node
2 Table
3 Structure
4 Complex Data Object
5 File
The standard answers are (2) (3) (4). Can anybody explain it in details?
Thanks.
Edited by: Michael on Jan 29, 2008 3:36 PM

Hi Micheal,
The answer for the first question is:
1)
Firstly Aggregation & Composition are types of relationships and they are part of an UML Diagram used to connect the various classes/parts of that specific diagram.
They are not the actual diagrams
The remainig three options
Class,
Component &
Behavioural are the UML Diagrams, which contain the various classes,components, packages etc.
Hence the options 3,4,5 are correct.
The UML Diagrams are categorized as
Structural and Behavioural Diagrams.
Under Structural Diagrams
Class Diagram
Object Diagram
Component Diagram
Deployment Diagram
Under Behavioral Diagrams
Use Case Diagram
Sequence Diagram
Collaboration Diagram
Statechart Diagram
Activity Diagram
If you are still not clear then please go through the below link which clearly shows the various relations existing and about the UML Diagrams.
[http://www.dotnetcoders.com/web/learning/uml/diagrams/classdiagram.aspx]
Reward if useful,
Sravani.

Multiple parallel loads into one table with TABLE LOCK option

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>>>We seem to think that each parallel task will acquire its data as normal, and just won't be able to insert
until one >>>of the other parallel tasks completes its fast load.
That is correct observation.
Best Regards,Uri Dimant SQL Server MVP,
http://sqlblog.com/blogs/uri_dimant/
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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.
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the way I have tried...
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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.

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i need to following data from HR:
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i think cost place is a custom field.
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Thanks in advanced

Hi,
For Head Count you can use 0HR_PA_0 datasource and the other Employee details like start date and end date you can get them from employee master data and FTE can be calculated from the Emloyee Master Data and Head count data.
Hope this helps...
Thanks,

Time out parameter to avoid Table locking

Hi,
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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

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.
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Thank you,
- Vik.

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Table Lock DB2

Hello All,
Just wanted some advice, here is my situation.
I have a message driven bean which i want to ensure i only receive once.
So i am storing the MDB id's in a DB2 Database.
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