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.
(simple table that just stores MDB id's plus some other mdb data)
I would like to do a table lock to keep MDB reading/inserting consistency. In my transaction I would be.
check if the id is there already and an insert if its not.
I think I can use a select for update in DB2 but i have also been reading about setting isolation type of TRANSACTION_SERIALIZABLE. Which would be the best approach?

also just found another DB2 SQL statment LOCK TABLE not sure if this is another good soultion.

Similar Messages

DB2 Table locks after SAP Gui crashes

Hi,
I have a really annoying problem. Since my SAP Gui crashes sometimes, when I have nearly the limit of sessions open, I get serious problems with table locks in DB2.
Background:
When I run a program, which is updating/deleting/inserting data in SAP tables and the SAP Gui crashes, the table entries, which have been processed at that time get locked. So when SAP is then doing the roll back, the locks still exist!
The SAP basis guys have restarted the system for me, when I got this problem before, but it's really annoying, when this happens again...
I mean, of course the SAP gui shouldn't crash, but anyway the locks should be deleted by SAP during roll back, right?
Does anybody know this problem and does anybody know how to solve it without restarting the machine?
Many thanks!

Hi Markus,
true, the SAP Gui is also an issue I have to solve... But anyway the table lock should not occur.
If you think about some other situations, where the process can be interrupted:
- Calling a BAPI synchronous via RFC, which is updating/inserting/deleting table records
- Windows bluescreen
- etc....
Whatever, it is really annoying to be in the need of restarting the system, when a process is going to be interrupted...
Any ideas to this anyone?
Thank you!

Multiple parallel loads into one table with TABLE LOCK option

Hi everyone:
We have several SSIS packages where each package has the basic design of having one sequence container. Inside each sequence container can be anywhere from 2 - 9 data flow tasks where for each data is selected from a different table but all 2-9 tasks do
an OLEDB fast load (with table lock option checked) into the same single destination table.
The number of rows were pulling from the various sources might be anywhere from 5 up to 100,000.
Right now this doesn't seem to be causing any issues, but I wanted to check to see if this set up (since we're doing a review) could potentially cause problems down the road?
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. To us, that's no big deal as we're at least able to acquire the data in parallel.
What are everyone's thoughts?
Thanks!

>>>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.
--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.

Error importing a table from DB2 in OBI 10g

Hello,
I am trying to import a table from DB2, but I have the following issue:
*[nQSError: 16001] ODBC error state: S1000 code: 29986 message: [IBM][Controlador ODBC de iSeries Access][DB2 UDB]SQL0901 - Error del sistema SQL..*
Steps I have done are:
1) Create System DSN
Driver: iSeries Access ODBC Driver
2) Create a new database
Database souce definition = Database DB2/AS400
3) Create a new connection pool -->
Call interface: DB2 CLI (Unicode)
Datasource name: System name (specified in the System DSN)
I have tested with System DSN name too
Username: username DB
Password: pwd DB
c) Import table: File --> Import --> from Database
Connection Type = ODBC 3.5 and I select the System DSN created
I am working with OBI 10g (10.1.3.2.1) in Windows Server 2003 Enterprise and the DB2 is OS400 V5R4.
Thank you and regards,
Mónica.

Hi,
I have installed the DB2 client and from Access with the same ODBC is possible to import tables, but I don't understand why I can't do this operation from Administration Tool.
Do you know how can I test the ODBC? Or if it is possible to see the error with more details (any log file)? I have tested a lot of things, but I can't solve the issue.
The PATH system variable is right:
D:\oracle\bise1\bi\server\Bin;D:\oracle\bise1\bi\web\bin;D:\oracle\bise1\bi\web\catalogmanager;D:\oracle\bise1\bi\SQLAnywhere;D:\oracle\bise1\jdk\bin;D:\oracle\bise1\db\bin;D:\oracle\bise1\owb\bin;%SystemRoot%\system32;%SystemRoot%;%SystemRoot%\System32\Wbem;C:\TOOLS;C:\PROGRA~1\IBM\CLIENT~1\Shared;C:\PROGRA~1\IBM\CLIENT~1;C:\PROGRA~1\IBM\CLIENT~1\Emulator;
And in the path that it is mentioned in the error I can find the dll.
Are being doing any wrong step to import a table?
Thank you and regards,
Mónica.

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

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

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

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?

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 vs dead lock

Hi all,
could you explain the root of difference between table lock and dead lock ?
Thanks.

It's http://docs.oracle.com/cd/E11882_01/server.112/e26088/statements_9015.htm#SQLRF01605 vs. http://docs.oracle.com/cd/E11882_01/server.112/e25789/glossary.htm#CNCPT8675
Regards
Etbin

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 locking in MS SQL Server

Hi
Can anyone help with a locking problem I have. I have a jsp accessing an MS SQL 7 table. The data access has exception handling and the connection and resultset are closed within the finally block, however the table accessed sometimes gets locked preventing any updates to the records. I am using web logics jdbc driver.
Any help would be appreciated.
Dave

A quite wide issue.
Firstly, if you don't do locks, you may experince the locks other connections (by other programs) have caused.
If you do your connection with setTarnsactionIsolation( Connection.READ_UNCOMMITTED ), then you should not be influenced by other's locks. But this level is not to be recommended.
The default is Connection.READ_COMMITTED. In this level - and the higher levels as well - you are prevented from even reading a value which another connection has written, but not yet committed.
Much more locking influences, if you want to do an update.
Now, from the transaction logic only that row that is touched would have to be locked. But SQLServer has a kind of "self-deciding" locking behaviour. It starts with row locks, but if certain internal DBMS resources come low, it switches to using page locks and finally even table locks.
MS claims this as an advantage, my impression. If it is, decide on your own.
This is all described quite largely in the SQLServer docs.
We had some large discussions on this here, too. Search for "+lock +sqlserver" to find them.

Killing table locks

Hi all,
Good day..
DB version is 10.2.0.4 I need to write a script which has to kill any table locks in the DB which is more than 10 minutes.
thanks,
baskar.l

hi sb,
DECLARE
CURSOR c IS
SELECT c.owner,
      c.object_name,
      c.object_type,
      b.SID,
      b.serial#,
      b.status,
      b.osuser,
      b.machine
FROM v$locked_object a, v$session b, dba_objects c
WHERE b.SID = a.session_id AND a.object_id = c.object_id
and c.object_name in (MES.JSW_CRM_C_HR_COIL_INFO,MES.JSW_CRM_C_HR_COIL_INFO);
c_row c%ROWTYPE;
1_sql VARCHAR2(100);
BEGIN
OPEN C;
LOOP
FETCH c INTO c_row;
EXIT WHEN c%NOTFOUND;
l_sql := 'alter system kill session '''||c_row.sessionid||','||c_row.serialid||'''';
EXECUTE IMMEDIATE l_sql;
END LOOP;
CLOSE c;
END;But when executing it i get
1_sql VARCHAR2(100);
ERROR at line 15:
ORA-06550: line 15, column 1:
PLS-00103: Encountered the symbol "1" when expecting one of the following:
begin function package pragma procedure subtype type use
<an identifier> <a double-quoted delimited-identifier> form
current cursorthanks,
baskar.l

Display only for table locks

Is there a way to set up the table locks in a display only format(other than sm12).

SM12 calls function ENQUEUE_READ, which in turn calls ENQUE_READ2, which in turn moves down below the ABAP surface into the sea of C when calling the kernel function C_ENQUEUE. Best you can do is probably to build something around the two first functions, if you manage to decode the raw data obtained by the functions. It shouldn't be too difficult; SM12 is fairly straightforward and creating a display program should be feasible.
Unfortunately, even ST05 doesn't yield a result, so it seems (to me at least) that the enqueued entries (locks) reside on the server level, outside of the realm we can reach using SQL...
Regards,
Trond

Table Lock DB2

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