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  • Oracle transaction read-consistency ?

    - by trojanwarrior3000
    I have problem understanding read consistency in db(oracle). Suppose I am manger of a bank . A customer has got lock (which I dont know) and is doing some updation. Now after he has got lock I am viewing account info of the same customer and try to do some thing on it.But because of read consistency I will see data as it existed before customer got the lock. So will not that affect inputs I am getting and the decisions that I am gonna make during that period?

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  • How to set the transaction isolation level of a

    - by Michael Wiles
    How do I set the global transaction isolation level for a postgres data source. I'm running on jboss and I'm using hibernate to connect. I know that I can set the isolation level from hibernate, does this work for Postgres? This would be by setting the hibernate.connection.isolation hibernate property to 1,2,4,8 - the various values of the relevant static fields. I'm using the org.postgresql.xa.PGXADataSource

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  • What does really happen when we do a BEGIN TRAN in SQL Server 2005?

    - by Misnomer
    Hi all, I came across this issue or maybe something I didn't realize but I did a Begin Tran and had some code inside it and never ran a commit or rollback as I forgot about it. That caused all many of the database queries or even just a simple select top 1000 command were just sitting on loading..? Now it probably has put some locks on the tables I guess since it did not let me query them..but I just wanted to know what exactly happened and what are the practices to be followed here ?

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  • Question About TransactionScope in .NET

    - by peace
    using (TransactionScope scope = new TransactionScope()) { int updatedRows1 = custPh.Update(cust.CustomerID, tempPh1, 0); int updatedRows2 = custPh.Update(cust.CustomerID, tempPh2, 1); int updatedRows3 = cust.Update(); if (updatedRows1 > 0 && updatedRows2 > 0 && updatedRows3 > 0) { scope.Complete(); } } Is the above TransactionScope code structured correctly? This is my first time using it so i'm trying to make as simple as i can.

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  • How can the Three-Phase Commit Protocol (3PC) guarantee atomicity?

    - by AndiDog
    I'm currently exploring worst case scenarios of atomic commit protocols like 2PC and 3PC and am stuck at the point that I can't find out why 3PC can guarantee atomicity. That is, how does it guarantee that if cohort A commits, cohort B also commits? Here's the simplified 3PC from the Wikipedia article: Now let's assume the following case: Two cohorts participate in the transaction (A and B) Both do their work, then vote for commit Coordinator now sends precommit messages... A receives the precommit message, acknowledges, and then goes offline for a long time B doesn't receive the precommit message (whatever the reason might be) and is thus still in "uncertain" state The results: Coordinator aborts the transaction because not all precommit messages were sent and acknowledged successfully A, who is in precommit state, is still offline, thus times out and commits B aborts in any case: He either stays offline and times out (causes abort) or comes online and receives the abort command from the coordinator And there you have it: One cohort committed, another aborted. The transaction is screwed. So what am I missing here? In my understanding, if the automatic commit on timeout (in precommit state) was replaced by infinitely waiting for a coordinator command, that case should work fine.

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  • A better way to delete a list of elements from multiple tables

    - by manyxcxi
    I know this looks like a 'please write the code' request, but some basic pointer/principles for doing this the right way should be enough to get me going. I have the following stored procedure: CREATE PROCEDURE `TAA`.`runClean` (IN idlist varchar(1000)) BEGIN DECLARE EXIT HANDLER FOR NOT FOUND ROLLBACK; DECLARE EXIT HANDLER FOR SQLEXCEPTION ROLLBACK; DECLARE EXIT HANDLER FOR SQLWARNING ROLLBACK; START TRANSACTION; DELETE FROM RunningReports WHERE run_id IN (idlist); DELETE FROM TMD_INDATA_INVOICE WHERE run_id IN (idlist); DELETE FROM TMD_INDATA_LINE WHERE run_id IN (idlist); DELETE FROM TMD_OUTDATA_INVOICE WHERE run_id IN (idlist); DELETE FROM TMD_OUTDATA_LINE WHERE run_id IN (idlist); DELETE FROM TMD_TEST WHERE run_id IN (idlist); DELETE FROM RunHistory WHERE id IN (idlist); COMMIT; END $$ It is called by a PHP script to clean out old run history. It is not particularly efficient as you can see and I would like to speed it up. The PHP script gathers the ids to remove from the tables with the following query: $query = "SELECT id, stop_time FROM RunHistory WHERE config_id = $configId AND save = 0 AND NOT(stop_time IS NULL) ORDER BY stop_time"; It keeps the last five run entries and deletes all the rest. So using this query to bring back all the IDs, it determines which ones to delete and keeps the 'newest' five. After gathering the IDs it sends them to the stored procedure to remove them from the associated tables. I'm not very good with SQL, but I ASSUME that using an IN statement and not joining these tables together is probably the least efficient way I can do this, but I don't know enough to ask anything but "how do I do this better?" If possible, I would like to do this all in my stored procedure using a query to gather all the IDs except for the five 'newest', then delete them. Another twist, run entries can be marked save (save = 1) and should not be deleted. The RunHistory table looks like this: CREATE TABLE `TAA`.`RunHistory` ( `id` int(11) NOT NULL auto_increment, `start_time` datetime default NULL, `stop_time` datetime default NULL, `config_id` int(11) NOT NULL, [...] `save` tinyint(1) NOT NULL default '0', PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=0 DEFAULT CHARSET=utf8;

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  • JDBC transaction dead-lock solution required?

    - by user49767
    It's a scenario described my friend and challenged to find solution. He is using Oracle database and JDBC connection with read committed as transaction isolation level. In one of the transaction, he updates a record and executes selects statement and commits the transaction. when everything happening within single thread, things are fine. But when multiple requests are handled, dead-lock happens. Thread-A updates a record. Thread B updates another record. Thread-A issues select statement and waits for Thread-B's transaction to complete the commit operation. Thread-B issues select statement and waits for Thread-A's transaction to complete the commit operation. Now above causes dead-lock. Since they use command pattern, the base framework allows to issue commit only once (at the end of all the db operation), so they are unable to issue commit immediately after select statement. My argument was Thread-A supposed to select all the records which are committed and hence should not be issue. But he said that Thread-A will surely wait till Thread-B commits the record. is that true? What are all the ways, to avoid the above issue? is it possible to change isolation-level? (without changing underlying java framework) Little information about base framework, it is something similar to Struts action, their each and every request handled by one action, transaction begins before execution and commits after execution.

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  • What sql server isolation level should I choose to prevent concurrent reads?

    - by Brian Bolton
    I have the following transaction: SQL inserts a 1 new record into a table called tbl_document SQL deletes all records matching a criteria in another table called tbl_attachment SQL inserts multiple records into the tbl_attachment Until this transaction finishes, I don't want others users to be aware of the (1) new records in tbl_document, (2) deleted records in tbl_attachment, and (3) modified records in tbl_attachment. Would Read Committed Isolation be the correct isolation level?

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  • At which line in the following code should I commit my unit of work?

    - by Pure.Krome
    I have the following code which is in a transaction. I'm not sure where/when I should be commiting my unit of work. On purpose, I've not mentioned what type of Respoistory i'm using - eg. Linq-To-Sql, Entity Framework 4, NHibernate, etc. If someone knows where, can they please explain WHY they have said, where? (i'm trying to understand the pattern through example(s), as opposed to just getting my code to work). Here's what i've got :- using ( TransactionScope transactionScope = new TransactionScope ( TransactionScopeOption.RequiresNew, new TransactionOptions { IsolationLevel = IsolationLevel.ReadUncommitted } ) ) { _logEntryRepository.InsertOrUpdate(logEntry); //_unitOfWork.Commit(); // Here, commit #1 ? // Now, if this log entry was a NewConnection or an LostConnection, // then we need to make sure we update the ConnectedClients. if (logEntry.EventType == EventType.NewConnection) { _connectedClientRepository.Insert( new ConnectedClient { LogEntryId = logEntry.LogEntryId }); //_unitOfWork.Commit(); // Here, commit #2 ? } // A (PB) BanKick does _NOT_ register a lost connection, // so we need to make sure we handle those scenario's as a LostConnection. if (logEntry.EventType == EventType.LostConnection || logEntry.EventType == EventType.BanKick) { _connectedClientRepository.Delete( logEntry.ClientName, logEntry.ClientIpAndPort); //_unitOfWork.Commit(); // Here, commit #3 ? } _unitOfWork.Commit(); // Here, commit #4 ? transactionScope.Complete(); }

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  • JUnit test failing - complaining of missing data that was just inserted

    - by Collin Peters
    I have an extremely odd problem in my JUnit tests that I just can't seem to nail down. I have a multi-module java webapp project with a fairly standard structure (DAO's, service clasess, etc...). Within this project I have a 'core' project which contains some abstracted setup code which inserts a test user along with the necessary items for a user (in this case an 'enterprise', so a user must belong to an enterprise and this is enforced at the database level) Fairly simple so far... but here is where the strangeness begins some tests fail to run and throw a database exception where it complains that a user cannot be inserted because an enterprise does not exist. But it just created the enterprise in the preceding line of code! And there was no errors in the insertion of the enterprise. Stranger yet, if this test class is run by itself everything works fine. It is only when the test is run as part of the project that it fails! And the exact same abstracted code was run by 10+ tests before the one that fails! f I have been banging my head against a wall with this for days and haven't really made any progress. I'm not even sure what information to offer up to help diagnose this. Using JUnit 4.4, Spring 2.5.6, iBatis 2.3.0, Postgresql 8.3 Switching to org.springframework.jdbc.datasource.DriverManagerDataSource from org.apache.commons.dbcp.BasicDataSource changed the problem. Using DriverManagerDataSource the tests work for the first time, but now all of a sudden a lot of data isn't rolled back in the database! It leaves everything behind. All with no errors Tests fail when run via Eclipse & Maven Please ask for any info which may help me solve my problem!

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  • PostgreSQL pgdb driver raises "can't rollback" exception

    - by David Parunakian
    Hello, for some reason I'm experiencing the Operational Error with "can't rollback" message when I attempt to roll back my transaction in the following context: try: cursors[instance].execute("lock revision, app, timeout IN SHARE MODE") cursors[instance].execute("insert into app (type, active, active_revision, contents, z) values ('session', true, %s, %s, 0) returning id", (cRevision, sessionId)) sAppId = cursors[instance].fetchone()[0] cursors[instance].execute("insert into revision (app_id, type) values (%s, 'active')", (sAppId,)) cursors[instance].execute("insert into timeout (app_id, last_seen) values (%s, now())", (sAppId,)) connections[instance].commit() except pgdb.DatabaseError, e: connections[instance].rollback() return "{status: 'error', errno:4, errmsg: \"%s\"}"%(str(e).replace('\"', '\\"').replace('\n', '\\n').replace('\r', '\\r')) The driver in use is PGDB. What is fundamentally wrong here?

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  • Cannot save model due to bad transaction? Django

    - by Kenneth Love
    Trying to save a model in Django admin and I keep getting the error: Transaction managed block ended with pending COMMIT/ROLLBACK I tried restarting both the Django (1.2) and PostgreSQL (8.4) processes but nothing changed. I added "autocommit": True to my database settings but that didn't change anything either. Everything that Google has turned up has either not been answered or the answer involved not having records in the users table, which I definitely have. The model does not have a custom save method and there are no pre/post save signals tied to it. Any ideas or anything else I can provide to make answering this easier?

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  • How to create entities in one Entity group ?

    - by Gopi
    I am building an app based on google app engine (Java) using JDO for persistence. Can someone give me an example or a point me to some code which shows persisting of multiple entities (of same type) using javax.jdo.PersistenceManager.makePersistentAll() within a transaction. Basically I need to understand how to put multiple entites in one Entity Group so that they can be saved using makePersistentAll() inside transaction.

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  • Django: How can I protect against concurrent modification of data base entries

    - by Ber
    If there a way to protect against concurrent modifications of the same data base entry by two or more users? It would be acceptable to show an error message to the user performing the second commit/save operation, but data should not be silently overwritten. I think locking the entry is not an option, as a user might use the "Back" button or simply close his browser, leaving the lock for ever.

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  • OptimisticLockException in inner transaction ruins outer transaction

    - by Pace
    I have the following code (OLE = OptimisticLockException)... public void outer() { try { middle() } catch (OLE) { updateEntities(); outer(); } } @Transactional public void middle() { try { inner() } catch (OLE) { updateEntities(); middle(); } @Transactional public void inner() { //Do DB operation } inner() is called by other non-transactional methods which is why both middle() and inner() are transactional. As you can see, I deal with OLEs by updating the entities and retrying the operation. The problem I'm having is that when I designed things this way I was assuming that the only time one could get an OLE was when a transaction closed. This is apparently not the case as the call to inner() is throwing an OLE even when the stack is outer()->middle()->inner(). Now, middle() is properly handling the OLE and the retry succeeds but when it comes time to close the transaction it has been marked rollbackOnly by Spring. When the middle() method call finally returns the closing aspect throws an exception because it can't commit a transaction marked rollbackOnly. I'm uncertain what to do here. I can't clear the rollbackOnly state. I don't want to force create a transaction on every call to inner because that kills my performance. Am I missing something or can anyone see a way I can structure this differently? EDIT: To clarify what I'm asking, let me explain my main question. Is it possible to catch and handle OLE if you are inside of an @Transactional method? FYI: The transaction manager is a JpaTransactionManager and the JPA provider is Hibernate.

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  • multithreading with database

    - by Darsin
    I am looking out for a strategy to utilize multithreading (probably asynchronous delegates) to do a synchronous operation. I am new to multithreading so i will outline my scenario first. This synchronous operation right now is done for one set of data (portfolio) based on the the parameters provided. The (psudeo-code) implementation is given below: public DataSet DoTests(int fundId, DateTime portfolioDate) { // Get test results for the portfolio // Call the database adapter method, which in turn is a stored procedure, // which in turns runs a series of "rule" stored procs and fills a local temp table and returns it back. DataSet resultsDataSet = GetTestResults(fundId, portfolioDate); try { // Do some local processing on the results DoSomeProcessing(resultsDataSet); // Save the results in Test, TestResults and TestAllocations tables in a transaction. // Sets a global transaction which is provided to all the adapter methods called below // It is defined in the Base class StartTransaction("TestTransaction"); // Save Test and get a testId int testId = UpdateTest(resultsDataSet); // Adapter method, uses the same transaction // Update testId in the other tables in the dataset UpdateTestId(resultsDataSet, testId); // Update TestResults UpdateTestResults(resultsDataSet); // Adapter method, uses the same transaction // Update TestAllocations UpdateTestAllocations(resultsDataSet); // Adapter method, uses the same transaction // It is defined in the base class CommitTransaction("TestTransaction"); } catch { RollbackTransaction("TestTransaction"); } return resultsDataSet; } Now the requirement is to do it for multiple set of data. One way would be to call the above DoTests() method in a loop and get the data. I would prefer doing it in parallel. But there are certain catches: StartTransaction() method creates a connection (and transaction) every time it is called. All the underlying database tables, procedures are the same for each call of DoTests(). (obviously). Thus my question are: Will using multithreading anyway improve performance? What are the chances of deadlock especially when new TestId's are being created and the Tests, TestResults and TestAllocations are being saved? How can these deadlocked be handled? Is there any other more efficient way of doing the above operation apart from looping over the DoTests() method repeatedly?

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  • Spring Security ACL: NotFoundException from JDBCMutableAclService.createAcl

    - by user340202
    Hello, I've been working on this task for too long to abandon the idea of using Spring Security to achieve it, but I wish that the community will provide with some support that will help reduce the regret that I have for choosing Spring Security. Enough ranting and now let's get to the point. I'm trying to create an ACL by using JDBCMutableAclService.createAcl as follows: [code] public void addPermission(IWFArtifact securedObject, Sid recipient, Permission permission, Class clazz) { ObjectIdentity oid = new ObjectIdentityImpl(clazz.getCanonicalName(), securedObject.getId()); this.addPermission(oid, recipient, permission); } @Override @Transactional(propagation = Propagation.REQUIRED, isolation = Isolation.READ_UNCOMMITTED, readOnly = false) public void addPermission(ObjectIdentity oid, Sid recipient, Permission permission) { SpringSecurityUtils.assureThreadLocalAuthSet(); MutableAcl acl; try { acl = this.mutableAclService.createAcl(oid); } catch (AlreadyExistsException e) { acl = (MutableAcl) this.mutableAclService.readAclById(oid); } // try { // acl = (MutableAcl) this.mutableAclService.readAclById(oid); // } catch (NotFoundException nfe) { // acl = this.mutableAclService.createAcl(oid); // } acl.insertAce(acl.getEntries().length, permission, recipient, true); this.mutableAclService.updateAcl(acl); } [/code] The call throws a NotFoundException from the line: [code] // Retrieve the ACL via superclass (ensures cache registration, proper retrieval etc) Acl acl = readAclById(objectIdentity); [/code] I believe this is caused by something related to Transactional, and that's why I have tested with many TransactionDefinition attributes. I have also doubted the annotation and tried with declarative transaction definition, but still with no luck. One important point is that I have used the statement used to insert the oid in the database earlier in the method directly on the database and it worked, and also threw a unique constraint exception at me when it tried to insert it in the method. I'm using Spring Security 2.0.8 and IceFaces 1.8 (which doesn't support spring 3.0 but definetely supprorts 2.0.x, specially when I keep caling SpringSecurityUtils.assureThreadLocalAuthSet()). My AppServer is Tomcat 6.0, and my DB Server is MySQL 6.0 I wish to get back a reply soon because I need to get this task off my way

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  • Building "isolated" and "automatically updated" caches (java.util.List) in Java.

    - by Aidos
    Hi Guys, I am trying to write a framework which contains a lot of short-lived caches created from a long-living cache. These short-lived caches need to be able to return their entier contents, which is a clone from the original long-living cache. Effectively what I am trying to build is a level of transaction isolation for the short-lived caches. The user should be able to modify the contents of the short-lived cache, but changes to the long-living cache should not be propogated through (there is also a case where the changes should be pushed through, depending on the Cache type). I will do my best to try and explain: master-cache contains: [A,B,C,D,E,F] temporary-cache created with state [A,B,C,D,E,F] 1) temporary-cache adds item G: [A,B,C,D,E,F] 2) temporary-cache removes item B: [A,C,D,E,F] master-cache contains: [A,B,C,D,E,F] 3) master-cache adds items [X,Y,Z]: [A,B,C,D,E,F,X,Y,Z] temporary-cache contains: [A,C,D,E,F] Things get even harder when the values in the items can change and shouldn't always be updated (so I can't even share the underlying object instances, I need to use clones). I have implemented the simple approach of just creating a new instance of the List using the standard Collection constructor on ArrayList, however when you get out to about 200,000 items the system just runs out of memory. I know the value of 200,000 is excessive to iterate, but I am trying to stress my code a bit. I had thought that it might be able to somehow "proxy" the list, so the temporary-cache uses the master-cache, and stores all of it's changes (effectively a Memento for the change), however that quickly becomes a nightmare when you want to iterate the temporary-cache, or retrieve an item at a specific index. Also given that I want some modifications to the contents of the list to come through (depending on the type of the temporary-cache, whether it is "auto-update" or not) and I get completly out of my depth. Any pointers to techniques or data-structures or just general concepts to try and research will be greatly appreciated. Cheers, Aidos

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