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• Manage and Monitor Identity Ranges in SQL Server Transactional Replication

  - by Yaniv Etrogi

  Problem When using transactional replication to replicate data in a one way topology from a publisher to a read-only subscriber(s) there is no need to manage identity ranges. However, when using  transactional replication to replicate data in a two way replication topology - between two or more servers there is a need to manage identity ranges in order to prevent a situation where an INSERT commands fails on a PRIMARY KEY violation error  due to the replicated row being inserted having a value for the identity column which already exists at the destination database. Solution There are two ways to address this situation: Assign a range of identity values per each server. Work with parallel identity values. The first method requires some maintenance while the second method does not and so the scripts provided with this article are very useful for anyone using the first method. I will explore this in more detail later in the article. In the first solution set server1 to work in the range of 1 to 1,000,000,000 and server2 to work in the range of 1,000,000,001 to 2,000,000,000.  The ranges are set and defined using the DBCC CHECKIDENT command and when the ranges in this example are well maintained you meet the goal of preventing the INSERT commands to fall due to a PRIMARY KEY violation. The first insert at server1 will get the identity value of 1, the second insert will get the value of 2 and so on while on server2 the first insert will get the identity value of 1000000001, the second insert 1000000002 and so on thus avoiding a conflict. Be aware that when a row is inserted the identity value (seed) is generated as part of the insert command at each server and the inserted row is replicated. The replicated row includes the identity column’s value so the data remains consistent across all servers but you will be able to tell on what server the original insert took place due the range that  the identity value belongs to. In the second solution you do not manage ranges but enforce a situation in which identity values can never get overlapped by setting the first identity value (seed) and the increment property one time only during the CREATE TABLE command of each table. So a table on server1 looks like this: CREATE TABLE T1 (  c1 int NOT NULL IDENTITY(1, 5) PRIMARY KEY CLUSTERED ,c2 int NOT NULL ); And a table on server2 looks like this: CREATE TABLE T1(  c1 int NOT NULL IDENTITY(2, 5) PRIMARY KEY CLUSTERED ,c2 int NOT NULL ); When these two tables are inserted the results of the identity values look like this: Server1:  1, 6, 11, 16, 21, 26… Server2:  2, 7, 12, 17, 22, 27… This assures no identity values conflicts while leaving a room for 3 additional servers to participate in this same environment. You can go up to 9 servers using this method by setting an increment value of 9 instead of 5 as I used in this example. Continues…

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• Are we asking too much of transactional memory?

  - by Carl Seleborg

  I've been reading up a lot about transactional memory lately. There is a bit of hype around TM, so a lot of people are enthusiastic about it, and it does provide solutions for painful problems with locking, but you regularly also see complaints: You can't do I/O You have to write your atomic sections so they can run several times (be careful with your local variables!) Software transactional memory offers poor performance [Insert your pet peeve here] I understand these concerns: more often than not, you find articles about STMs that only run on some particular hardware that supports some really nifty atomic operation (like LL/SC), or it has to be supported by some imaginary compiler, or it requires that all accesses to memory be transactional, it introduces type constraints monad-style, etc. And above all: these are real problems. This has lead me to ask myself: what speaks against local use of transactional memory as a replacement for locks? Would this already bring enough value, or must transactional memory be used all over the place if used at all?

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• Transactional Messaging in the Windows Azure Service Bus

  - by Alan Smith

  Introduction I’m currently working on broadening the content in the Windows Azure Service Bus Developer Guide. One of the features I have been looking at over the past week is the support for transactional messaging. When using the direct programming model and the WCF interface some, but not all, messaging operations can participate in transactions. This allows developers to improve the reliability of messaging systems. There are some limitations in the transactional model, transactions can only include one top level messaging entity (such as a queue or topic, subscriptions are no top level entities), and transactions cannot include other systems, such as databases. As the transaction model is currently not well documented I have had to figure out how things work through experimentation, with some help from the development team to confirm any questions I had. Hopefully I’ve got the content mostly correct, I will update the content in the e-book if I find any errors or improvements that can be made (any feedback would be very welcome). I’ve not had a chance to look into the code for transactions and asynchronous operations, maybe that would make a nice challenge lab for my Windows Azure Service Bus course. Transactional Messaging Messaging entities in the Windows Azure Service Bus provide support for participation in transactions. This allows developers to perform several messaging operations within a transactional scope, and ensure that all the actions are committed or, if there is a failure, none of the actions are committed. There are a number of scenarios where the use of transactions can increase the reliability of messaging systems. Using TransactionScope In .NET the TransactionScope class can be used to perform a series of actions in a transaction. The using declaration is typically used de define the scope of the transaction. Any transactional operations that are contained within the scope can be committed by calling the Complete method. If the Complete method is not called, any transactional methods in the scope will not commit.   // Create a transactional scope. using (TransactionScope scope = new TransactionScope()) {     // Do something.       // Do something else.       // Commit the transaction.     scope.Complete(); }     In order for methods to participate in the transaction, they must provide support for transactional operations. Database and message queue operations typically provide support for transactions. Transactions in Brokered Messaging Transaction support in Service Bus Brokered Messaging allows message operations to be performed within a transactional scope; however there are some limitations around what operations can be performed within the transaction. In the current release, only one top level messaging entity, such as a queue or topic can participate in a transaction, and the transaction cannot include any other transaction resource managers, making transactions spanning a messaging entity and a database not possible. When sending messages, the send operations can participate in a transaction allowing multiple messages to be sent within a transactional scope. This allows for “all or nothing” delivery of a series of messages to a single queue or topic. When receiving messages, messages that are received in the peek-lock receive mode can be completed, deadlettered or deferred within a transactional scope. In the current release the Abandon method will not participate in a transaction. The same restrictions of only one top level messaging entity applies here, so the Complete method can be called transitionally on messages received from the same queue, or messages received from one or more subscriptions in the same topic. Sending Multiple Messages in a Transaction A transactional scope can be used to send multiple messages to a queue or topic. This will ensure that all the messages will be enqueued or, if the transaction fails to commit, no messages will be enqueued.     An example of the code used to send 10 messages to a queue as a single transaction from a console application is shown below.   QueueClient queueClient = messagingFactory.CreateQueueClient(Queue1);   Console.Write("Sending");   // Create a transaction scope. using (TransactionScope scope = new TransactionScope()) {     for (int i = 0; i < 10; i++)     {         // Send a message         BrokeredMessage msg = new BrokeredMessage("Message: " + i);         queueClient.Send(msg);         Console.Write(".");     }     Console.WriteLine("Done!");     Console.WriteLine();       // Should we commit the transaction?     Console.WriteLine("Commit send 10 messages? (yes or no)");     string reply = Console.ReadLine();     if (reply.ToLower().Equals("yes"))     {         // Commit the transaction.         scope.Complete();     } } Console.WriteLine(); messagingFactory.Close();     The transaction scope is used to wrap the sending of 10 messages. Once the messages have been sent the user has the option to either commit the transaction or abandon the transaction. If the user enters “yes”, the Complete method is called on the scope, which will commit the transaction and result in the messages being enqueued. If the user enters anything other than “yes”, the transaction will not commit, and the messages will not be enqueued. Receiving Multiple Messages in a Transaction The receiving of multiple messages is another scenario where the use of transactions can improve reliability. When receiving a group of messages that are related together, maybe in the same message session, it is possible to receive the messages in the peek-lock receive mode, and then complete, defer, or deadletter the messages in one transaction. (In the current version of Service Bus, abandon is not transactional.)   The following code shows how this can be achieved. using (TransactionScope scope = new TransactionScope()) {       while (true)     {         // Receive a message.         BrokeredMessage msg = q1Client.Receive(TimeSpan.FromSeconds(1));         if (msg != null)         {             // Wrote message body and complete message.             string text = msg.GetBody<string>();             Console.WriteLine("Received: " + text);             msg.Complete();         }         else         {             break;         }     }     Console.WriteLine();       // Should we commit?     Console.WriteLine("Commit receive? (yes or no)");     string reply = Console.ReadLine();     if (reply.ToLower().Equals("yes"))     {         // Commit the transaction.         scope.Complete();     }     Console.WriteLine(); }     Note that if there are a large number of messages to be received, there will be a chance that the transaction may time out before it can be committed. It is possible to specify a longer timeout when the transaction is created, but It may be better to receive and commit smaller amounts of messages within the transaction. It is also possible to complete, defer, or deadletter messages received from more than one subscription, as long as all the subscriptions are contained in the same topic. As subscriptions are not top level messaging entities this scenarios will work. The following code shows how this can be achieved. try {     using (TransactionScope scope = new TransactionScope())     {         // Receive one message from each subscription.         BrokeredMessage msg1 = subscriptionClient1.Receive();         BrokeredMessage msg2 = subscriptionClient2.Receive();           // Complete the message receives.         msg1.Complete();         msg2.Complete();           Console.WriteLine("Msg1: " + msg1.GetBody<string>());         Console.WriteLine("Msg2: " + msg2.GetBody<string>());           // Commit the transaction.         scope.Complete();     } } catch (Exception ex) {     Console.WriteLine(ex.Message); }     Unsupported Scenarios The restriction of only one top level messaging entity being able to participate in a transaction makes some useful scenarios unsupported. As the Windows Azure Service Bus is under continuous development and new releases are expected to be frequent it is possible that this restriction may not be present in future releases. The first is the scenario where messages are to be routed to two different systems. The following code attempts to do this.   try {     // Create a transaction scope.     using (TransactionScope scope = new TransactionScope())     {         BrokeredMessage msg1 = new BrokeredMessage("Message1");         BrokeredMessage msg2 = new BrokeredMessage("Message2");           // Send a message to Queue1         Console.WriteLine("Sending Message1");         queue1Client.Send(msg1);           // Send a message to Queue2         Console.WriteLine("Sending Message2");         queue2Client.Send(msg2);           // Commit the transaction.         Console.WriteLine("Committing transaction...");         scope.Complete();     } } catch (Exception ex) {     Console.WriteLine(ex.Message); }     The results of running the code are shown below. When attempting to send a message to the second queue the following exception is thrown: No active Transaction was found for ID '35ad2495-ee8a-4956-bbad-eb4fedf4a96e:1'. The Transaction may have timed out or attempted to span multiple top-level entities such as Queue or Topic. The server Transaction timeout is: 00:01:00..TrackingId:947b8c4b-7754-4044-b91b-4a959c3f9192_3_3,TimeStamp:3/29/2012 7:47:32 AM.   Another scenario where transactional support could be useful is when forwarding messages from one queue to another queue. This would also involve more than one top level messaging entity, and is therefore not supported.   Another scenario that developers may wish to implement is performing transactions across messaging entities and other transactional systems, such as an on-premise database. In the current release this is not supported.   Workarounds for Unsupported Scenarios There are some techniques that developers can use to work around the one top level entity limitation of transactions. When sending two messages to two systems, topics and subscriptions can be used. If the same message is to be sent to two destinations then the subscriptions would have the default subscriptions, and the client would only send one message. If two different messages are to be sent, then filters on the subscriptions can route the messages to the appropriate destination. The client can then send the two messages to the topic in the same transaction.   In scenarios where a message needs to be received and then forwarded to another system within the same transaction topics and subscriptions can also be used. A message can be received from a subscription, and then sent to a topic within the same transaction. As a topic is a top level messaging entity, and a subscription is not, this scenario will work.

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• SQL Server 2008 - Performance impact of transactional replication?

  - by cxfx

  I'm planning to set up transactional replication for a 100Gb SQL Server 2008 database. I have the distributor and publisher on the same server, and am using push subscription. Should there be a performance impact on my publisher server when it creates the initial snapshot, and synchronises it with a subscriber? From what I've tried so far on a staging server, it seems to slow right down. Is there a better way to create the initial snapshot without impacting my production publisher server?

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• Spring @Transactional not creating required transaction

  - by Steve

  Ok, so I've finally bowed to peer pressure and started using Spring in my web app :-)... So I'm trying to get the transaction handling stuff to work, and I just can't seem to get it. My Spring configuration looks like this: <?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p" xmlns:tx="http://www.springframework.org/schema/tx" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd"> <bean id="groupDao" class="mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao" lazy-init="true"> <property name="entityManagerFactory" ><ref bean="entityManagerFactory"/></property> </bean> <!-- enables interpretation of the @Required annotation to ensure that dependency injection actually occures --> <bean class="org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor"/> <!-- enables interpretation of the @PersistenceUnit/@PersistenceContext annotations providing convenient access to EntityManagerFactory/EntityManager --> <bean class="org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor"/> <!-- uses the persistence unit defined in the META-INF/persistence.xml JPA configuration file --> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalEntityManagerFactoryBean"> <property name="persistenceUnitName" value="CONOPS_PU" /> </bean> <!-- transaction manager for use with a single JPA EntityManagerFactory for transactional data access to a single datasource --> <bean id="jpaTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory"/> </bean> <!-- enables interpretation of the @Transactional annotation for declerative transaction managment using the specified JpaTransactionManager --> <tx:annotation-driven transaction-manager="jpaTransactionManager" proxy-target-class="true"/> </beans> persistence.xml: <?xml version="1.0" encoding="UTF-8"?> <persistence version="1.0" xmlns="http://java.sun.com/xml/ns/persistence" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://java.sun.com/xml/ns/persistence http://java.sun.com/xml/ns/persistence/persistence_1_0.xsd"> <persistence-unit name="CONOPS_PU" transaction-type="RESOURCE_LOCAL"> <provider>org.hibernate.ejb.HibernatePersistence</provider> ... Class mappings removed for brevity... <properties> <property name="hibernate.dialect" value="org.hibernate.dialect.Oracle10gDialect"/> <property name="hibernate.connection.autocommit" value="false"/> <property name="hibernate.connection.username" value="****"/> <property name="hibernate.connection.password" value="*****"/> <property name="hibernate.connection.driver_class" value="oracle.jdbc.OracleDriver"/> <property name="hibernate.connection.url" value="jdbc:oracle:thin:@*****:1521:*****"/> <property name="hibernate.cache.provider_class" value="org.hibernate.cache.NoCacheProvider"/> <property name="hibernate.hbm2ddl.auto" value="create"/> <property name="hibernate.show_sql" value="true"/> <property name="hibernate.format_sql" value="true"/> </properties> </persistence-unit> </persistence> The DAO method to save my domain object looks like this: @Transactional(propagation=Propagation.REQUIRES_NEW) protected final T saveOrUpdate (T model) { EntityManager em = emf.createEntityManager ( ); EntityTransaction trans = em.getTransaction ( ); System.err.println ("Transaction isActive () == " + trans.isActive ( )); if (em != null) { try { if (model.getId ( ) != null) { em.persist (model); em.flush (); } else { em.merge (model); em.flush (); } } finally { em.close (); } } return (model); } So I try to save a copy of my Group object using the following code in my test case: context = new ClassPathXmlApplicationContext(configs); dao = (GroupDao)context.getBean("groupDao"); dao.saveOrUpdate (new Group ()); This bombs with the following exception: javax.persistence.TransactionRequiredException: no transaction is in progress at org.hibernate.ejb.AbstractEntityManagerImpl.flush(AbstractEntityManagerImpl.java:301) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37) at java.lang.reflect.Method.invoke(Method.java:600) at org.springframework.orm.jpa.ExtendedEntityManagerCreator$ExtendedEntityManagerInvocationHandler.invoke(ExtendedEntityManagerCreator.java:341) at $Proxy26.flush(Unknown Source) at mil.navy.ndms.conops.common.dao.impl.jpa.GenericJPADao.saveOrUpdate(GenericJPADao.java:646) at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao.save(GroupDao.java:641) at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao$$FastClassByCGLIB$$50343b9b.invoke() at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149) at org.springframework.aop.framework.Cglib2AopProxy$DynamicAdvisedInterceptor.intercept(Cglib2AopProxy.java:622) at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDao$$EnhancerByCGLIB$$7359ba58.save() at mil.navy.ndms.conops.common.dao.impl.jpa.GroupDaoTest.testGroupDaoSave(GroupDaoTest.java:91) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:48) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:37) at java.lang.reflect.Method.invoke(Method.java:600) at junit.framework.TestCase.runTest(TestCase.java:164) at junit.framework.TestCase.runBare(TestCase.java:130) at junit.framework.TestResult$1.protect(TestResult.java:106) at junit.framework.TestResult.runProtected(TestResult.java:124) at junit.framework.TestResult.run(TestResult.java:109) at junit.framework.TestCase.run(TestCase.java:120) at junit.framework.TestSuite.runTest(TestSuite.java:230) at junit.framework.TestSuite.run(TestSuite.java:225) at org.eclipse.jdt.internal.junit.runner.junit3.JUnit3TestReference.run(JUnit3TestReference.java:130) at org.eclipse.jdt.internal.junit.runner.TestExecution.run(TestExecution.java:38) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:460) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.runTests(RemoteTestRunner.java:673) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.run(RemoteTestRunner.java:386) at org.eclipse.jdt.internal.junit.runner.RemoteTestRunner.main(RemoteTestRunner.java:196) In addition, I get the following warnings when Spring first starts. Since these reference the entityManagerFactory and the transactionManager, they probably have some bearing on the problem, but I've no been able to decipher them enough to know what: Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'entityManagerFactory' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'entityManagerFactory' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'jpaTransactionManager' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean '(inner bean)' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean '(inner bean)' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'org.springframework.transaction.interceptor.TransactionAttributeSourceAdvisor' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.context.support.AbstractApplicationContext$BeanPostProcessorChecker postProcessAfterInitialization INFO: Bean 'org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor' is not eligible for getting processed by all BeanPostProcessors (for example: not eligible for auto-proxying) Mar 11, 2010 12:19:27 PM org.springframework.beans.factory.support.DefaultListableBeanFactory preInstantiateSingletons INFO: Pre-instantiating singletons in org.springframework.beans.factory.support.DefaultListableBeanFactory@37003700: defining beans [groupDao,org.springframework.beans.factory.annotation.RequiredAnnotationBeanPostProcessor,org.springframework.orm.jpa.support.PersistenceAnnotationBeanPostProcessor,entityManagerFactory,jpaTransactionManager,org.springframework.aop.config.internalAutoProxyCreator,org.springframework.transaction.interceptor.TransactionAttributeSourceAdvisor]; root of factory hierarchy Does anyone have any idea what I'm missing? I'm totally stumped... Thanks

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• Do I need to disable access to a publisher database when setting up SQL Server 2000 Transactional Re

  - by Kev

  I have a production database i.e. where there are constant updates and I've configured this to be published to another server using Transactional Replication. When I configure transactional replication I've been doing the following: disable access to the source database backup source DB then restore to subscription server configure replication re-enable DB access to our apps The problem with this approach is scheduling in downtime, having to suspend all the various timed scheduled tasks we run and shutting down access to our various applications that are dependant on this database. Can I just configure transactional replication without disabling access to the publishing database and the subscriber database will correctly catch up? i.e. are all the DML statements queued on the publisher and as soon as the subscriber is ready they are picked off and executed?

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• How do you implement Software Transactional Memory?

  - by Joseph Garvin

  In terms of actual low level atomic instructions and memory fences (I assume they're used), how do you implement STM? The part that's mysterious to me is that given some arbitrary chunk of code, you need a way to go back afterward and determine if the values used in each step were valid. How do you do that, and how do you do it efficiently? This would also seem to suggest that just like any other 'locking' solution you want to keep your critical sections as small as possible (to decrease the probability of a conflict), am I right? Also, can STM simply detect "another thread entered this area while the computation was executing, therefore the computation is invalid" or can it actually detect whether clobbered values were used (and thus by luck sometimes two threads may execute the same critical section simultaneously without need for rollback)?

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• Designing & Maintaining SQL Server Transactional Replication Environments

  Microsoft IT protects against unplanned Transactional Replication outages and issues by using best practices and proactive monitoring. This results in increased stability, simplified management and improved performance of transactional replication environments. New! SQL Backup Pro 7.2 - easy, automated backup and restoresTry out the latest features and get faster, smaller, verified backups. Download a free trial.

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• Steps to Rename a Subscriber Database for SQL Server Transactional Replication

  I have transactional replication configured in production. The business team has a requirement to rename the subscription database. Is it possible to rename the subscription database and ensure that transactional replication will continue to function as before? If so, how could we achieve this? Get smart with SQL Backup ProPowerful centralised management, encryption and more.SQL Backup Pro was the smartest kid at school. Discover why.

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• Why is it possible to save entity but not delete if transactional annotation is set to readonly=true

  - by jakob

  Hello experts! My class is annotated with org.springframework.transaction.annotation.Transactional like this: @Transactional(readOnly = true) public class MyClass { I then have a dao class: @Override public void delete(final E entity) { getSession().delete(entity); } @Override public void save(final E entity) { getSession().saveOrUpdate(entity); } Then I have two methods in MyClass @Transactional(readOnly = false) public void doDelete(Entity entity){ daoImpl.delete(entity) } //@Transactional(readOnly = false) public void doSave(){ daoImpl.save(entity) } Saving and deleting works like a charm. But if I remove the @Transactional(readOnly = false) on doDelete method deletion stops working, Saving works with and without the method annotation. So my question is: WHY?

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• Transactional Interceptors in Java EE 7 - Request for feedback

  - by arungupta

  Linda described how EJB's container-managed transactions can be applied to the Java EE 7 platform as a whole using a solution based on CDI interceptors. This can then be used by other Java EE components as well, such as Managed Beans. The plan is to add an annotation and standardized values in the javax.transaction package. For example: @Inherited @InterceptorBinding @Target({TYPE, METHOD}) @Retention(RUNTIME) public @interface Transactional { TxType value() default TxType.REQUIRED } And then this can be specified on a class or a method of a class as: public class ShoppingCart { ... @Transactional public void checkOut() {...} ... } This interceptor will be defined as part of the update to Java Transactions API spec at jta-spec.java.net. The Java EE 7 Expert Group needs your help and looking for feedback on the exact semantics. The complete discussion can be read here. Please post your feedback to [email protected] and we'll also consider comments posted to this entry.

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• TXPAUSE : polite waiting for hardware transactional memory

  - by Dave

  Classic locks are an appropriate tool to prevent potentially conflicting operations A and B, invoked by different threads, from running at the same time. In a sense the locks cause either A to run before B or vice-versa. Similarly, we can replace the locks with hardware transactional memory, or use transactional lock elision to leverage potential disjoint access parallelism between A and B. But often we want A to wait until B has run. In a Pthreads environment we'd usually use locks in conjunction with condition variables to implement our "wait until" constraint. MONITOR-MWAIT is another way to wait for a memory location to change, but it only allows us to track one cache line and it's only available on x86. There's no similar "wait until" construct for hardware transactions. At the instruction-set level a simple way to express "wait until" in transactions would be to add a new TXPAUSE instruction that could be used within an active hardware transaction. TXPAUSE would politely stall the invoking thread, possibly surrendering or yielding compute resources, while at the same time continuing to track the transaction's address-set. Once a transaction has executed TXPAUSE it can only abort. Ideally that'd happen when some other thread modifies a variable that's in the transaction's read-set or write-set. And since we're aborting all writes would be discarded. In a sense this gives us multi-location MWAIT but with much more flexibility. We could also augment the TXPAUSE with a cycle-count bound to cap the time spent stalled. I should note that we can already enter a tight spin loop in a transaction to wait for updates to address-set to cause an abort. Assuming that the implementation monitors the address-set via cache-coherence probes, by waiting in this fashion we actually communicate via the probes, and not via memory values. That is the updating thread signals the waiter via probes instead of by traditional memory values. But TXPAUSE gives us a polite way to spin.

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• Replicating A Volume Of Large Data via Transactional Replication

  During weekend maintenance, members of the support team executed an UPDATE statement against the database on the OLTP Server. This database was a part of Transactional Replication, and once the UPDATE statement was executed the Replication procedure came to a halt with an error message. Satnam Singh decided to work on this case and try to find an efficient solution to rebuild the procedure without significant downtime.

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• What is causing Error 15165 in my MSSQL Transactional Replication subscription agent?

  - by Ryan

  Microsoft SQL Server 2008 (SP1) Standard running on Windows 2008. Bidirectional transactional replication is set up between two servers. One of the subscription agents just started getting error 15164. The results of sp_helpsubscriptionerrors is: Source: MSSQL_ENG Error: 15165 Text: Could not find object '(null)' or you do not have permission. Command Id: 320 I have made sure that the SQL Server agent login has both Windows and SQL security access. Full access to the directory structure and sysadmin access to the SQL Server. What else can I do to try to troubleshoot/fix this? Thanks!

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• Can I add a delay to sql server transactional replication ?

  - by Brann

  I've got transactional replication configured from a database called DBProd to another database called DBWarehouse ; everything works fine, and transaction are usually replicated instantaneously to the warehouse .... which is my problem. I'd like to add a slight delay to the replication (something like 10 minutes), so that the replicated database can be used to access a previous version of the database (in case a bug occurs for example) Is there a simple way to achieve this ?

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• SQL SERVER – Reducing CXPACKET Wait Stats for High Transactional Database

  - by pinaldave

  While engaging in a performance tuning consultation for a client, a situation occurred where they were facing a lot of CXPACKET Waits Stats. The client asked me if I could help them reduce this huge number of wait stats. I usually receive this kind of request from other client as well, but the important thing to understand is whether this question has any merits or benefits, or not. Before we continue the resolution, let us understand what CXPACKET Wait Stats are. The official definition suggests that CXPACKET Wait Stats occurs when trying to synchronize the query processor exchange iterator. You may consider lowering the degree of parallelism if a conflict concerning this wait type develops into a problem. (from BOL) In simpler words, when a parallel operation is created for SQL Query, there are multiple threads for a single query. Each query deals with a different set of the data (or rows). Due to some reasons, one or more of the threads lag behind, creating the CXPACKET Wait Stat. Threads which came first have to wait for the slower thread to finish. The Wait by a specific completed thread is called CXPACKET Wait Stat. Note that CXPACKET Wait is done by completed thread and not the one which are unfinished. “Note that not all the CXPACKET wait types are bad. You might experience a case when it totally makes sense. There might also be cases when this is also unavoidable. If you remove this particular wait type for any query, then that query may run slower because the parallel operations are disabled for the query.” Now let us see what the best practices to reduce the CXPACKET Wait Stats are. The suggestions, with which you will find that if you search online through the browser, would play a major role as and might be asked about their jobs In addition, might tell you that you should set ‘maximum degree of parallelism’ to 1. I do agree with these suggestions, too; however, I think this is not the final resolutions. As soon as you set your entire query to run on single CPU, you will get a very bad performance from the queries which are actually performing okay when using parallelism. The best suggestion to this is that you set ‘the maximum degree of parallelism’ to a lower number or 1 (be very careful with this – it can create more problems) but tune the queries which can be benefited from multiple CPU’s. You can use query hint OPTION (MAXDOP 0) to run the server to use parallelism. Here is the two-quick script which helps to resolve these issues: Change MAXDOP at Server Level EXEC sys.sp_configure N'max degree of parallelism', N'1' GO RECONFIGURE WITH OVERRIDE GO Run Query with all the CPU (using parallelism) USE AdventureWorks GO SELECT * FROM Sales.SalesOrderDetail ORDER BY ProductID OPTION (MAXDOP 0) GO Below is the blog post which will help you to find all the parallel query in your server. SQL SERVER – Find Queries using Parallelism from Cached Plan Please note running Queries in single CPU may worsen your performance and it is not recommended at all. Infect this can be very bad advise. I strongly suggest that you identify the queries which are offending and tune them instead of following any other suggestions. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: SQL, SQL Authority, SQL Optimization, SQL Performance, SQL Query, SQL Server, SQL Tips and Tricks, SQL White Papers, SQLAuthority News, T SQL, Technology

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• autocommit and @Transactional and Cascading with spring, jpa and hibernate

  - by subes

  Hi, what I would like to accomplish is the following: have autocommit enabled so per default all queries get commited if there is a @Transactional on a method, it overrides the autocommit and encloses all queries into a single transaction, thus overriding the autocommit if there is a @Transactional method that calls other @Transactional annotated methods, the outer most annotation should override the inner annotaions and create a larger transaction, thus annotations also override eachother I am currently still learning about spring-orm and couldn't find documentation about this and don't have a test project for this yet. So my questions are: What is the default behaviour of transactions in spring? If the default differs from my requirement, is there a way to configure my desired behaviour? Or is there a totally different best practice for transactions? --EDIT-- I have the following test-setup: @javax.persistence.Entity public class Entity { @Id @GeneratedValue private Integer id; private String name; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } } @Repository public class Dao { @PersistenceContext private EntityManager em; public void insert(Entity ent) { em.persist(ent); } @SuppressWarnings("unchecked") public List<Entity> selectAll() { List<Entity> ents = em.createQuery("select e from " + Entity.class.getName() + " e").getResultList(); return ents; } } If I have it like this, even with autocommit enabled in hibernate, the insert method does nothing. I have to add @Transactional to the insert or the method calling insert for it to work... Is there a way to make @Transactional completely optional?

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• lazyinializationexception with transactional annotation in messageconvert

  - by Karl

  Hi, I have a Rest-Service exposed through spring-mvc. I have a particular method which is correctly mapped and called through a http-call. My spring application contains the hibernatetransactionmanager and transactions are configured through @Transactional-annotations. I annotated the method with @Transactional. @Transactional(readOnly = true) @Override @RequestMapping(value = "/start", method = RequestMethod.GET) @ResponseBody public List start(....) Whenever I call the http-method I get org.hibernate.LazyInitializationException from my org.springframework.http.converter.json.MappingJacksonHttpMessageConverter which is bound in my application context. Is the @Transactional annotation valid for the MessageConverter as well?

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• Strange befaviour of spring transaction support for JPA + Hibernate +@Transactional annotation

  - by abovesun

  I found out really strange behavior on relatively simple use case, probably I can't understand it because of not deep knowledges of spring @Transactional nature, but this is quite interesting. I have simple User dao that extends spring JpaDaoSupport class and contains standard save method: @Transactional public User save(User user) { getJpaTemplate().persist(user); return user; } If was working fine until I've add new method to same class: User getSuperUser(), this method should return user with isAdmin == true, and if there is no super user in db, method should create one. Thats how it was looking like: public User createSuperUser() { User admin = null; try { admin = (User) getJpaTemplate().execute(new JpaCallback() { public Object doInJpa(EntityManager em) throws PersistenceException { return em.createQuery("select u from UserImpl u where u.admin = true").getSingleResult(); } }); } catch (EmptyResultDataAccessException ex) { User admin = new User('login', 'password'); admin.setAdmin(true); save(admin); // THIS IS THE POINT WHERE STRANGE THING COMING OUT } return admin; } As you see code is strange forward and I was very confused when found out that no transaction was created and committed on invocation of save(admin) method and no new user wasn't actually created despite @Transactional annotation. In result we have situation: when save() method invokes from outside of UserDAO class - @Transactional annotation counted and user successfully created, but if save() invokes from inside of other method of the same dao class - @Transactional annotation ignored. Here how I was change save() method to force it always create transaction. public User save(User user) { getJpaTemplate().execute(new JpaCallback() { public Object doInJpa(EntityManager em) throws PersistenceException { em.getTransaction().begin(); em.persist(user); em.getTransaction().commit(); return null; } }); return user; } As you see I manually invoke begin and commit. Any ideas?

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• Hibernate @Transactional not starting transaction

  - by rhinds

  I have a web app using Hibernate, and I am attempting to persist some data, but it is failing to persist within a Transaction despite using the @Transactional annotation. My service class is as follows: @Service("profileService") public class ProfileService { private EntityManager entityManager; @Autowired private AccountService accountService; @Autowired private ProfileDAOImpl profileDao; @PersistenceContext public void setEntityManager(EntityManager em) { this.entityManager = em; } @Transactional public void addConnectionToAccount(SocialConnection sc) { entityManager.persist(sc); } } The addConnectionToAccount() method is being called from another Spring bean in a normal method, and the ProfileService class is currently being injected there: public class HibernateConnectionRepository implements ConnectionRepository { @Inject private ProfileService profileService; @Override @Transactional public void addConnection(SocialConnection sc) { try { profileService.addConnectionToAccount(accountId, sc); } catch (Exception e) { e.printStackTrace(); } } I tried putting the @Transactional annotation on the calling method in the vain hope that it might make a difference but nothing. Previously I have experienced problems like this its been because the object being persisted does not satisfy table restrictions (such as non-nullable columns as null) or because the method is being called from within the same class and the calling method is not Transactional, but neither of those are the case here.. Any ideas? it just fails silently, the logs are as follows: 2012-03-26 22:25:04,702 [http-bio-8085-exec-9] DEBUG com.mchange.v2.resourcepool.BasicResourcePool - trace com.mchange.v2.resourcepool.BasicResourcePool@1bc25c8 [managed: 3, unused: 2, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@e5b006) 2012-03-26 22:25:04,710 [http-bio-8085-exec-9] DEBUG org.hibernate.SQL - select SEQ_COUNT from SEQUENCE where SEQ_NAME = 'PO_SEQ' for update 2012-03-26 22:25:04,711 [http-bio-8085-exec-9] DEBUG org.hibernate.SQL - update SEQUENCE set SEQ_COUNT = ? where SEQ_COUNT = ? and SEQ_NAME = 'PO_SEQ' 2012-03-26 22:25:04,723 [http-bio-8085-exec-9] DEBUG com.mchange.v2.resourcepool.BasicResourcePool - trace com.mchange.v2.resourcepool.BasicResourcePool@1bc25c8 [managed: 3, unused: 2, excluded: 0] (e.g. com.mchange.v2.c3p0.impl.NewPooledConnection@e5b006) 2012-03-26 22:25:04,723 [http-bio-8085-exec-9] DEBUG org.hibernate.event.internal.AbstractSaveEventListener - Generated identifier: 2200, using strategy: org.hibernate.id.MultipleHiLoPerTableGenerator UPDATE Also wanted to mention that the HibernateConnectionRepository bean is not annotated and is actually being configured in an @Configuration class (if this makes any difference? not used @Configuration classes much). The method to create the bean is as follows: @Bean @Scope(value = "request", proxyMode = ScopedProxyMode.INTERFACES) public ConnectionRepository connectionRepository() { Authentication authentication = SecurityContextHolder.getContext().getAuthentication(); if (authentication == null) { throw new IllegalStateException("Unable to get a ConnectionRepository: no user signed in"); } ApplicationUser user = (ApplicationUser) authentication.getPrincipal(); return usersConnectionRepository().createConnectionRepository(String.valueOf(user.getAccountId())); } The bean is scoped to the logged in user, but may also be created multiple times for each user..

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• Hibernate Session flush behaviour [ and Spring @Transactional ]

  - by EugeneP

  I use Spring and Hibernate in a web-app, SessionFactory is injected into a DAO bean, and then this DAO is used in a Servlet through webservicecontext. DAO methods are transactional, inside one of the methods I use ... getCurrentSession().save(myObject); One servlet calls this method with an object passed. The update seems to not be flushed at once, it takes about 5 seconds to see the changes in the database. The servlet's method in which that DAO's update method is called, takes a fraction of second to complete. After the @Transactional method of DAO is completed, flushing may NOT happen ? It does not seem to be a rule [ I already see it ]. Then the question is this: what to do to force the session to flush after every DAO method? It may not be a good thing to do, but talking about a Service layer, some methods must end with immediate flush, and Hibernate Session behavior is not predictable. So what to do to guarantee that my @Transactional method persists all the changes after the last line of that method code? getCurrentSession().flush() is the only solution? p.s. I read somewhere that @Transactional IS ASSOCIATED with a DB Transaction. Method returns, transaction must be committed. I do not see this happens.

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• SQL 2008 Log Reader fails with 'Could not execute sp_replcmds" - Transactional Replication

  - by JoeJoe

  Transactional Replication. Two servers SQL server 2008sp1 using domain account. If I make a small dummy setup it works fine. If I use copy of my Production database it fails with MSSQL_REPL20011 error 'could not execute sp_replcmds'.(and MSSQL error 15517, and MSSQL_REPL22037). I've restarted the Agent - no good. How do I troubleshoot this to find root cause?

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• Using both RolesAllowed and Transactional in beans

  - by Laran Evans

  I have some beans which contain methods which are annotated with both @RolesAllowed and @Transactional. I have one Spring config file which utilizes a BeanNameAutoProxyCreator for Security related beans and another Spring config file which utilizes a BeanNameAutoProxyCreator for Transactional related beans. The problem is that some beans contain both security as well as transactional-related beans. So Spring creates proxies for one set of beans. It then tries to create proxies for the other set of beans. When it does, it tries to create proxies of the proxies and bombs out. Has anyone tried to configure both security and transactionality in the same beans via Spring? What's the trick? Thanks.

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• Forcing a method to be non-transactional in JPA (Eclipselink)

  - by rhinds

  Hi, I am developing an application using Eclipselink and as part of the app I need to be able to manipulate some of the objects which involves changing data without it being persisted to the database (i merging/changing objects for some batch generation processes). I am reluctant to change the data in the Entity objects, as there is a risk that even though i have not marked the methods as @Transactional, this method could in the future be inadvertantly called from within a transactional method and these changes could be persisted. So my question is, is there anyway to get around this? Such as force a method to always be non-transactional regardless; terminate any transactionality as soon as the method is started; etc. I know there is a .detach() method that can detach the objects from the Entity Manager, however, there are many objects and this seems like a potentially error prone fail-safe on my code.

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• Spring @Transactional Annotation Best Practice

  - by Thomas Einwaller

  We are currently discussing the Best Practice for placing the @Transactional annotations in our code. Do you place the @Transactional in the DAO classes and/or their methods or is it better to annotate the Service classed which are calling using the DAO objects? Or does it make sense to annotate both "layers"?

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