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• SQL SERVER – Table Variables and Transactions – SQL in Sixty Seconds #007 – Video

  - by pinaldave

  Today’s SQL in Sixty Seconds video is inspired from my presentation at TechEd India 2012 on Misconception and Resolution. Quite often I have seen people getting confused with certain behavior of the T-SQL. They expect SQL to behave certain way and SQL Server behave differently. This kind of issue often creates confusion and frustration. Sometime I have seen them also confusing it with bug and submitting the bug, where reality is totally different. Similar concept which are going to see today. I have seen quite commonly developer assuming that table various will be rolled back when transaction is rolled back. This sixty seconds video describes that table various are not rolled back when transactions are rolled back. More on Errors: Difference Temp Table and Table Variable – Effect of Transaction Effect of TRANSACTION on Local Variable – After ROLLBACK and After COMMIT Debate – Table Variables vs Temporary Tables – Quiz – Puzzle – 13 of 31 I encourage you to submit your ideas for SQL in Sixty Seconds. We will try to accommodate as many as we can. Reference: Pinal Dave (http://blog.sqlauthority.com) Filed under: Database, Pinal Dave, PostADay, SQL, SQL Authority, SQL in Sixty Seconds, SQL Query, SQL Scripts, SQL Server, SQL Tips and Tricks, SQLServer, T SQL, Video

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• How atomic is a SELECT INTO?

  - by leo.pasta

  Last week I got an interesting situation that prompted me to challenge a long standing assumption. I always thought that a SELECT INTO was an atomic statement, i.e. it would either complete successfully or the table would not be created. So I got very surprised when, after a “select into” query was chosen as a deadlock victim, the next execution (as the app would handle the deadlock and retry) would fail with: Msg 2714, Level 16, State 6, Line 1 There is already an object named '#test' in the database. The only hypothesis we could come up was that the “create table” part of the statement was committed independently from the actual “insert”. We can confirm that by capturing the “Transaction Log” event on Profiler (filtering by SPID0). The result is that when we run: SELECT * INTO #results FROM master.sys.objects we get the following output on Profiler: It is easy to see the two independent transactions. Although this behaviour was a surprise to me, it is very easy to workaround it if you feel the need (as we did in this case). You can either change it into independent “CREATE TABLE / INSERT SELECT” or you can enclose the SELECT INTO in an explicit transaction: SET XACT_ABORT ON BEGIN TRANSACTION SELECT * INTO #results FROM master.sys.objects COMMIT

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• Can Near Field Communications (NFC) Benefit your Supply Chain?

  - by Stephen Slade

  Leading firms continue to leverage the latest tools and technologies to drive performance especially around minimizing transaction costs. With razor thin margins in manufacturing and distribution, the leading producers are resorting to Near Field Communications to gain efficiencies.  In this week’s CIO magazine (Apr1, 2012, pg.30, see http://www.cio.com)  Lauren Brousell talks of the things you need to know to make a more informed decision with NFC.  Sandy Shen of Gartner says NFC appeals because "it supports any services that requires data transfer and authentication' 1. NFC is Cheap and Easy - short range transmitting technology connecting smartphones to data transfer. 2. Adoption Seems Inevitable - more merchants will use NCF for payments in the futures. Wallets are becoming obsolete. 3. It's a Hot Potato for Enterprise - Business with credit card companies and cell phone providers are debating who handles the billing process. 4. It's in use Overseas. Japan uses FeliCa to pay by smartphone. In the US, billing agreements are causing territorial conflict. 5. Security Risks Come Standard. As people lose HH devices, security will be an ongoing concern. Credentials and timeout features and alleviate to some extent. My prediction: In 5 years, we won't have wallets in our pockets.  Our secure and all-powerful smart phones will be our electronic portable banks and execute the transaction for us based on our preferences and propensities and electronically execute the transaction for the supply chain.

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• Deleting a row from self-referencing table

  - by Jake Rutherford

  Came across this the other day and thought “this would be a great interview question!” I’d created a table with a self-referencing foreign key. The application was calling a stored procedure I’d created to delete a row which caused but of course…a foreign key exception. You may say “why not just use a the cascade delete option?” Good question, easy answer. With a typical foreign key relationship between different tables which would work. However, even SQL Server cannot do a cascade delete of a row on a table with self-referencing foreign key. So, what do you do?…… In my case I re-wrote the stored procedure to take advantage of recursion:   -- recursively deletes a Foo ALTER PROCEDURE [dbo].[usp_DeleteFoo]      @ID int     ,@Debug bit = 0    AS     SET NOCOUNT ON;     BEGIN TRANSACTION     BEGIN TRY         DECLARE @ChildFoos TABLE         (             ID int         )                 DECLARE @ChildFooID int                        INSERT INTO @ChildFoos         SELECT ID FROM Foo WHERE ParentFooID = @ID                 WHILE EXISTS (SELECT ID FROM @ChildFoos)         BEGIN             SELECT TOP 1                 @ChildFooID = ID             FROM                 @ChildFoos                             DELETE FROM @ChildFoos WHERE ID = @ChildFooID                         EXEC usp_DeleteFoo @ChildFooID         END                                    DELETE FROM dbo.[Foo]         WHERE [ID] = @ID                 IF @Debug = 1 PRINT 'DEBUG:usp_DeleteFoo, deleted - ID: ' + CONVERT(VARCHAR, @ID)         COMMIT TRANSACTION     END TRY     BEGIN CATCH         ROLLBACK TRANSACTION         DECLARE @ErrorMessage VARCHAR(4000), @ErrorSeverity INT, @ErrorState INT         SELECT @ErrorMessage = ERROR_MESSAGE(), @ErrorSeverity = ERROR_SEVERITY(), @ErrorState = ERROR_STATE()         IF @ErrorState <= 0 SET @ErrorState = 1         INSERT INTO ErrorLog(ErrorNumber,ErrorSeverity,ErrorState,ErrorProcedure,ErrorLine,ErrorMessage)         VALUES(ERROR_NUMBER(), @ErrorSeverity, @ErrorState, ERROR_PROCEDURE(), ERROR_LINE(), @ErrorMessage)         RAISERROR (@ErrorMessage, @ErrorSeverity, @ErrorState)     END CATCH   This procedure will first determine any rows which have the row we wish to delete as it’s parent. It then simply iterates each child row calling the procedure recursively in order to delete all ancestors before eventually deleting the row we wish to delete.

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• Relationships in a Chen ERD

  - by Nibroc A Rehpotsirhc

  I am working on a Chen ERD to model our organizations merchandise. Our central entity is a Style. We have supplemental entities of Color and Season. I am defining our assortment as the relationship between these three entities, and this relationship itself will have attributes and is defined by the three entities which participate in the mandatory relationship. The rules are; Many Styles can be offered in a Season, and a Style can be offered in many Seasons. Within a Season, a Style can be offered in Many Colors. I then have 2 other entities, one of which I believe is a weak entity, Climate, and the other may be weak, but I am not sure, this being Transaction Channel. I am thinking of these as relationships off of a relationship? Meaning, for a given Style/Color combination offered in a Season, it can be available through 1 or more Transaction Channels. Additionally, within a season, a given Style/Color combination can be intended for 1 or more Climates. Is it valid to have relationships off of relationships? Or does this requirement dictate that I should think of this Style/Color/Season relationship as an entity itself, and define the relationships to Climate and Transaction Channel off of this entity?

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• Implementing the transport layer for a SIP UAC

  - by Jonathan Henson

  I have a somewhat simple, but specific, question about implementing the transport layer for a SIP UAC. Do I expect the response to a request on the same socket that I sent the request on, or do I let the UDP or TCP listener pick up the response and then route it to the correct transaction from there? The RFC does not seem to say anything on the matter. It seems that especially using UDP, which is connection-less, that I should just let the listeners pick up the response, but that seems sort of counter intuitive. Particularly, I have seen plenty of UAC implementations which do not depend on having a Listener in the transport layer. Also, most implementations I have looked at do not have the UAS receiving loop responding on the socket at all. This would tend to indicate that the client should not be expecting a reply on the socket that it sent the request on. For clarification: Suppose my transport layer consists of the following elements: TCPClient (Sends Requests for a UAC via TCP) UDPClient (Sends Requests for a UAC vid UDP) TCPSever (Loop receiving Requests and dispatching to transaction layer via TCP) UDPServer (Loop receiving Requests and dispatching to transaction layer via UDP) Obviously, the *Client sends my Requests. The question is, what receives the Response? The *Client waiting on a recv or recvfrom call on the socket it used to send the request, or the *Server? Conversely, the *Server receives my requests, What sends the Response? The *Client? doesn't this break the roles of each member a bit?

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• What is a Relational Database Management System (RDBMS)?

  A Relational Database Management System (RDBMS)  can also be called a traditional database that uses a Structured Query Language (SQL) to provide access to stored data while insuring the integrity of the data. The data is stored in a collection of tables that is defined by relationships between data items. In addition, data permitted to be joined in new relationships. Traditional databases primarily process data through transactions called transaction processing. Transaction processing is the methodology of grouping related business operations based predefined business events. An example of this can be seen when a person attempts to purchase an item from an online e-tailor. The business must execute specific operations for a related  business event. In this case, a business must store the following information: Customer Info, Order Info, Order Item Info, Customer Payment Data, Payment Results, and Current Order Status. Example: Pseudo SQL Operations needed for processing an online e-tailor sale. Insert Customer into Customers Insert New Order into Orders Insert Each New Order Item into OrderItems Insert Customer Payment Info into PaymentInfo Insert Payment Processing Result into PaymentDetails Update Customer for Current Order Status Common Relational Database Management System Microsoft SQL Server Microsoft Access Oracle MySQL DB2 It is important to note that no current RDBMS has fully implemented all of the Relational Principles. Common RDBMS Traits Volatile Data Supports Transaction Processing Optimized for Updates and Simple Queries 

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• NHibernate, transactions and TransactionScope

  - by Erik

  I'm trying to find the best solution to handle transaction in a web application that uses NHibernate. We use a IHttpModule and at HttpApplication.BeginRequest we open a new session and we bind it to the HttpContext with ManagedWebSessionContext.Bind(context, session); We close and unbind the session on HttpApplication.EndRequest. In our Repository base class, we always wrapped a transaction around our SaveOrUpdate, Delete, Get methods like, according to best practice: public virtual void Save(T entity) { var session = DependencyManager.Resolve<ISession>(); using (var transaction = session.BeginTransaction()) { session.SaveOrUpdate(entity); transaction.Commit(); } } But then this doesn't work, if you need to put a transaction somewhere in e.g. a Application service to include several repository calls to Save, Delete, etc.. So what we tried is to use TransactionScope (I didn't want to write my own transactionmanager). To test that this worked, I use an outer TransactionScope that doesn't call .Complete() to force a rollback: Repository Save(): public virtual void Save(T entity) { using (TransactionScope scope = new TransactionScope()) { var session = Depe.ndencyManager.Resolve<ISession>(); session.SaveOrUpdate(entity); scope.Complete(); } } The block that uses the repository: TestEntity testEntity = new TestEntity { Text = "Test1" }; ITestRepository testRepository = DependencyManager.Resolve<ITestRepository>(); testRepository.Save(testEntity); using (var scope = new TransactionScope()) { TestEntity entityToChange = testRepository.GetById(testEntity.Id); entityToChange.Text = "TestChanged"; testRepository.Save(entityToChange); } TestEntity entityChanged = testRepository.GetById(testEntity.Id); Assert.That(entityChanged.Text, Is.EqualTo("Test1")); This doesn't work. But to me if NHibernate supports TransactionScope it would! What happens is that there is no ROLLBACK at all in the database but when the testRepository.GetById(testEntity.Id); statement is executed a UPDATE with SET Text = "TestCahgned" is fired instead (It should have been fired between BEGIN TRAN and ROLLBACK TRAN). NHibernate reads the value from the level1 cache and fires a UPDATE to the database. Not expected behaviour!? From what I understand whenever a rollback is done in the scope of NHibernate you also need to close and unbind the current session. My question is: Does anyone know of a good way to do this using TransactionScope and ManagedWebSessionContext?

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• SQL Server 2008 Filestream Impersonation Access Denied error

  - by Adi

  I've been trying to upload a file to the database using SQL SERVER 2008 Filestream and Impersonation technique to save the file in the file system, but i keep getting Access Denied error; even though i've set the permissions for the impersonating user to the Filestream folder(C:\SQLFILESTREAM\Dev_DB). when i debugged the code, i found the server return a unc path(\Server_Name\MSSQLSERVER\v1\Dev_LMDB\dbo\FileData\File_Data\13C39AB1-8B91-4F5A-81A1-940B58504C17), which was not accessible through windows explorer. I've my web application hosted on local maching(Windows 7). SQL Server is located on a remote server(Windows Server 2008 R2). Sql authentication was used to call the stored procedure. Following is the code i've used to do the above operations. SqlCommand sqlCmd = new SqlCommand("AddFile"); sqlCmd.CommandType = CommandType.StoredProcedure; sqlCmd.Parameters.Add("@File_Name", SqlDbType.VarChar, 512).Value = filename; sqlCmd.Parameters.Add("@File_Type", SqlDbType.VarChar, 5).Value = Path.GetExtension(filename); sqlCmd.Parameters.Add("@Username", SqlDbType.VarChar, 20).Value = username; sqlCmd.Parameters.Add("@Output_File_Path", SqlDbType.VarChar, -1).Direction = ParameterDirection.Output; DAManager PDAM = new DAManager(DAManager.getConnectionString()); using (SqlConnection connection = (SqlConnection)PDAM.CreateConnection()) { connection.Open(); SqlTransaction transaction = connection.BeginTransaction(); WindowsImpersonationContext wImpersonationCtx; NetworkSecurity ns = null; try { PDAM.ExecuteNonQuery(sqlCmd, transaction); string filepath = sqlCmd.Parameters["@Output_File_Path"].Value.ToString(); sqlCmd = new SqlCommand("SELECT GET_FILESTREAM_TRANSACTION_CONTEXT()"); sqlCmd.CommandType = CommandType.Text; byte[] Context = (byte[])PDAM.ExecuteScalar(sqlCmd, transaction); byte[] buffer = new byte[4096]; int bytedRead; ns = new NetworkSecurity(); wImpersonationCtx = ns.ImpersonateUser(IMP_Domain, IMP_Username, IMP_Password, LogonType.LOGON32_LOGON_INTERACTIVE, LogonProvider.LOGON32_PROVIDER_DEFAULT); SqlFileStream sfs = new SqlFileStream(filepath, Context, System.IO.FileAccess.Write); while ((bytedRead = inFS.Read(buffer, 0, buffer.Length)) != 0) { sfs.Write(buffer, 0, bytedRead); } sfs.Close(); transaction.Commit(); } catch (Exception ex) { transaction.Rollback(); } finally { sqlCmd.Dispose(); connection.Close(); connection.Dispose(); ns.undoImpersonation(); wImpersonationCtx = null; ns = null; } } Can someone help me with this issue. Reference Exception: Type : System.ComponentModel.Win32Exception, System, Version=2.0.0.0, Culture=neutral, PublicKeyToken=b77a5c561934e089 Message : Access is denied Source : System.Data Help link : NativeErrorCode : 5 ErrorCode : -2147467259 Data : System.Collections.ListDictionaryInternal TargetSite : Void OpenSqlFileStream(System.String, Byte[], System.IO.FileAccess, System.IO.FileOptions, Int64) Stack Trace : at System.Data.SqlTypes.SqlFileStream.OpenSqlFileStream(String path, Byte[] transactionContext, FileAccess access, FileOptions options, Int64 allocationSize) at System.Data.SqlTypes.SqlFileStream..ctor(String path, Byte[] transactionContext, FileAccess access, FileOptions options, Int64 allocationSize) at System.Data.SqlTypes.SqlFileStream..ctor(String path, Byte[] transactionContext, FileAccess access) Thanks

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• When transactionManager is not named "transactionManager" ...

  - by smallufo

  I am trying Spring 3(.0.2.RELEASE) and JPA2 and Hibernate 3.5.1-Final... One thing upsets me is that spring seems only accept a transaction Manager named "transactionManager" If I don't name it "transactionManager" , Spring will throws NoSuchBeanDefinitionException: No bean named 'transactionManager' is defined. Here is my config : <context:component-scan base-package="destiny.data.mining"/> <context:annotation-config/> <bean id="miningEntityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="mining"/> </bean> <bean id="miningTransactionManager" class="org.springframework.orm.jpa.JpaTransactionManager" > <property name="entityManagerFactory" ref="miningEntityManagerFactory"/> </bean> <tx:advice id="txAdviceMining" transaction-manager="miningTransactionManager"> <tx:attributes> <tx:method name="get*" read-only="true"/> <tx:method name="save*" propagation="REQUIRED"/> <tx:method name="update*" propagation="REQUIRED"/> <tx:method name="delete*" propagation="REQUIRED"/> <tx:method name="*" propagation="SUPPORTS" read-only="true"/> </tx:attributes> </tx:advice> <aop:config> <aop:pointcut id="methods" expression="execution(* destiny.utils.AbstractDao+.*(..))"/> <aop:advisor advice-ref="txAdviceMining" pointcut-ref="methods"/> </aop:config> <tx:annotation-driven transaction-manager="miningTransactionManager"/> In this config , an Entity Manager Factory is not necessarily named "entityManagerFactory" , and "txAdvice" is not necessarily named "txAdvice" , either. But I don't know why on earth Spring requires a transaction manager named "transactionManager" ? Is there any way not to name a transaction manager "transactionManager" ? (I'm running multiple spring config files , so I try my best to avoid name-conflicting) test code : @RunWith(SpringJUnit4ClassRunner.class) @ContextConfiguration(locations={"classpath:mining.xml"}) public class MiningPersonDaoTest { @Inject private EntityManagerFactory miningEntityManagerFactory; @Inject private MiningPersonDao miningPersonDao; @Transactional @Test public void testUpdate() { MiningPerson p = miningPersonDao.get(42L); p.setLocationName("OOXX"); miningPersonDao.update(p); System.out.println(p); } } ii

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• MySQL Connect 8 Days Away - Replication Sessions

  - by Mat Keep

  Following on from my post about MySQL Cluster sessions at the forthcoming Connect conference, its now the turn of MySQL Replication - another technology at the heart of scaling and high availability for MySQL. Unless you've only just returned from a 6-month alien abduction, you will know that MySQL 5.6 includes the largest set of replication enhancements ever packaged into a single new release: - Global Transaction IDs + HA utilities for self-healing cluster..(yes both automatic failover and manual switchover available!) - Crash-safe slaves and binlog - Binlog Group Commit and Multi-Threaded Slaves for high performance - Replication Event Checksums and Time-Delayed replication - and many more There are a number of sessions dedicated to learn more about these important new enhancements, delivered by the same engineers who developed them. Here is a summary Saturday 29th, 13.00 Replication Tips and Tricks, Mats Kindahl In this session, the developers of MySQL Replication present a bag of useful tips and tricks related to the MySQL 5.5 GA and MySQL 5.6 development milestone releases, including multisource replication, using logs for auditing, handling filtering, examining the binary log, using relay slaves, splitting the replication stream, and handling failover. Saturday 29th, 17.30 Enabling the New Generation of Web and Cloud Services with MySQL 5.6 Replication, Lars Thalmann This session showcases the new replication features, including • High performance (group commit, multithreaded slave) • High availability (crash-safe slaves, failover utilities) • Flexibility and usability (global transaction identifiers, annotated row-based replication [RBR]) • Data integrity (event checksums) Saturday 29th, 1900 MySQL Replication Birds of a Feather In this session, the MySQL Replication engineers discuss all the goodies, including global transaction identifiers (GTIDs) with autofailover; multithreaded, crash-safe slaves; checksums; and more. The team discusses the design behind these enhancements and how to get started with them. You will get the opportunity to present your feedback on how these can be further enhanced and can share any additional replication requirements you have to further scale your critical MySQL-based workloads. Sunday 30th, 10.15 Hands-On Lab, MySQL Replication, Luis Soares and Sven Sandberg But how do you get started, how does it work, and what are the best practices and tools? During this hands-on lab, you will learn how to get started with replication, how it works, architecture, replication prerequisites, setting up a simple topology, and advanced replication configurations. The session also covers some of the new features in the MySQL 5.6 development milestone releases. Sunday 30th, 13.15 Hands-On Lab, MySQL Utilities, Chuck Bell Would you like to learn how to more effectively manage a host of MySQL servers and manage high-availability features such as replication? This hands-on lab addresses these areas and more. Participants will get familiar with all of the MySQL utilities, using each of them with a variety of options to configure and manage MySQL servers. Sunday 30th, 14.45 Eliminating Downtime with MySQL Replication, Luis Soares The presentation takes a deep dive into new replication features such as global transaction identifiers and crash-safe slaves. It also showcases a range of Python utilities that, combined with the Release 5.6 feature set, results in a self-healing data infrastructure. By the end of the session, attendees will be familiar with the new high-availability features in the whole MySQL 5.6 release and how to make use of them to protect and grow their business. Sunday 30th, 17.45 Scaling for the Web and the Cloud with MySQL Replication, Luis Soares In a Replication topology, high performance directly translates into improving read consistency from slaves and reducing the risk of data loss if a master fails. MySQL 5.6 introduces several new replication features to enhance performance. In this session, you will learn about these new features, how they work, and how you can leverage them in your applications. In addition, you will learn about some other best practices that can be used to improve performance. So how can you make sure you don't miss out - the good news is that registration is still open ;-) And just to whet your appetite, listen to the On-Demand webinar that presents an overview of MySQL 5.6 Replication.  

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• Seamless STP with Oracle SOA Suite

  - by user12339860

  STP stands for “Straight Through Processing”. Wikipedia describes STP as a solution that enables “the entire trade process for capital markets and payment transactions to be conducted electronically without the need for re-keying or manual intervention, subject to legal and regulatory restrictions” .I will deal with the later part of the definition i.e “payment transactions without manual intervention” in this article. The STP that I am writing about involves the interaction between a Bank and its’ corporate customers,to that extent this business case is also called “Corporate Payments”.Simply put a  Corporate Payment-STP solution needs to connect the payment transaction right from the Corporate ERP into the Bank’s Payment Hub. A SOA based STP solution can do a lot more than just process transaction. But before I get to the solution let me describe the perspectives of the two primary parties in this interaction. The Corporate customer and the Bank. Corporate's Interaction with Bank:  Typically it is the treasury department of an enterprise which interacts with the Bank on a daily basis. Here is how a day of interaction would look like from the treasury department of a corp. Corporate Cash Retrieve Beginning of day totals Monitor Cash Accounts Send or receive cash between accounts Supply chain payments Payment Settlements Calculate settlement positions Retrieve End of Day totals Assess Transaction Financial Impact Short Term Investment Desk Retrieve Current Account information Conduct Investment activities Bank’s Interaction with the Corporate :  From the Bank’s perspective, the interaction starts from the point of on boarding a corporate customer to billing the corporate for the value added services it provides. Once the corporate is on-boarded the daily interaction involves Handle the various formats of data arriving from customers Process Beginning of Day & End of Day reporting request from customers Meet compliance requirements Process Payments Transmit Payment Status Challenges with this Interaction :  Both the Bank & the Corporate face many challenges from these interactions. Some of the challenges include Keeping a consistent view of transaction data for various LOBs of the corporate & the Bank Corporate customers use different ERPs, hence the data formats are bound to be different Can the Bank’s IT systems convert the data formats that can be easily mapped to the corporate ERP How does the Bank manage the communication profiles of these customers?  Corporate customers are demanding near real time visibility on their corporate accounts Corporate customers can make better cash management decisions if they can analyse the impact. Can the Bank create opportunities to sell its products to the investment desks at corporate houses & manage their orders? How will the Bank bill the corporate customer for the value added services it provides. What does a SOA based Seamless STP solution bring to the table? Highlights of Oracle SOA based STP solution For the Corporate Customer: No Manual or Paper based banking transactions Secure Delivery of Payment data to the Bank from multiple ERPs without customization Single Portal for monitoring & administering payment transactions Rule based validation of payments Customer has data necessary for more effective handling of payment and cash management decisions  Business measurements track progress toward payment cost goals  For the Bank: Reduces time & complexity of transactions Simplifies the process of introducing new products to corporate customers Single Payment hub for all corporate ERP payments across multiple instruments New Revenue sources by delivering value added services to customers Leverages existing payment infrastructure Remove Inconsistent data formats and interchange between bank and corporate systems  Compliance and many other benefits

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• Achieving NHibernate Nested Transactions Behavior

  - by jfneis

  Hi all, I'm trying to achieve some kind of nested transaction behavior using NHibernate's transaction control and FlushMode options, but things got a little bit confusing after too much reading, so any confirmation about the facts I list below will be very usefull. What I want is to open one big transaction that splits in little transactions. Imagine the following scenario: TX1 opens a TX and inserts a Person's record; TX2 opens a TX and updates this Person's name to P2; TX2 commits; TX3 opens a TX and updates this Person's name to P3; TX3 rollbacks; TX1 commits; I'd like to see NH sending the INSERT and the TX2 UPDATE to the database, just ignoring what TX3, as it was rolled back. I tried to use FlushMode = Never and only flushing the session after the proper Begins/Commits/Rollbacks have been demanded, but NH always update the database with the object's final state, independent of commits and rollbacks. Is that normal? Does NH really ignores transactional control when working with FlushMode = Never? I've also tried to use FlushMode = Commit and openning the nested transactions, but I discovered that, because ADO.NET, the nested transactions are, actually, always the same transaction. Note that I'm not trying to achieve a "all or nothing" behavior. I'm looking more to a savepoint way of working. Is there a way to do that (savepoints) with NH? Thank you in advance. Filipe

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• We have multiple app servers running against a single database. How do I ensure that each row in a q

  - by Dave

  We have about 7 app servers running .NET windows services that ping a single sql server 2005 queue table and fetch a fixed amount of records to process at fixed intervals. The amount of records to process and the amount of time between fetches are both configurable and are initially set to 100 and 30 seconds initially. Currently, my queue table has an int status column which can be either "Ready, Processing, Complete, Error". The proc that fetches the records has a sql transaction with the following code inside the transaction: 1) Fetch x number of records into temp table where the status is "Ready". The select uses a holdlock hint 2) Update the status on those records in the Queue table to "Processing" The .NET services do some processing that may take seconds or even minutes per record. Another proc is called per record that simply updates the status to "Complete". The update proc has no transaction as I'm leaning on the implicit transaction as part of the update clause here. I don't know the traffic exceptions for this but figure it will be under 10k records per day. Is this the best way to handle this scenario? If so, are there any details that I've left out, such as a hint here or there? Thanks! Dave

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• Cannot use READPAST in snapshot isolation mode

  - by Marcus

  I have a process which is called from multiple threads which does the following: Start transaction Select unit of work from work table with by finding the next row where IsProcessed=0 with hints (UPDLOCK, HOLDLOCK, READPAST) Process the unit of work (C# and SQL stored procedures) Commit the transaction The idea of this is that a thread dips into the pool for the "next" piece of work, and processes it, and the locks are there to ensure that a single piece of work is not processed twice. (the order doesn't matter). All this has been working fine for months. Until today that is, when I happened to realise that despite enabling snapshot isolation and making it the default at the database level, the actual transaction creation code was manually setting an isolation level of "ReadCommitted". I duly changed that to "Snapshot", and of course immediately received the "You can only specify the READPAST lock in the READ COMMITTED or REPEATABLE READ" error message. Oops! The main reason for locking the row was to "mark the row" in such a way that the "mark" would be removed when the transaction that applied the mark was committed and the lock seemed to be the best way to do this, since this table isn't read otherwise except by these threads. If I were to use the IsProcessed flag as the lock, then presumably I would need to do the update first, and then select the row I just updated, but I would need to employ the NOLOCK flag to know whether any other thread had set the flag on a row. All sounds a bit messy. The easiest option would be to abandon the snapshot isolation mode altogether, but the design of step #3 requires it. Any bright ideas on the best way to resolve this problem? Thanks Marcus

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• pointer being freed was not allocated. Complex malloc history help

  - by Martin KS

  I've followed the guides helpfully linked here: http://stackoverflow.com/questions/295778/iphone-debugging-pointer-being-freed-was-not-allocated-errors but the malloc_history is really throwing me for a loop, can anyone shed any light on the following: ALLOC 0x185c600-0x18605ff [size=16384]: thread_a068a4e0 |start | main | UIApplicationMain | -[UIApplication _run] | CFRunLoopRunInMode | CFRunLoopRunSpecific | PurpleEventCallback | _UIApplicationHandleEvent | -[UIApplication sendEvent:] | -[UIApplication handleEvent:withNewEvent:] | -[UIApplication _reportAppLaunchFinished] | CA::Transaction::commit() | CA::Context::commit_transaction(CA::Transaction*) | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CA::Context::commit_layer(_CALayer*, unsigned int, unsigned int, void*) | CA::Render::encode_set_object(CA::Render::Encoder*, unsigned long, unsigned int, CA::Render::Object*, unsigned int) | CA::Render::Layer::encode(CA::Render::Encoder*) const | CA::Render::Image::encode(CA::Render::Encoder*) const | CA::Render::Encoder::encode_data_async(void const*, unsigned long, void (*)(void const*, void*), void*) | CA::Render::Encoder::encode_bytes(void const*, unsigned long) | CA::Render::Encoder::grow(unsigned long) | realloc | malloc_zone_realloc ---- FREE 0x185c600-0x18605ff [size=16384]: thread_a068a4e0 |start | main | UIApplicationMain | -[UIApplication _run] | CFRunLoopRunInMode | CFRunLoopRunSpecific | PurpleEventCallback | _UIApplicationHandleEvent | -[UIApplication sendEvent:] | -[UIApplication handleEvent:withNewEvent:] | -[UIApplication _reportAppLaunchFinished] | CA::Transaction::commit() | CA::Context::commit_transaction(CA::Transaction*) | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CALayerCommitIfNeeded | CA::Context::commit_layer(_CALayer*, unsigned int, unsigned int, void*) | CA::Render::encode_set_object(CA::Render::Encoder*, unsigned long, unsigned int, CA::Render::Object*, unsigned int) | CA::Render::Layer::encode(CA::Render::Encoder*) const | CA::Render::Image::encode(CA::Render::Encoder*) const | CA::Render::Encoder::encode_data_async(void const*, unsigned long, void (*)(void const*, void*), void*) | CA::Render::Encoder::encode_bytes(void const*, unsigned long) | CA::Render::Encoder::grow(unsigned long) | realloc | malloc_zone_realloc ALLOC 0x185e000-0x185e62f [size=1584]: thread_a068a4e0 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __NSFireDelayedPerform | -[UITableView _userSelectRowAtIndexPath:] | -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] | -[PLAlbumView tableView:didSelectRowAtIndexPath:] | -[PLUIAlbumViewController albumView:selectedPhoto:] | PLNotifyImagePickerOfImageAvailability | -[UIImagePickerController _imagePickerDidCompleteWithInfo:] | -[GalleryViewController imagePickerController:didFinishPickingMediaWithInfo:] | UIImageJPEGRepresentation | CGImageDestinationFinalize | _CGImagePluginWriteJPEG | writeOne | _cg_jpeg_start_compress | _cg_jinit_compress_master | _cg_jinit_c_prep_controller | alloc_sarray | alloc_large | malloc | malloc_zone_malloc ---- FREE 0x185e000-0x185e62f [size=1584]: thread_a068a4e0 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __NSFireDelayedPerform | -[UITableView _userSelectRowAtIndexPath:] | -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] | -[PL AlbumView tableView:didSelectRowAtIndexPath:] | -[PLUIAlbumViewController albumView:selectedPhoto:] | PLNotifyImagePickerOfImageAvailability | -[UIImagePickerController _imagePickerDidCompleteWithInfo:] | -[GalleryViewController imagePickerController:didFinishPickingMediaWithInfo:] | UIImageJPEGRepresentation | CGImageDestinationFinalize | _CGImagePluginWriteJPEG | writeOne | _cg_jpeg_abort | free_pool | free ALLOC 0x185c800-0x185ea1f [size=8736]: thread_a068a4e0 |start | main | UIApplicationMain | GSEventRun | GSEventRunModal | CFRunLoopRunInMode | CFRunLoopRunSpecific | __NSFireDelayedPerform | -[UITableView _userSelectRowAtIndexPath:] | -[UITableView _selectRowAtIndexPath:animated:scrollPosition:notifyDelegate:] | -[PLAlbumView tableView:didSelectRowAtIndexPath:] | -[PLUIAlbumViewController albumView:selectedPhoto:] | PLNotifyImagePickerOfImageAvailability | -[UIImagePickerController _imagePickerDidCompleteWithInfo:] | -[GalleryViewController imagePickerController:didFinishPickingMediaWithInfo:] | -[UIImage initWithData:] | _UIImageRefFromData | CGImageSourceCreateImageAtIndex | makeImagePlus | _CGImagePluginInitJPEG | initImageJPEG | calloc | malloc_zone_calloc

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• Spikes in Socket Performance

  - by Harun Prasad

  We are facing random spikes in high throughput transaction processing system using sockets for IPC. Below is the setup used for the run: The client opens and closes new connection for every transaction, and there are 4 exchanges between the server and the client. We have disabled the TIME_WAIT, by setting the socket linger (SO_LINGER) option via getsockopt as we thought that the spikes were caused due to the sockets waiting in TIME_WAIT. There is no processing done for the transaction. Only messages are passed. OS used Centos 5.4 The average round trip time is around 3 milli seconds, but some times the round trip time ranges from 100 milli seconds to couple of seconds. Steps used for Execution and Measurement and output Starting the server $ python sockServerLinger.py /dev/null & Starting the client to post 1 million transactions to the server. And logs the time for a transaction in the client.log file. $ python sockClient.py 1000000 client.log Once the execution finishes the following command will show the execution time greater than 100 milliseconds in the format <line_number>:<execution_time>. $ grep -n "0.[1-9]" client.log | less Below is the example code for Server and Client. Server # File: sockServerLinger.py import socket, traceback,time import struct host = '' port = 9999 l_onoff = 1 l_linger = 0 lingeropt = struct.pack('ii', l_onoff, l_linger) s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) s.setsockopt(socket.SOL_SOCKET, socket.SO_REUSEADDR, 1) s.setsockopt(socket.SOL_SOCKET, socket.SO_LINGER, lingeropt) s.bind((host, port)) s.listen(1) while 1: try: clientsock, clientaddr = s.accept() print "Got connection from", clientsock.getpeername() data = clientsock.recv(1024*1024*10) #print "asdasd",data numsent=clientsock.send(data) data1 = clientsock.recv(1024*1024*10) numsent=clientsock.send(data) ret = 1 while(ret>0): data1 = clientsock.recv(1024*1024*10) ret = len(data) clientsock.close() except KeyboardInterrupt: raise except: print traceback.print_exc() continue Client # File: sockClient.py import socket, traceback,sys import time i = 0 while 1: try: st = time.time() s = socket.socket(socket.AF_INET,socket.SOCK_STREAM) while (s.connect_ex(('127.0.0.1',9999)) != 0): continue numsent=s.send("asd"*1000) response = s.recv(6000) numsent=s.send("asd"*1000) response = s.recv(6000) i+=1 if i == int(sys.argv[1]): break except KeyboardInterrupt: raise except: print "in exec:::::::::::::",traceback.print_exc() continue print time.time() -st

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• How to explain to users the advantages of dumb primary key?

  - by Hao

  Primary key attractiveness I have a boss(and also users) that wants primary key to be sophisticated/smart/attractive control number(sort of like Social Security number, or credit card number format) I just padded the primary key(in Views) with zeroes to appease their desire to make the control number sophisticated,smart and attractive. But they wanted it as: first 2 digits as client code, then 4 digits as year year, then last 4 digits as transaction number on that client on a given year, then reset the transaction number of client to 1 when next year flows. Each client's transaction starts with 1. e.g. WM20090001, WM20090002, BB2009001, WM20100001, BB20100001 But as I wanted to make things as simple as possible, I forgo embedding their suggested smartness in primary key, I just keep the primary key auto increments regardless of client and year. But to make it not dull-looking(they really are adamant to make the primary key as smart control number), I made the primary key appears to them smart, on view query, I put the client code and four digit year code on front of the eight-zero padded autoincrement key, i.e. WM200900000001. Sort of slug-like information on autoincremented primary key. Keeping primary key autoincrement regardless of any other information, we are able keep other potential side effects problem when they edit a record, for example, if they made a mistake of entering the transaction on WM, then they edit the client code to BB, if we use smart primary key, the primary keys of WM customer will have gaps in their control number. Or worse yet, instead of letting the control numbers have gaps/holes, the user will request that subsequent records of that gap should shift up to that gap and have their subsequent primary keys re-adjust(decremented). How do you deal with these user requests(reasonable or otherwise)? Do you yield to their request? Or just continue using dumb primary key and explain them the repercussions of having a very smart/sophisticated primary key and educate them the significant advantages of having a dumb primary key? P.S. quotable quote(http://articles.techrepublic.com.com/5100-10878_11-1044961.html): "If you hold your tongue the first time users ask what is for them a reasonable request, things will work a lot better in the end."

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• Nature of Lock is child table while deletion(sql server)

  - by Mubashar Ahmad

  Dear Devs From couple of days i am thinking of a following scenario Consider I have 2 tables with parent child relationship of kind one-to-many. On removal of parent row i have to delete the rows in child those are related to parents. simple right? i have to make a transaction scope to do above operation i can do this as following; (its psuedo code but i am doing this in c# code using odbc connection and database is sql server) begin transaction(read committed) Read all child where child.fk = p1 foreach(child) delete child where child.pk = cx delete parent where parent.pk = p1 commit trans OR begin transaction(read committed) delete all child where child.fk = p1 delete parent where parent.pk = p1 commit trans Now there are couple of questions in my mind Which one of above is better to use specially considering a scenario of real time system where thousands of other operations(select/update/delete/insert) are being performed within a span of seconds. does it ensure that no new child with child.fk = p1 will be added until transaction completes? If yes for 2nd question then how it ensures? do it take the table level locks or what. Is there any kind of Index locking supported by sql server if yes what it does and how it can be used. Regards Mubashar

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• mnesia primary key

  - by maryjanne

  Hi I have two tables one notes and one tag and I want to make the id from notes primary key to use it in the tag table, but I don't know where I do wrong. My notes id is generate from another table counter, with the function dirty_update_counter. My function for the id_notes from tag looks like this: Fun = fun() -> mnesia:write(#tag{ id_note =0}) end, mnesia:transaction(Fun). generate_Oid(TableName) when is_atom(TableName) -> F = fun() -> [Oid] = mnesia:read(tag, TableName, write), NewId = Oid#tag.id_note+1, New = Oid#tag{id_note = NewId}, mnesia:write(New), NewId end, mnesia:transaction(F). insert_n(N) when is_record(N, note) -> F = fun() -> {atomic, Id} = generate_Oid(note), New = N#note{id = Id}, mnesia:write(New), New end, mnesia:transaction(F). find_n(Id) when is_integer(Id) -> {atomic, [N]} = mnesia:transaction(fun() -> mnesia:read({note, Id}) end), N. But this function don't increment my field id_note from the table tag, despite the fact that in my note table, my id field is incremented from counter table. Thanks in advance for any help.

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• Guice, JDBC and managing database connections

  - by pledge

  I'm looking to create a sample project while learning Guice which uses JDBC to read/write to a SQL database. However, after years of using Spring and letting it abstract away connection handling and transactions I'm struggling to work it our conceptually. I'd like to have a service which starts and stops a transaction and calls numerous repositories which reuse the same connection and participate in the same transaction. My questions are: Where do I create my Datasource? How do I give the repositories access to the connection? (ThreadLocal?) Best way to manage the transaction (Creating an Interceptor for an annotation?) The code below shows how I would do this in Spring. The JdbcOperations injected into each repository would have access to the connection associated with the active transaction. I haven't been able to find many tutorials which cover this, beyond ones which show creating interceptors for transactions. I am happy with continuing to use Spring as it is working very well in my projects, but I'd like to know how to do this in pure Guice and JBBC (No JPA/Hibernate/Warp/Reusing Spring) @Service public class MyService implements MyInterface { @Autowired private RepositoryA repositoryA; @Autowired private RepositoryB repositoryB; @Autowired private RepositoryC repositoryC; @Override @Transactional public void doSomeWork() { this.repositoryA.someInsert(); this.repositoryB.someUpdate(); this.repositoryC.someSelect(); } } @Repository public class MyRepositoryA implements RepositoryA { @Autowired private JdbcOperations jdbcOperations; @Override public void someInsert() { //use jdbcOperations to perform an insert } } @Repository public class MyRepositoryB implements RepositoryB { @Autowired private JdbcOperations jdbcOperations; @Override public void someUpdate() { //use jdbcOperations to perform an update } } @Repository public class MyRepositoryC implements RepositoryC { @Autowired private JdbcOperations jdbcOperations; @Override public String someSelect() { //use jdbcOperations to perform a select and use a RowMapper to produce results return "select result"; } }

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• Lost Update Anomaly in Sql Server Update Command

  - by Javed

  Hi, I am very much confused. I have a transaction in ReadCommitted Isolation level. Among other things I am also updating a counter value in it, something similar to below: Update tblCount set counter = counter + 1 My application is a desktop application and this transaction happens to occur quite frequently and concurrently. We recently noticed an error that sometimes the counter value doesn't get updated or is missed. We also insert one record on each counter update so we are sure that records have been inserted but somehow counter fails to update. This happens once in 2000 simulaneous transactions. I seriously doubt it is a lost update anomaly I am facing but if you look at the command above, it's just update the counter from its own value: if I have started a transaction and the transaction has reached this statement, it should have locked the row. This should not cause lost update, but it's happening somehow. Is the thing that this update command works in two parts? Like first it reads the counter value (during which it doesn't get the exclusive lock) and then writes the new calculated value (when it does get an exclusive lock)? Please help, I have got really confused.

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• SqlBulkCopy causes Deadlock on SQL Server 2000.

  - by megatoast

  I have a customized data import executable in .NET 3.5 which the SqlBulkCopy to basically do faster inserts on large amounts of data. The app basically takes an input file, massages the data and bulk uploads it into a SQL Server 2000. It was written by a consultant who was building it with a SQL 2008 database environment. Would that env difference be causing this? SQL 2000 does have the bcp utility which is what BulkCopy is based on. So, When we ran this, it triggered a Deadlock error. Error details: Transaction (Process ID 58) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. I've tried numerous ways to try to resolve it. like temporarily setting the connection string variable MultipleActiveResultSets=true, which wasn't ideal, but it still gives a Deadlock error. I also made sure it wasn't a connection time out problem. here's the function. Any advice? /// <summary> /// Bulks the insert. /// </summary> public void BulkInsert(string destinationTableName, DataTable dataTable) { SqlBulkCopy bulkCopy; if (this.Transaction != null) { bulkCopy = new SqlBulkCopy ( this.Connection, SqlBulkCopyOptions.TableLock, this.Transaction ); } else { bulkCopy = new SqlBulkCopy ( this.Connection.ConnectionString, SqlBulkCopyOptions.TableLock | SqlBulkCopyOptions.UseInternalTransaction ); } bulkCopy.ColumnMappings.Add("FeeScheduleID", "FeeScheduleID"); bulkCopy.ColumnMappings.Add("ProcedureID", "ProcedureID"); bulkCopy.ColumnMappings.Add("AltCode", "AltCode"); bulkCopy.ColumnMappings.Add("AltDescription", "AltDescription"); bulkCopy.ColumnMappings.Add("Fee", "Fee"); bulkCopy.ColumnMappings.Add("Discount", "Discount"); bulkCopy.ColumnMappings.Add("Comment", "Comment"); bulkCopy.ColumnMappings.Add("Description", "Description"); bulkCopy.BatchSize = dataTable.Rows.Count; bulkCopy.DestinationTableName = destinationTableName; bulkCopy.WriteToServer(dataTable); bulkCopy = null; }

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• Locking a table for getting MAX in LINQ

  - by Hossein Margani

  Hi Every one! I have a query in LINQ, I want to get MAX of Code of my table and increase it and insert new record with new Code. just like the IDENTITY feature of SQL Server, but here my Code column is char(5) where can be alphabets and numeric. My problem is when inserting a new row, two concurrent processes get max and insert an equal Code to the record. my command is: var maxCode = db.Customers.Select(c=>c.Code).Max(); var anotherCustomer = db.Customers.Where(...).SingleOrDefault(); anotherCustomer.Code = GenerateNextCode(maxCode); db.SubmitChanges(); I ran this command cross 1000 threads and each updating 200 customers, and used a Transaction with IsolationLevel.Serializable, after two or three execution an error occured: using (var db = new DBModelDataContext()) { DbTransaction tran = null; try { db.Connection.Open(); tran = db.Connection.BeginTransaction(IsolationLevel.Serializable); db.Transaction = tran; . . . . tran.Commit(); } catch { tran.Rollback(); } finally { db.Connection.Close(); } } error: Transaction (Process ID 60) was deadlocked on lock resources with another process and has been chosen as the deadlock victim. Rerun the transaction. other IsolationLevels generates this error: Row not found or changed. Please help me, thank you.

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• MySQL return Deadlock with insert row and FK is locked 'for update'

  - by constantin-slednev

  Hello developers! I get deadlock error in my mysql transaction. The simple example of my situation: Thread1 > set autocommit=0; Query OK, 0 rows affected (0.00 sec) Thread1 > SET TRANSACTION ISOLATION LEVEL READ COMMITTED; Query OK, 0 rows affected (0.00 sec) Thread1 > SELECT * FROM A WHERE ID=1000 FOR UPDATE; 1 row in set (0.00 sec) Thread2 > set autocommit=0; Query OK, 0 rows affected (0.00 sec) Thread2 > SET TRANSACTION ISOLATION LEVEL READ COMMITTED; Query OK, 0 rows affected (0.00 sec) Thread2 > INSERT INTO B (AID, NAME) VALUES (1000, 'Hello world'); SLEEP Query OK, 1 row affected (4.99 sec) Thread1 > INSERT INTO B (AID, NAME) VALUES (1000, 'Hello world2'); ERROR 1213 (40001): Deadlock found when trying to get lock; try restarting transaction B.AID -> FK -> A.ID I see three solutions: catch deadlock error in code and retry query. use innodb_locks_unsafe_for_binlog in my.cnf lock (for update) table A in Thread2 before insert Can you give me more solutions ? Current solutions do not fit me.

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