transactions

问题 I have a Django 1.7 beta 1 project with a standard user signup form. Conceptually, it makes sense for the form validation to fail if the username is already taken. However, the form validation and the saving of the successfully created user model are separate steps, so there's a race condition where the validation can pass but the actual user.save() can fail with an IntegrityError . I'm unclear on what happens if both the form validation and the user.save() step are wrapped in the same

问题 I have a Django 1.7 beta 1 project with a standard user signup form. Conceptually, it makes sense for the form validation to fail if the username is already taken. However, the form validation and the saving of the successfully created user model are separate steps, so there's a race condition where the validation can pass but the actual user.save() can fail with an IntegrityError . I'm unclear on what happens if both the form validation and the user.save() step are wrapped in the same

问题 Heres what Im thinking. Do you see any issues with this workaround to emulate 2 phase commit when using something like MongoDB where each operation is atomic and there is no support for transactions outside of that? transaction_scope: read message from servicebus - UpdateCustomerAddress get customer aggregate from docdb, replay events where commited =1 call customer.updateAddress validates creates customer address updated event apply event event store as uncommitted events do optimistic

问题 Heres what Im thinking. Do you see any issues with this workaround to emulate 2 phase commit when using something like MongoDB where each operation is atomic and there is no support for transactions outside of that? transaction_scope: read message from servicebus - UpdateCustomerAddress get customer aggregate from docdb, replay events where commited =1 call customer.updateAddress validates creates customer address updated event apply event event store as uncommitted events do optimistic

问题 How will the transaction started in callSessionBean2() behave in the following scenario? Is it suspended? What happens if an exception is thrown in SessionBean2? SessionBean2 was setup with BEAN transaction management type because it does not communicate with any database, only with AD server via LDAP. I'm asking because I've been having issues in a production server some week after deployment that calls to SessionBean2 starts to hang, with transaction timeouts as the only error. I figured

问题 How will the transaction started in callSessionBean2() behave in the following scenario? Is it suspended? What happens if an exception is thrown in SessionBean2? SessionBean2 was setup with BEAN transaction management type because it does not communicate with any database, only with AD server via LDAP. I'm asking because I've been having issues in a production server some week after deployment that calls to SessionBean2 starts to hang, with transaction timeouts as the only error. I figured

问题 im in trouble with implemenetation of a service layer, i think i did not understand this concept very well. In a DAO implementation i can write all CRUD logic for a specific technology and entity (for example hibernate and User table), and in a service layer we use a DAO for all data operation for the entity in DAO (like getUser, loginUser, etc..) is this ok? If this is ok i have a simple question, can i handle database connection (or in case of hibernate, session and transaction) within

问题 We are trying to migrate an Intranet Web Application, developed in VB6, from Windows Server 2003 to Windows Server 2008 R2 and we are facing a problem with two phase commit transactions between Microsoft SQL Server 2008 and DB2 on Z/OS Mainframe. On Windows Server 2008 R2 with DB2 v9.7.500.702 Fixpack 8 (64 bit) installed, the VB6 component registered in a COM+ application, when trying to update in transaction one table on SQL Server and another table on DB2, returns this error: [IBM][CLI

问题 I can't get information of that simple question over the PostgreSQL documentation, over the Web or even here on StackOverflow... I must not unsertand something essential here. I am making a simple SELECT / UPDATE transaction in PostgreSQL: START TRANSACTION; SELECT "column" FROM "table" WHERE "criterion" = 'value' AND "activated" = true; UPDATE "table" SET "activated" = false WHERE "criterion" = 'value'; COMMIT Basically, I need to get the value of a column when its activated state is true

问题 I can't get information of that simple question over the PostgreSQL documentation, over the Web or even here on StackOverflow... I must not unsertand something essential here. I am making a simple SELECT / UPDATE transaction in PostgreSQL: START TRANSACTION; SELECT "column" FROM "table" WHERE "criterion" = 'value' AND "activated" = true; UPDATE "table" SET "activated" = false WHERE "criterion" = 'value'; COMMIT Basically, I need to get the value of a column when its activated state is true