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How to use Sprint transactional annotation

1. Attributes

• value and transactionManager
  • used to provide a TransactionManager reference to be used when handling the transaction for the annotated block
• propagation
  • define how the transaction boundaries propagate to other methods that will be called either directly or indirectly from within the annotated block
  • default is REQUIRED
    • means a transaction is started if no transaction is already available
    • otherwise use the current running thread
• timeout and timeoutString
  • define the max number of seconds the current method is allowed to run
• readOnly
  • defines if the current transaction is read-only or read-write
• rollbackFor and rollbackForClassName
  • define one or more Throwable classes for which the current transaction will be rolled back
  • default is RuntimeException or an Error is thrown, but not for a checked Exception
• noRollbackFor and noRollbackForClassName
  • used for one or more RuntimeException

2. Transaction Override

• addStatementReportOperation is using the serializeble level, which override the class level readonly transaction

@Service
@Transactional(readOnly = true)
public class OperationService {

    @Transactional(isolation = Isolation.SERIALIZABLE)
    public boolean addStatementReportOperation(
        String statementFileName,
        long statementFileSize,
        int statementChecksum,
        OperationType reportType) {

        ...
    }
}

• we use readOnly in class level because Spring could perform some read only optimization
  • we could save memory when loading read only entities since the loaded state is discarded right away, and not kept for the whole duration of the currently running persistence context
  • also, in the cluster, read only data source could be redirected to DB replica instead of DB primary, this could also reduce the burden for primary

1. https://stackoverflow.com/questions/10394857/how-to-use-transactional-with-spring-data#:~:text=Thus we recommend using %40Transactional,re-decorated in that interface
2. https://vladmihalcea.com/spring-read-only-transaction-hibernate-optimization/
3. https://vladmihalcea.com/spring-transactional-annotation/

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