我有一个EclipseLink JPA演示应用程序，它在执行一个JPQL UPDATE语句后发出一个JPQL SELECT语句。SELECT语句“看到”陈旧数据，如下所示:

• 如果未提供提示，则结果数据已过时
• 如果使用 .setHint（“javax.persistence.cache.storeMode”， “REFRESH”），则检索更新的数据
• 如果检索 .setHint（“javax.persistence.cache.retrieveMode”， “BYPASS”） 过时数据
• 如果我在查询之前执行 em.clear（），查询将检索更新的值（但这很明显，我想知道当持久性上下文未清除时会发生什么）。但是，这指向 1 级缓存问题。

我不明白 JPQL SELECT 从哪里获取过时的数据。它们显然不在共享缓存中（通过使用缓存接口的 BYPASS 提示和 contains（） 方法确认）。

我做的实验：

< li >将where 1=1添加到陈旧检索查询中，以检查是否发生了某些查询代码缓存(无变化) < li >从第二个SELECT查询中删除提示，以检查可能延迟的数据库提交是否存在时间问题(第二个查询也会发现陈旧数据)。

知道吗？

    package examples.client;
    
    import examples.model.Employee;
    import java.util.List;
    
    import javax.persistence.EntityManager;
    import javax.persistence.EntityManagerFactory;
    import javax.persistence.Persistence;
    
    public class EmployeeUPDATEModification {
    
        public static void main(String[] args) {
            EntityManagerFactory emf = Persistence.createEntityManagerFactory("EmployeeService");
            EntityManager em = emf.createEntityManager();
    
            System.out.println("***INITIAL SALARY VALUES\n");
            List<Employee> initial = em.createQuery("SELECT e FROM Employee e", Employee.class).getResultList();
            for (Employee e : initial) {
                System.out.println(e.getSalary());
            }
            System.out.println("***TESTING BULK UPDATE\n");
            em.getTransaction().begin();
            em.createQuery("UPDATE Employee e SET e.salary = e.salary*2").executeUpdate();
            em.getTransaction().commit();
    
            System.out.println("***SALARY VALUES AFTER BULK UPDATE FROM INITIAL LIST\n");
            for (Employee e : initial) {
                System.out.println(e.getSalary());
            }
    
            System.out.println("\n***PRINTING THE SALARY FROM A QUERY WITHOUT HINT \n");
            List<Employee> result = em.createQuery("SELECT e FROM Employee e", Employee.class).getResultList();
            for (Employee e : result) {
                System.out.println(e.getSalary());
            }
    
            System.out.println("\n***CHECKING THE SHARED CACHE\n");
            for (Employee e : result) {
                System.out.println(emf.getCache().contains(Employee.class, e.getId()) ? e + " is in shared chache"
                        : e + " is NOT in shared cache");
            }
    
            System.out.println("\n***PRINTING THE SALARY FROM A QUERY WITH HINT \n");
            List<Employee> result3 = em.createQuery("SELECT e FROM Employee e", Employee.class)
                    .setHint("javax.persistence.cache.storeMode", "REFRESH").getResultList();
            for (Employee e : result3) {
                System.out.println(e.getSalary());
            }
    
            // close the EM and EMF when done
            em.close();
            emf.close();
    
        }
    }

控制台

***INITIAL SALARY VALUES

[EL Fine]: sql: 2020-10-20 17:21:25.213--ServerSession(2092769598)--Connection(110651474)--Thread(Thread[main,5,main])--SELECT ID, NAME, SALARY FROM EMPLOYEE

100
200
300

***TESTING BULK UPDATE

[EL Fine]: sql: 2020-10-20 17:21:25.241--ClientSession(706665172)--Connection(110651474)--Thread(Thread[main,5,main])--UPDATE EMPLOYEE SET SALARY = (SALARY * ?)
    bind => [2]

***SALARY VALUES AFTER BULK UPDATE FROM INITIAL LIST

100
200
300

***PRINTING THE SALARY FROM A QUERY WITHOUT HINT 

[EL Fine]: sql: 2020-10-20 17:21:25.256--ServerSession(2092769598)--Connection(110651474)--Thread(Thread[main,5,main])--SELECT ID, NAME, SALARY FROM EMPLOYEE

100
200
300

***CHECKING THE SHARED CACHE

Employee id: 1 name: Piero salary: 100 is NOT in shared cache

Employee id: 2 name: Aldo salary: 200 is NOT in shared cache

Employee id: 3 name: Mario salary: 300 is NOT in shared cache

***PRINTING THE SALARY FROM A QUERY WITH HINT 

[EL Fine]: sql: 2020-10-20 17:21:25.271--ServerSession(2092769598)--Connection(110651474)--Thread(Thread[main,5,main])--SELECT ID, NAME, SALARY FROM EMPLOYEE

200
400
600

具有最佳日志记录级别的控制台

***PRINTING THE SALARY FROM A QUERY WITHOUT HINT 

[EL Finest]: query: 2020-10-20 18:14:08.097--UnitOfWork(955611965)--Thread(Thread[main,5,main])--Execute query ReadAllQuery(referenceClass=Employee sql="SELECT ID, NAME, SALARY FROM EMPLOYEE")

[EL Finest]: connection: 2020-10-20 18:14:08.097--ServerSession(1006485584)--Connection(1482246673)--Thread(Thread[main,5,main])--Connection acquired from connection pool [default].

[EL Fine]: sql: 2020-10-20 18:14:08.097--ServerSession(1006485584)--Connection(1482246673)--Thread(Thread[main,5,main])--SELECT ID, NAME, SALARY FROM EMPLOYEE

[EL Finest]: connection: 2020-10-20 18:14:08.099--ServerSession(1006485584)--Connection(1482246673)--Thread(Thread[main,5,main])--Connection released to connection pool [default].

400
800
1200

PRINTING THE SALARY FROM A QUERY WITH HINT 

***

[EL Finest]: query: 2020-10-20 18:14:08.119--UnitOfWork(955611965)--Thread(Thread[main,5,main])--Execute query ReadAllQuery(referenceClass=Employee sql="SELECT ID, NAME, SALARY FROM EMPLOYEE")

[EL Finest]: connection: 2020-10-20 18:14:08.119--ServerSession(1006485584)--Connection(1482246673)--Thread(Thread[main,5,main])--Connection acquired from connection pool [default].

[EL Fine]: sql: 2020-10-20 18:14:08.119--ServerSession(1006485584)--Connection(1482246673)--Thread(Thread[main,5,main])--SELECT ID, NAME, SALARY FROM EMPLOYEE

[EL Finest]: connection: 2020-10-20 18:14:08.121--ServerSession(1006485584)--Connection(1482246673)--Thread(Thread[main,5,main])--Connection released to connection pool [default].

[EL Finest]: transaction: 2020-10-20 18:14:08.122--UnitOfWork(955611965)--Thread(Thread[main,5,main])--Merge clone Employee id: 1 name: Piero salary: 800 

[EL Finest]: transaction: 2020-10-20 18:14:08.122--UnitOfWork(955611965)--Thread(Thread[main,5,main])--Merge clone Employee id: 2 name: Aldo salary: 1600 

[EL Finest]: transaction: 2020-10-20 18:14:08.123--UnitOfWork(955611965)--Thread(Thread[main,5,main])--Merge clone Employee id: 3 name: Mario salary: 2400 

800
1600
2400