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POTransaction isolation level REPEATABLE_READ using hibernate and jdbc
 

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  1. POTransaction isolation level REPEATABLE_READ using hibernate and jdbc
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    <p>I am trying to develop a demo to cement my understanding of the REPEATABLE_READ isolation level. I have tried demos using hibernate and jdbc. JDBC works as expected, however hibernate does not.</p> <p>My expectation is that, if i read a database row within one session, and i try to write the same row from another session, it should block until the first session finishes.</p> <p><strong>Hibernate</strong>:- When i 'get' an object (row) in Thread 0 and sleep, and within Thread 1 we try to update the same object (row), Thread 1 should wait till Thread 0 commits.</p> <pre><code>class HibernateExample7_IsolationRR_Read_Write_Thread implements Runnable { private static final Logger logger = LoggerFactory.getLogger(HibernateExample7_IsolationRR_Read_Write_Thread.class); SessionFactory sessionFactory; int sleep; int newnumberplate; public HibernateExample7_IsolationRR_Read_Write_Thread(SessionFactory sessionFactory, int sleep, int newnumberplate) { this.sessionFactory = sessionFactory; this.sleep = sleep; this.newnumberplate = newnumberplate; } public void run() { Session session = sessionFactory.openSession(); Transaction tx = session.beginTransaction(); logger.info("TRYING TO GET VEHICLE 1"); Vehicle vid1 = (Vehicle) session.get(Vehicle.class, Integer.valueOf(1)); logger.info("GOT VEHICLE 1"); vid1.setNumberplate(this.newnumberplate); logger.info("SET NUMBERPLATE FOR 1"); try { Thread.sleep(sleep); } catch (InterruptedException e) { e.printStackTrace(); } tx.commit(); session.close(); logger.info("COMMITED"); } } </code></pre> <p>hibernate.connection.url is <strong>jdbc:derby:isolation;create=true</strong> and hibernate.connection.isolation is <strong>2</strong>. I make two objects of HibernateExample7_IsolationRR_Thread, and i create a scenario where Thread 0 gets the vehicle and sleeps for long time. Meanwhile Thread 1 tries to get and update Vehicle. It successfully commits even before Thread 0 commits.</p> <p>Due to the REPEATABLE_READ isolation level, shouldn't T1 wait on a commit. If not then it's a READ_COMMITED isolation level not a REPEATABLE_READ isolation level.</p>
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    1. USnev.m
    1. USnev.m
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    1. COWhat version if hsqldb are you using?
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      1. USsharakan
    2. COhsqldb version 2.2.8
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      1. USnev.m
 

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