Hibernate乐观地锁定Postgres和MariaDb之间的不同行为 [英] Hibernate optimistic locking different behavior between Postgres and MariaDb

问题描述

我刚刚发现，当我对Postgresql或MariaDB数据库使用开放式锁定时，我的应用程序的行为会有所不同，我想知道是否有人可以解释会发生什么情况，以及如何使该应用程序与MariaDB一样工作?我将Postgresl 10.5和MariaDB 10.3.10与InnoDB引擎和默认设置一起使用.我使用的是Spring框架版本5.1.0和Hibernate 5.3.6.

I just discovered that my application behaves differently when I use optimistic locking with a Postgresql or a MariaDB database and I am wondering if somebody can explain what happens and how could I make the application work in the same way with MariaDB? I use Postgresl 10.5 and MariaDB 10.3.10 with InnoDB engine and default settings. I use Spring framework version 5.1.0 and Hibernate 5.3.6.

所以我的代码如下:

@Entity
@Getter
@Setter
@NoArgsConstructor
public class Bla {

    @Id
    @GeneratedValue
    private long id;

    @Version
    private long version;

    private int counter;
}

我还有一个用于该实体的存储库和以下服务方法:

I also have a repository for this entity and the following service method:

@Transactional
public int increment(long id) {
    Bla bla = blaRepo.getOne(id);
    bla.setCounter(bla.getCounter() + 1);
    return bla.getCounter();
}

如果我在多个线程上调用此方法，我希望如果它们接触具有相同版本的实体，则更新只会对其中一个执行成功.例如:如果我一次运行以Postgres db启动50个线程，则会获得3个成功调用并返回值1、2、3，而其他47个失败，并返回ObjectOptimisticLockingFailureException，这是预期的行为-这就是我想要的方式该应用程序的行为.

If I call this method on multiple threads I would expect update would succeed only for a single one of them if they touch the entity with the same version. As an example: if I start 50 thread with Postgres db in one run I get 3 calls that succeed and return the values 1, 2, 3 and the other 47 fail with an ObjectOptimisticLockingFailureException which is the expected behavior - this is how I would like the app to behave.

但是，如果我切换到MariaDB，则不会发生这种情况.这些线程中的所有50个均已成功完成，并且在多个线程中得到的响应值相同，就好像没有乐观锁一样.例如，现在前5个线程返回1，然后其中20个线程返回2，其余3个或4.

However, if I switch to MariaDB then this doesn't happen. All 50 of these threads are completed successfully and I get the same response value in multiple threads as if there would be no optimistic lock. For example now the first 5 threads returned 1, then 20 of them returned 2, and the rest 3 or 4.

为什么会这样?这没有任何意义-对于这两个数据库，生成的查询都是

Why this is happening? It doesn't make any sense - with both databases the query generated is

update bla set counter=?, version=? where id=? and version=?

但是在Postgresql中将正确失败，并且使用MariaDB将会意外成功.

But in Postgresql will fail correctly and with MariaDB will succeed unexpectedly.

推荐答案

我找到了解决此问题的方法.

I found the solution to this problem.

似乎我在application.properties中设置了此属性:

It seems that I had this property set in application.properties:

spring.jpa.properties.hibernate.jdbc.batch_size = 50

当我使用Postgresql时，我得到了带有两个线程的以下调试跟踪:

When I do use Postgresql I get the following debug trace with two threads:

13223 [pool-2-thread-2] DEBUG org.hibernate.SQL - update bla set counter=?, version=? where id=? and version=?
13223 [pool-2-thread-1] DEBUG org.hibernate.SQL - update bla set counter=?, version=? where id=? and version=? 
13226 [pool-1-thread-1] DEBUG org.hibernate.engine.jdbc.batch.internal.BatchingBatch - Executing batch size: 1
13226 [pool-1-thread-2] DEBUG org.hibernate.engine.jdbc.batch.internal.BatchingBatch - Executing batch size: 1
13230 [pool-1-thread-1] ERROR org.hibernate.engine.jdbc.batch.internal.BatchingBatch - HHH000315: Exception executing batch [org.hibernate.StaleStateException: Batch update returned unexpected row count from update [0]; actual row count: 0; expected: 1], SQL: update bla set counter=?, version=? where id=? and version=?

，然后使用具有相同批处理大小50的MariaDB:

and then with MariaDB with the same batch size 50:

21978 [pool-2-thread-2] DEBUG org.hibernate.SQL - update bla set counter=?, version=? where id=? and version=?
21978 [pool-2-thread-1] DEBUG org.hibernate.SQL - update bla set counter=?, version=? where id=? and version=? 
21979 [pool-2-thread-2] DEBUG org.hibernate.engine.jdbc.batch.internal.BatchingBatch - Executing batch size: 1
21979 [pool-2-thread-1] DEBUG org.hibernate.engine.jdbc.batch.internal.BatchingBatch - Executing batch size: 1
21980 [pool-2-thread-2] DEBUG org.hibernate.jdbc.Expectations - Success of batch update unknown: 0
21980 [pool-2-thread-1] DEBUG org.hibernate.jdbc.Expectations - Success of batch update unknown: 0

，然后使用批处理大小为1的MariaDB:

and then with MariaDB with batch size 1:

12994 [pool-2-thread-2] DEBUG org.hibernate.SQL - update bla set counter=?, version=? where id=? and version=?
12994 [pool-2-thread-1] DEBUG org.hibernate.SQL - update bla set counter=?, version=? where id=? and version=?
12997 [pool-2-thread-1] DEBUG org.hibernate.cache.internal.TimestampsCacheEnabledImpl - Invalidating space [bla], timestamp: 6307671153053696
12998 [pool-2-thread-2] DEBUG org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl - JDBC transaction marked for rollback-only (exception provided for stack trace)

现在应用程序确实抛出了预期的ObjectOptimisticLockingFailureException

And now indeed the application throw the expected ObjectOptimisticLockingFailureException

但是不幸的是，这意味着无法将MariaDb与乐观锁在实体上使用，并且任何批量大小大于1的对象都不兼容.

But unfortunately this means that using MariaDb with optimistic locking on entities and any batch size greater than 1 is not compatible.

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