在 H2 中切换同一事务中的两个唯一字段时违反唯一约束

Question

I have a Spring Boot application using Spring Data repositories with entities mapped with JPA. The database is H2. The table is auto-generated. I'm doing two updates in the same transaction. Each of them would on its own would violate a unique constraint, but when both are applied together, the result should be fine. However, I'm still getting an exception.

I tried to do the same update with a DB tool (Database view in IntelliJ IDEA) to try to see if that would work, getting this error:

Unexpected update count received (Actual: 0, Expected: 1). All changes will be rolled back.

This is my entity in question:

@Entity
@Table(
        name = "DATA_SET_COLUMN",
        uniqueConstraints = {
                @UniqueConstraint(columnNames = {"DATA_SET_ID", "ORDER_INDEX"})
        }
)
@Data
@EqualsAndHashCode(callSuper=true)
@NoArgsConstructor
@ToString(exclude = {"dataSet", "elements"})
public class DataSetColumn extends UniteFlowEntity {
    @Column(name = "ORDER_INDEX", nullable = false)
    private int order;

    @Column(name = "DATA_SET_ID", nullable = false)
    private String dataSetId;

    @ManyToOne(fetch= FetchType.LAZY)
    @JoinColumn(name="DATA_SET_ID", nullable = false, insertable = false, updatable = false)
    @JsonIgnore
    private DataSet dataSet;

    @OneToMany(mappedBy = "column", cascade = CascadeType.ALL, fetch = FetchType.LAZY)
    @JsonIgnore
    List<DataSetElement> elements;
}

Note the unique constraint on DATA_SET_ID and ORDER_INDEX .

I'm using a Spring Data repository for access:

@Repository
public interface DataSetColumnRepository extends JpaRepository<DataSetColumn, String> {}

Saving the entities looks something like this:

        repository.save(entity1);
        repository.save(entity2);

I have two DataSetColumns stored with the same DATA_SET_ID and want to switch the ORDER_INDEX (the one which has 0 gets 1 and vice versa). This happens in the same transaction (managed by Spring, as set up by Spring Boot).

My expectation was that the unique constraint would not be violated since after both updates the table should be valid. However, I'm getting this:

update unitelabs.data_set_column set creation_date=?, modification_date=?, data_set_id=?, order_index=? where id=? [23505-197]
    at org.h2.message.DbException.getJdbcSQLException(DbException.java:357)
    at org.h2.message.DbException.get(DbException.java:179)
    at org.h2.message.DbException.get(DbException.java:155)
    at org.h2.index.BaseIndex.getDuplicateKeyException(BaseIndex.java:101)
    at org.h2.mvstore.db.MVSecondaryIndex.requireUnique(MVSecondaryIndex.java:236)
    at org.h2.mvstore.db.MVSecondaryIndex.add(MVSecondaryIndex.java:202)
    at org.h2.mvstore.db.MVTable.addRow(MVTable.java:732)
    at org.h2.table.Table.updateRows(Table.java:509)
    at org.h2.command.dml.Update.update(Update.java:177)
    at org.h2.command.CommandContainer.update(CommandContainer.java:102)
    at org.h2.command.Command.executeUpdate(Command.java:261)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdateInternal(JdbcPreparedStatement.java:199)
    at org.h2.jdbc.JdbcPreparedStatement.executeUpdate(JdbcPreparedStatement.java:153)
    at com.zaxxer.hikari.pool.ProxyPreparedStatement.executeUpdate(ProxyPreparedStatement.java:61)
    at com.zaxxer.hikari.pool.HikariProxyPreparedStatement.executeUpdate(HikariProxyPreparedStatement.java)
    at org.hibernate.engine.jdbc.internal.ResultSetReturnImpl.executeUpdate(ResultSetReturnImpl.java:175)
    at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3356)
    at org.hibernate.persister.entity.AbstractEntityPersister.updateOrInsert(AbstractEntityPersister.java:3229)
    at org.hibernate.persister.entity.AbstractEntityPersister.update(AbstractEntityPersister.java:3630)
    at org.hibernate.action.internal.EntityUpdateAction.execute(EntityUpdateAction.java:146)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:604)
    at org.hibernate.engine.spi.ActionQueue.executeActions(ActionQueue.java:478)
    at org.hibernate.event.internal.AbstractFlushingEventListener.performExecutions(AbstractFlushingEventListener.java:356)
    at org.hibernate.event.internal.DefaultFlushEventListener.onFlush(DefaultFlushEventListener.java:39)
    at org.hibernate.internal.SessionImpl.doFlush(SessionImpl.java:1454)
    at org.hibernate.internal.SessionImpl.managedFlush(SessionImpl.java:511)
    at org.hibernate.internal.SessionImpl.flushBeforeTransactionCompletion(SessionImpl.java:3283)
    at org.hibernate.internal.SessionImpl.beforeTransactionCompletion(SessionImpl.java:2479)
    at org.hibernate.engine.jdbc.internal.JdbcCoordinatorImpl.beforeTransactionCompletion(JdbcCoordinatorImpl.java:473)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.beforeCompletionCallback(JdbcResourceLocalTransactionCoordinatorImpl.java:178)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl.access$300(JdbcResourceLocalTransactionCoordinatorImpl.java:39)
    at org.hibernate.resource.transaction.backend.jdbc.internal.JdbcResourceLocalTransactionCoordinatorImpl$TransactionDriverControlImpl.commit(JdbcResourceLocalTransactionCoordinatorImpl.java:271)
    at org.hibernate.engine.transaction.internal.TransactionImpl.commit(TransactionImpl.java:98)
    at org.springframework.orm.jpa.JpaTransactionManager.doCommit(JpaTransactionManager.java:532)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.processCommit(AbstractPlatformTransactionManager.java:746)
    at org.springframework.transaction.support.AbstractPlatformTransactionManager.commit(AbstractPlatformTransactionManager.java:714)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.commitTransactionAfterReturning(TransactionAspectSupport.java:533)
    at org.springframework.transaction.interceptor.TransactionAspectSupport.invokeWithinTransaction(TransactionAspectSupport.java:304)
    at org.springframework.transaction.interceptor.TransactionInterceptor.invoke(TransactionInterceptor.java:98)
    at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:186)
    at org.springframework.aop.framework.CglibAopProxy$DynamicAdvisedInterceptor.intercept(CglibAopProxy.java:688)
    at uniteflow.dataset.api.rest.DataSetApi$$EnhancerBySpringCGLIB$$839b47f6.saveColumns(<generated>)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at java.base/jdk.internal.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at java.base/jdk.internal.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.base/java.lang.reflect.Method.invoke(Method.java:566)
    at org.springframework.web.method.support.InvocableHandlerMethod.doInvoke(InvocableHandlerMethod.java:189)
    at org.springframework.web.method.support.InvocableHandlerMethod.invokeForRequest(InvocableHandlerMethod.java:138)
    at org.springframework.web.servlet.mvc.method.annotation.ServletInvocableHandlerMethod.invokeAndHandle(ServletInvocableHandlerMethod.java:102)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.invokeHandlerMethod(RequestMappingHandlerAdapter.java:895)
    at org.springframework.web.servlet.mvc.method.annotation.RequestMappingHandlerAdapter.handleInternal(RequestMappingHandlerAdapter.java:800)
    at org.springframework.web.servlet.mvc.method.AbstractHandlerMethodAdapter.handle(AbstractHandlerMethodAdapter.java:87)
    at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:1038)
    at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:942)
    at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:1005)
    at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:908)

Is my expectation wrong and this doesn't work in principle? Or could there be something wrong in my code?

Answer 1

Your expectation is wrong, to allow such modification the unique constraint should be explicitly defined as deferred (in databases that support optional feature F721) and H2 currently (as of 1.4.199) does not support this feature, there is a feature request for it: https://github.com/h2database/h2database/issues/223

The typical workaround is to assign a some fake value to the first row, then change the second row to its new value and finally change the first row to its new value.