我有以下实体：

@Entity
@Table(name = "product",
        indexes = {@Index(name = "productIndex", columnList = "family, group, type", unique = true)})
public class Product implements Serializable {

    @Id
    @Column(name = "id")
    private Long id;

    @Column(name = "family")
    private String family;

    @Column(name = "group")
    private String group;

    @Column(name = "type")
    private String type;

}

我尝试清空它的数据库表，并插入新行：

@Transactional
public void update(List<Product> products) {
    productRepository.deleteAll();
    productRepository.batchInsert(products);
}

ProductRepository为：

public interface ProductRepository extends JpaRepository<Product, Long>, BatchRepository<Product> { }

和BatchRepository：

@Repository
public class BatchRepository<T> {

    @PersistenceContext
    private EntityManager entityManager;

    @Override
    public int batchInsert(List<T> entities) {
        int count = 0;

        for (T entity : entities) {
            entityManager.persist(entity);
            count++;

            if (count % 2000 == 0) {
                entityManager.flush();
                entityManager.clear();
            }
        }

        entityManager.flush();
        entityManager.clear();

        return count;
    }

}

尝试执行java.sql.BatchUpdateException: ORA-00001: unique constraint (productIndex) violated的插入失败，但是前面的删除不应该使这种冲突不可能发生吗？