java - Hibernate 序列在更新期间不会为主键 id 生成连续的数字

Question

我有一个带有 spring 数据和 hibernate 的 spring boot 应用程序，用于将数据保存到 MySQL 数据库。我有一张用户表和一张地址表，它们之间的关系太多。当我保存数据时，自动生成的主键会正确生成，但是当我更新地址表(向用户添加第二个地址)时，为第二个用户生成的主键不连续。

这些是我的实体。

@Entity
@Table(name = "user")
public class User {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "user_generator")
    @SequenceGenerator(name="user_generator", sequenceName = "user_seq")
    @Column(name = "user_id")
    private Long id;
    @Unique
    @Column(nullable = false)
    private String username;
    @Column(nullable = false)
    private String firstname;
    @Column(nullable = false)
    private String lastname;
    private String password;

    @OneToMany(mappedBy = "user", fetch = FetchType.EAGER, cascade = CascadeType.ALL, orphanRemoval = true)
    private List<Address> address;
    private Boolean active;
    private String mobile;
    private String home;

    public User() {
    }

@Entity
@Table(name = "address")
public class Address {

    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "address_generator")
    @SequenceGenerator(name = "address_generator", sequenceName = "address_seq")
    @Column(name = "adress_id")
    private Long id;
    @Column(nullable = false)
    private String street1;
    private String street2;
    @Column(nullable = false)
    private String city;
    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumn(name = "user_id")
    private User user;

这是更新方法

   @Override
    public UserDTO updateUser(UserDTO userDto) {

          User user = userMapper.getUserEntity(userDto);
          user.getAddress().forEach(a->a.setUser(user));
          User updatedUser = userRepository.save(user);
          return userMapper.getUserDTO(updatedUser);
    }

这是我的有效负载。 id=2 的地址已保存，我添加了第二个地址。

    {
        "id": 2,
        "username": "test@gmail.com",
        "firstname": "lana",
        "lastname": "Lee",
        "address": [
            {
                "id": 2,
                "street1": "344",
                "street2": "abcd",
                "city": "mycity"
            },
            {
                 "street1": "7",
                "street2": "cde",
                "city": "mycity"
            }
        ],
        "active": false,
        "mobile": "1232211441"
    }

当我更新时，这就是地址表的 id 列的样子。新添加的地址是52，而不是5。

Answer 1

您必须根据 SequenceGenerator Javadoc 更改默认分配大小设置为:

allocationSize

public abstract int allocationSize (Optional)

amount to increment by when allocating sequence numbers from thesequence.

Default: 50

尝试将其设置为 1 或任何适合您需要的值。