PostreSQL不支持这一点。如果你做了一个外部SELECT，没有什么可以阻止某人插入一行到LEFT JOINED表中，从而修改你正在查看的结果集（例如，在重复读取时，列将不再是NULL）。
有关详细说明，请参见here

这是一个很长一段时间以来的问题，但我有一个类似的问题，希望我的答案将帮助别人。
假设我们有这个JPA实体：

@Entity
@Table(name = "card_transactions")
public class CardTransactionsEntity {
    @Id
    @GeneratedValue(strategy = GenerationType.SEQUENCE, generator = "card_trans_seq")
    @SequenceGenerator(name = "card_trans_seq", sequenceName = "card_trans_seq")
    private Long id;

    @ManyToOne(fetch = FetchType.LAZY)
    @JoinColumns({
            @JoinColumn(name = "ofd_id", referencedColumnName = "ofd_id"),
            @JoinColumn(name = "receipt_id", referencedColumnName = "receipt_id")})
    private ReceiptsEntity receipt;

    @Column
    @Enumerated(EnumType.STRING)
    private CardTransactionStatus requestStatus;

    ...

}

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我们希望选择CardTransactionsEntity with fetched ReceivtsEntity用于仅悲观更新CardTransactionsEntity。这可以使用Hibernate和Spring Data JPA存储库来完成，

public interface CardTransactionRepository extends JpaRepository<CardTransactionsEntity, Long> {

    @Query("select ct from CardTransactionsEntity ct left join fetch ct.receipt r where ct.requestStatus = :requestStatus")
    @Lock(value = LockModeType.PESSIMISTIC_WRITE)
    @QueryHints(value = {
            @QueryHint(name = "javax.persistence.lock.timeout", value = "-2"), // LockOptions.SKIP_LOCKED
            @QueryHint(name = "org.hibernate.lockMode.r", value = "NONE") // "r" is alias for ct.receipt and will excluded from PESSIMISTIC_WRITE
    })
    List<CardTransactionsEntity> loadCardTransactions(@Param("requestStatus") CardTransactionStatus requestStatus, Pageable pageable);

}

型
此存储库方法将执行查询，如

SELECT ct.*, r.* from card_transactions ct LEFT OUTER JOIN receipts r ON ct.ofd_id = r.ofd_id and ct.receipt_id = r.receipt_id WHERE ct.request_status=? LIMIT ? FOR UPDATE OF ct SKIP LOCKED

型

使用FetchType. LAZY连接表可以绕过此错误。此提取类型是默认类型，不需要为@OneToMany连接指定。

public class A{
   @Id
   private Long id;

   @OneToMany
   private Set<B> bSet;

   @OneToMany
   private Set<C> cSet;
}

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老问题，但我的用例描述可能对某人有帮助。
我在同一个查询中有很多表的连接+ @ passiotyGraph来获取一些东西。但只需要在一个主表中PESIMISTIC_passiotyGraph。
早期提出的从锁中排除表的解决方案很麻烦（大量的排除），在@ MyrtyGraph的情况下还有未知的别名。
因此，我们可以通过只提供@QueryHints来指定锁的确切表（而不是整个层次结构）：

//@Lock(LockModeType.PESSIMISTIC_WRITE) is inappropriate because it locks the whole hierarchy.
    @QueryHints(value = {
            @QueryHint(name = "org.hibernate.lockMode.ms", value = "PESSIMISTIC_WRITE") // "ms" is alias for MeasurementSet and will only be used in PESSIMISTIC_WRITE
    })

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但即使在这种情况下，Hibernate中也存在一个错误。来自HQL的别名会被来自@ MyrtyGraph的隐式别名干扰。
解决方案：摆脱@ MyrtyGraph，只通过HQL获取所有内容。

@QueryHints(value = {
            @QueryHint(name = "org.hibernate.lockMode.ms", value = "PESSIMISTIC_WRITE") // "ms" is alias for MeasurementSet and will only be used in PESSIMISTIC_WRITE
    })
    @Query("SELECT ms from MeasurementSet ms "
            + "INNER JOIN ms.measurementSetGroup msg "
            + "LEFT JOIN FETCH ms.pomSections ps LEFT JOIN FETCH ps.pointsOfMeasure pom LEFT JOIN FETCH pom.pomMeasurements "
            + "LEFT JOIN FETCH ms.prototypeMilestones "
            + "WHERE ms.id = :id and msg.modelNumber = :modelNumber")
    Optional<MeasurementSet> findEagerlyByIdAndModelNumberWithLock(Long id, String modelNumber);

型