Question

我在Spring Data JPA中遇到一些简单查询的性能问题。

型号：

@Entity
public class LogEntry {
    ..
    @NotNull
    @ElementCollection(fetch = FetchType.EAGER)
    private List<String> parameters;

    @ManyToOne
    private Guest guest;
    ..
}

存储库：

Page<LogEntry> findByGuestOrderByCreationDateDesc(Guest guest, Pageable pageable);

我想显示包含所有参数的日志条目列表。但是查询速度非常慢。找到所有条目后，它开始查询每个条目的参数。

日志显示了很多这些行：

Hibernate: select parameters0_.LogEntry_id as LogEntry1_8_0_, parameters0_.parameters as paramete2_9_0_ from LogEntry_parameters parameters0_ where parameters0_.LogEntry_id=?

我正在寻找一种改进查询的方法。我尝试使用连接提取但没有成功。

@Query("select l from LogEntry l join fetch l.parameters where l.guest = ?1 order by l.creationDate desc")


Caused by: org.hibernate.QueryException: query specified join fetching, but the owner of the fetched association was not present in the select list [FromElement{explicit,collection join,fetch join,fetch non-lazy properties,classAlias=null,role=domain.guest.LogEntry.parameters,tableName={none},tableAlias=parameters1_,origin=null,columns={,className=null}}] [select count(l) from domain.guest.LogEntry l join fetch l.parameters where l.guest = ?1]

Answer 1

您可以尝试以下代码。

@Query("select logEntry from LogEntry logEntry join fetch logEntry.parameters as params join fetch logEntry.guest as guest where guest.id = :guestId order by logEntry.creationDate desc")
Page<LogEntry> findByGuestOrderByCreationDateDesc(@Param Long guestId, Pageable pageable);

Spring Data JPA - 使用ElementCollection查询 - 低性能

1 个答案: