Question

我正在使用基于Spring的java Web应用程序。为了访问数据库，我使用Spring Data 1.11.6.RELEASE和Hibernate 5.2。我的数据库是MySQL 5.7

涉及的实体是 - 具有一些共同字段的BaseEntity

@MappedSuperclass
public abstract class BaseEntity implements Serializable {

    @Id
    @GeneratedValue(strategy=GenerationType.IDENTITY)
    private Long id;

    @ManyToOne
    @CreatedBy
    private WebUser createdBy;
    ...
    ...
}

@Entity
@Table(name = "advertising")
public class Advertising extends BaseEntity {

    @ManyToOne
    private AdvertisingStatus status;

    ...
    ...
}

最后是WebUser

@Entity
@Table(name = "web_user",uniqueConstraints = @UniqueConstraint(columnNames = {"mail"}))
public class WebUser extends BaseEntity {

    @ManyToOne
    private WebUserStatus webUserStatus;

    ...
    ...

我不明白为什么从这个HQL和具有maxRows = 75

的Pageable对象开始

from Advertising a 
where a.status in (:adStatuses) 
    and a.createdBy.webUserStatus.id = :webUserStatus 
order by orderDate desc

生成的查询如下

select *
from advertising advertisin0_ 
    cross join web_user webuser1_ where advertisin0_.createdBy_id=webuser1_.id 
    and (advertisin0_.status_id in (1 , 9)) 
    and webuser1_.webUserStatus_id=1
order by advertisin0_.orderDate desc limit 75

我关心的是交叉连接，它应该比标准连接慢。是否可以进行标准连接而不是交叉连接？

Spring数据 - 意外交叉加入

0 个答案: