我使用hibernate spring-data-jpa和querydsl进行分页,并使用@BatchSize(size = 10)只进行一次数据库往返.

@Entity

@Table(name = "appel_offre",catalog = "ao")

public class AppelOffre implements java.io.Serializable {

….

@OneToMany(fetch = FetchType.LAZY,mappedBy = "appelOffre")

@BatchSize(size=10)

public Set

并且：

@Entity

@Table(name = "ao_activite",catalog = "ao")

public class AoActivite implements java.io.Serializable {

…..

@ManyToOne(fetch = FetchType.LAZY)

@JoinColumn(name = "ID_ACTIVITE",nullable = false)

@BatchSize(size=10)

public Activite getActivite() {

return this.activite;

}

我的查询

JPAQuery query = new JPAQuery(entityManager).from(ao)

.leftJoin( ao.acheteur,ach ).fetch()

.leftJoin( ao.aoActivites,ao_ac )

.leftJoin( ao_ac.activite,ac )

.offset(…).limit(…).list(..);

但是在日志中有很多往返数据库：

1 – round-trip

…..

Hibernate: select … from ao.ao_activite aoactivite0_ where aoactivite0_.ID_APPEL_OFFRE in (?,?,?)

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

2 – round-trip

…..

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

3 – round-trip

…..

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

4 – round-trip

…..

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

5 – round-trip

…..

6 – round-trip

…..

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

7 – round-trip

……

8 – round-trip

…..

Hibernate: select … from ao.activite activite0_ where activite0_.ID_ACTIVITE=?

9 – round-trip

…..

10 – round-trip

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