JPA Hibernate Lazy loading not working as expected

Question

I have following two entities with bidirectional relationship @OneToMany and @ManyToOne. When I query child table with join query as shown below, hibernate automatically query StandardDimension (Parent) table for each MinuteData (Child table) to load @ManyToOne relationship even though it is marked as lazy loading. This is causing DB performance issue. Can you please help me resolve this issue so for each MinuteData it will not load standard dimension record ? I am using JPA 2.0 and hibernate-core-4.1.1.Final. Any help will be greatly appreciated. How can stop hibernate from loading StandardDimension objects ?

@Query("SELECT md FROM StandardDimension sd ,MinuteData md where  sd.dimensionAK = md.dimensionFK and sd.app = :applicationId and md.timeBucket between :startTime and :endTime ")
public List<MinuteData> findMinuteDataByTimeBucket( @Param("startTime") Date startTime,     @Param("endTime") Date endTime, @Param("applicationId") String applicationId); 



@Entity (name="StandardDimension")
@Table (name="STANDARD_DIMENSION")
public class StandardDimension implements Serializable {

    @OneToMany (targetEntity=MinuteData.class, fetch=FetchType.LAZY, mappedBy="dimensionFK", cascade=CascadeType.REMOVE)
    private Set<MinuteData> muniteDateDimensionViaFK = new HashSet<MinuteData>();  
}

@Entity (name="MinuteData")
@Table (name="MINUTE_DATA")
public class MinuteData implements Serializable {
........

    @ManyToOne (fetch=FetchType.LAZY)
    @JoinColumn(name="DIMENSION_FK", referencedColumnName = "DIMENSION_AK", nullable=false , unique=false , insertable=true, updatable=true)
    private StandardDimension dimensionFK;  
.........
    }
Here is SQL Statement form console:
    Hibernate: 
        select
            minutedata1_.minute_data_pk as minute1_1_,
            minutedata1_.created_date as created2_1_,
            minutedata1_.data_obj as data3_1_,
            minutedata1_.dimension_fk as dimension6_1_,
            minutedata1_.modified_date as modified4_1_,
            minutedata1_.time_bucket as time5_1_ 
        from
            standard_dimension standarddi0_,
            minute_data minutedata1_ 
        where
            standarddi0_.dimension_ak=minutedata1_.dimension_fk 
            and standarddi0_.app=? 
            and (
                minutedata1_.time_bucket between ? and ?
            )
    Hibernate: 
        select
            standarddi0_.standard_dimensions_pk as standard1_2_0_,
            standarddi0_.app as app2_0_,
            standarddi0_.created_date as created3_2_0_,
            standarddi0_.data_center as data4_2_0_,
            standarddi0_.dimension_ak as dimension5_2_0_,
            standarddi0_.env as env2_0_,
            standarddi0_.last_seen as last7_2_0_,
            standarddi0_.modified_date as modified8_2_0_,
            standarddi0_.server as server2_0_,
            standarddi0_.app_version as app10_2_0_ 
        from
            standard_dimension standarddi0_ 
        where
            standarddi0_.dimension_ak=?

have you checked the getter setter of your entity, sometimes logic in accessor methods involving some child entity causes select statements. — Ashish Thukral
I double checked entities and there is no hashcode or equals method that access parent (StandardDimension). Let me know if there any other thing I need to check. — Bmis13
hey @Bmis13, i know it's been almost 3 years, but i just wanted to know if you did find any solution to this problem? — jon

Manuel Darveau Manuel Darveau · Accepted Answer · 2013-09-27T01:32:43

Are you 100% sure that nothing triggers a lazy loading of StandardDimension? Sometime it's trigger by a too gready implementation of equals or hashcode.

If not, can you try your query using the Criteria API just to see if it makes any difference?

JPA Hibernate Lazy loading not working as expected

1 Answers