[hibernate-issues] [Hibernate-JIRA] Commented: (HHH-5165) FetchMode=Eager not respected, N+1 SELECT Problem

[Gail Badner (JIRA)]

    [ http://opensource.atlassian.com/projects/hibernate/browse/HHH-5165?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=36717#action_36717 ] 

Gail Badner commented on HHH-5165:
----------------------------------

Does this happen using 3.5.1? 

If so, please check to see if it has already been reported for 3.5.x:
http://opensource.atlassian.com/projects/hibernate/secure/IssueNavigator.jspa?mode=hide&requestId=11080

Thanks,
Gail

> FetchMode=Eager not respected, N+1 SELECT Problem
> -------------------------------------------------
>
>                 Key: HHH-5165
>                 URL: http://opensource.atlassian.com/projects/hibernate/browse/HHH-5165
>             Project: Hibernate Core
>          Issue Type: Bug
>          Components: core
>    Affects Versions: 3.3.2
>         Environment: (as Maven artifacts)
> org.hibernate:hibernate-core:jar:3.3.2.GA
> org.hibernate:hibernate-annotations:jar:3.4.0.GA
> org.hibernate:ejb3-persistence:jar:1.0.2.GA
> org.hibernate:hibernate-validator:jar:3.1.0.GA
> org.hibernate:hibernate-commons-annotations:jar:3.1.0.GA
> org.hibernate:hibernate-search:jar:3.1.0.GA
> org.hibernate:hibernate-entitymanager:jar:3.4.0.GA
>            Reporter: David Bernhard
>            Priority: Minor
>
> Two classes A, B with 1:n relationship. Fetching all instances of B with an empty DetachedCriteria instance does not repsect FetchMode.JOIN but issues a SELECT for each A (N+1 SELECT problem).
> This causes the bug:
> findByCriteria(DetachedCriteria.forClass(B.class));
> This works - but I need that second setFetchMode:
> findByCriteria(DetachedCriteria.forClass(B.class)
>   .setFetchMode("a", FetchMode.JOIN)
>   .setFetchMode("a.bs", FetchMode.JOIN)
> );
> HQL works too. Here are two classes that cause the bug:
> @Entity @Table(name = "A")
> @SequenceGenerator(name = "keyid_generator", sequenceName = "A_sequence")
> public class A extends AbstractIntKeyIntOptimisticLockingDto {
>    private String name;
>    private Set<B> bs;
>    @OneToMany(mappedBy = "a", fetch = FetchType.EAGER)
>    @Fetch(FetchMode.JOIN)
>    public Set<B> getBs() {
>       return bs;
>    }
>    public void setBs(Set<B> bs) {
>       this.bs = bs;
>    }
>    public String getName() {
>       return name;
>    }
>    public void setName(String name) {
>       this.name = name;
>    }
> }
> @Entity @Table(name = "B")
> @SequenceGenerator(name = "keyid_generator", sequenceName = "B_sequence")
> public class B extends AbstractIntKeyIntOptimisticLockingDto {
>    private String name;
>    private A a;
>    @ManyToOne(fetch = FetchType.EAGER)
>    @JoinColumn(name = "a", nullable = false,
>    unique = false, updatable = false)
>    @Fetch(FetchMode.JOIN)
>    public A getA() {
>       return a;
>    }
>    public void setA(A a) {
>       this.a = a;
>    }
>    public String getName() {
>       return name;
>    }
>    public void setName(String name) {
>       this.name = name;
>    }
> }

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