[hibernate-dev] FetchMode.SELECT

Should it be possible to force an eager association to be loaded by a
separate query using @Fetch(FetchMode.SELECT)?

I thought that Hibernate supported that for an EAGER association, but I see
the documentation for FetchMode.SELECT
<https://docs.jboss.org/hibernate/orm/5.4/userguide/html_single/Hibernate_User_Guide.html#fetching-fetch-annotation>
says:

"SELECT
The association is going to be fetched lazily using a secondary select for
each individual entity, collection, or join load. It’s equivalent to
JPA FetchType.LAZY fetching strategy."

The reason I ask is because I am trying to wrap up HHH-13085, which will
change derived IDs mapped as a one-to-one association, currently loaded by
a separate query, to instead be loaded in the same query that loads the
dependent entity. I want to ensure that it is possible to revert back to
loading that one-to-one association in a separate query after HHH-13085 is
fixed.

Currently, a StackOverflowError is thrown when loading an entity with an ID
that is an bidirectional eager one-to-one association has FetchMode.SELECT
mapped.

@Entity(name = "Foo")public class Foo implements Serializable {

    @Id
    @GeneratedValue
    private Long id;

    @OneToOne(mappedBy = "foo", cascade = CascadeType.ALL)
    private Bar bar;
}

@Entity(name = "Bar")public class Bar implements Serializable {
@Id
    @OneToOne(fetch = FetchType.EAGER)
    @Fetch(FetchMode.SELECT)
    @JoinColumn(name = "BAR_ID")
    private Foo foo;
}


According to the documentation, it sounds like @Fetch(FetchMode.SELECT)
should make the association lazy. Is that really correct?

Could someone please clarify the expected behavior?

I created HHH-14390 <https://hibernate.atlassian.net/browse/HHH-14390> for
the StackOverflowError. I've pushed some FailureExpected tests
<https://github.com/hibernate/hibernate-orm/commit/b40d1251e385a5fdb018f9583a83c472d6da4e8f>
that reproduce this issue.

Thanks,
Gail
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