# The @ElementCollection values inside an @Embeddable VO are not being fetched with a left outer join (eager fetch) as expected

**URL:** <https://discourse.hibernate.org/t/the-elementcollection-values-inside-an-embeddable-vo-are-not-being-fetched-with-a-left-outer-join-eager-fetch-as-expected/10788>\
**Category:** Hibernate ORM\
**Created:** [December 13, 2024, 1:50am UTC](https://discourse.hibernate.org/t/the-elementcollection-values-inside-an-embeddable-vo-are-not-being-fetched-with-a-left-outer-join-eager-fetch-as-expected/10788 "2024-12-13T01:50:08Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![wishgone](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/wishgone/32/3689_2.png) [@wishgone](https://discourse.hibernate.org/u/wishgone)\
**Post date:** [December 13, 2024, 1:50am UTC](https://discourse.hibernate.org/t/the-elementcollection-values-inside-an-embeddable-vo-are-not-being-fetched-with-a-left-outer-join-eager-fetch-as-expected/10788/1 "2024-12-13T01:50:08Z")

</div>

There is an `AEntity` that contains a `BVO`. The `BVO` represents a few columns of the `AEntity`.

Additionally, there is a `CVO`, which is a separate table and exists inside the `BVO`. The `CVO` is managed as a collection type with a 1:N relationship.

When `AEntity` is queried, I want it to be fetched with a single query using a left join. However, it is being fetched lazily instead.

I’d like to understand what the problem is.

Here’s the code:

```auto
@Entity
@Table(name = "a_table")
public class AEntity {

    @Id
    private Long id;

    @Embedded
    private BVo bVo;
}

```

```auto
@Embeddable
public class BVo {

    @ElementCollection(fetch = FetchType.EAGER)
    @Fetch(FetchMode.JOIN)
    @CollectionTable(name = "c_table", joinColumns = @JoinColumn(name = "a_id"))
    private List<CVo> cVoList = new ArrayList<>();

}

```

```auto
@Embeddable
public class CVo {

}

```

---

<div class="post-metadata">

**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [December 13, 2024, 9:36am UTC](https://discourse.hibernate.org/t/the-elementcollection-values-inside-an-embeddable-vo-are-not-being-fetched-with-a-left-outer-join-eager-fetch-as-expected/10788/2 "2024-12-13T09:36:44Z")

</div>

What version of Hibernate ORM are you using? How are you fetching `AEntity`? What SQL queries are generated?

---

<div class="post-metadata">

**Author:** ![wishgone](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/wishgone/32/3689_2.png) [@wishgone](https://discourse.hibernate.org/u/wishgone)\
**Post date:** [December 13, 2024, 3:39pm UTC](https://discourse.hibernate.org/t/the-elementcollection-values-inside-an-embeddable-vo-are-not-being-fetched-with-a-left-outer-join-eager-fetch-as-expected/10788/3 "2024-12-13T15:39:50Z")

</div>

Hello @beikov,

I am using Hibernate version 6.5.3.Final. Regarding fetching `AEntity`, I’m not entirely sure if I understand it correctly, but I’m retrieving data using Spring query methods as shown below:

```auto
AEntityRepository.findAll();
AEntityRepository.findAllById(Long id);

```

When I query in this way, the generated queries result in an N+1 issue, as shown below:

```auto
select *
from a_table
where id = 1;

select *
from c_table
where a_id = 1;

```

`BVO` is a simple class containing only a few fields of `AEntity` (`a_table`), and I expected the `List<CVo>` to work with a `@Fetch(FetchMode.JOIN)` annotation, avoiding the N+1 issue and instead working as a `left join fetch` query like the following:

```auto
select *
from a_table left join c_table on a.id = c.a_id
where c.id = 1;

```

I’m not sure if I misunderstood something or if I’m missing some configuration.

Thank you for your attention.

---

<div class="post-metadata">

**Author:** ![beikov](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/beikov/32/258_2.png) [@beikov](https://discourse.hibernate.org/u/beikov)\
**Post date:** [December 13, 2024, 8:01pm UTC](https://discourse.hibernate.org/t/the-elementcollection-values-inside-an-embeddable-vo-are-not-being-fetched-with-a-left-outer-join-eager-fetch-as-expected/10788/4 "2024-12-13T20:01:50Z")

</div>

This is not a forum for Spring Data questions. You will have to ask Spring people about what is happening under the hood.  
I can tell you that if you use `EntityManager#find`, the fetch type will contribute into the SQL query. If you use a HQL/Criteria query e.g. `EntityManager#createQuery`, the fetch type won’t contribute to the SQL query, but will result in this sort of N+1 queries.  
To solve this, you can use an entity graph which will contribute fetches to the SQL query in both cases or use an explicit HQL query with explicit join fetches.