# Ehcache Hibernate 2nd-level cache - Element for key is Null and N+1 query issue

**URL:** <https://discourse.hibernate.org/t/ehcache-hibernate-2nd-level-cache-element-for-key-is-null-and-n-1-query-issue/210>\
**Category:** Hibernate ORM\
**Created:** [February 8, 2018, 10:09am UTC](https://discourse.hibernate.org/t/ehcache-hibernate-2nd-level-cache-element-for-key-is-null-and-n-1-query-issue/210 "2018-02-08T10:09:17Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![shiva](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/shiva/32/760_2.png) [@shiva](https://discourse.hibernate.org/u/shiva)\
**Post date:** [February 8, 2018, 10:09am UTC](https://discourse.hibernate.org/t/ehcache-hibernate-2nd-level-cache-element-for-key-is-null-and-n-1-query-issue/210/1 "2018-02-08T10:09:17Z")

</div>

Hello, I am running a hibernate criteria query and setting the query cache using QueryHints. After the first execution, I see the error as below.

Please advise what this error is indicating. During first time execution, I dont see any N+1 queries as below, however, all subsequent requests are triggering these queries.

```auto
14:44:27,003 - DEBUG - org.hibernate.cache.ehcache.internal.regions.EhcacheGeneralDataRegion - key: EMPLOYEE 
14:44:27,003 - DEBUG - org.hibernate.cache.ehcache.internal.regions.EhcacheGeneralDataRegion - Element for key EMPLOYEE is null
14:44:27,003 - DEBUG - org.hibernate.cache.ehcache.internal.regions.EhcacheGeneralDataRegion - key: DEPARTMENT
14:44:27,003 - DEBUG - org.hibernate.cache.ehcache.internal.regions.EhcacheGeneralDataRegion - Element for key DEPARTMENT is null
14:44:27,003 - DEBUG - org.hibernate.cache.ehcache.internal.regions.EhcacheGeneralDataRegion - key: ADDRESS
14:44:27,003 - DEBUG - org.hibernate.cache.ehcache.internal.regions.EhcacheGeneralDataRegion - Element for key ADDRESS is null
14:44:27,003 - DEBUG - org.hibernate.cache.internal.StandardQueryCache - Returning cached query results
Hibernate: 
    /* load com.test.Employee */ select
        emp0_.ID as EMP17_0_    
    from
        EMPLOYEE emp0_ 
    where
        emp0_.NAME=?
Hibernate: 
    /* load com.test.Department */ select
        dept0_.deptid as dept1_12_3_
    from
        DEPARTMENT dept0_     
    where
        dept0_.ID=?
Hibernate: 
    /* load com.test.Employee */ select
        emp0_.ID as EMP17_0_    
    from
        EMPLOYEE emp0_ 
    where
        emp0_.NAME=?
Hibernate: 
    /* load com.test.Department */ select
        dept0_.deptid as dept1_12_3_
    from
        DEPARTMENT dept0_     
    where
        dept0_.ID=?

```

---

<div class="post-metadata">

**Author:** ![vlad](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/vlad/32/658_2.png) [@vlad](https://discourse.hibernate.org/u/vlad)\
**Post date:** [February 8, 2018, 10:20am UTC](https://discourse.hibernate.org/t/ehcache-hibernate-2nd-level-cache-element-for-key-is-null-and-n-1-query-issue/210/2 "2018-02-08T10:20:39Z")

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Most likely this happens because, by default, [`@ManyToOne` and `@OneToOne` associations are using `FetchType.EAGER`](https://vladmihalcea.com/eager-fetching-is-a-code-smell/).

So, in your case, you have an entity that was cached. But when you fetch it, it tries to load all EAGER associations as well, which are not cached, like:

- `Employee`
- `Departement`
- `Address`

To fix it, you have to options:

1. Either you set all to `FetchType.LAZY` for all these `@ManyToOne` and `@OneToOne` associations

2. Or, you cache all these entities as well, meaning that you need to provide the Hibernate `@Cache` annotation which provides the cache concurrency strategy:

---

<div class="post-metadata">

**Author:** ![shiva](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/shiva/32/760_2.png) [@shiva](https://discourse.hibernate.org/u/shiva)\
**Post date:** [February 8, 2018, 6:22pm UTC](https://discourse.hibernate.org/t/ehcache-hibernate-2nd-level-cache-element-for-key-is-null-and-n-1-query-issue/210/3 "2018-02-08T18:22:00Z")

</div>

Thank you Vlad. Could you also please clarify below queries in this regards.

1. I’m using ehcache and want to implement distribution caching using ehcache. After referring your book, I learned hazelcast is an option. Please let me know if there are any code implementation challenges going with ehcache here other than the infra constraints you mentioned.

2. I know you mentioned eager initialization smells. I have @OneToMany Mapping as well. Do you suggest me to go LAZY initialize on this as well considering the best practice.

Thank you.

---

<div class="post-metadata">

**Author:** ![vlad](https://yyz1.discourse-cdn.com/flex035/user_avatar/discourse.hibernate.org/vlad/32/658_2.png) [@vlad](https://discourse.hibernate.org/u/vlad)\
**Post date:** [February 8, 2018, 6:39pm UTC](https://discourse.hibernate.org/t/ehcache-hibernate-2nd-level-cache-element-for-key-is-null-and-n-1-query-issue/210/4 "2018-02-08T18:39:16Z")

</div>

1. You should check and see if EhCache or Hazelcast suits you better. There’s also Infinispan as well, which is very well integrated with Hibernate.
2. Using LAZY by default is a very good practice. You can always swicth from LAZY to EAGER on a query-basis, but not the other way around.