# @Immutable

> Reference: [@Immutable in Hibernate](https://www.baeldung.com/hibernate-immutable)

### What is @Immutable?

* When this annotation is added to an `Entity`, updates will not work
* When added to a `Collection`, add & delete will not work

### Behavioral Changes When @Immutable Annotation is Added

* INSERT
  * No changes
* UPDATE
  * Hibernate does not throw an exception and simply `ignores` the UPDATE operation execution
  * Separate configuration is needed to trigger an exception
* DELETE
  * No changes

### Things to Note

* `@Immutable` entities can still be updated via JPQL or Criteria
* However, starting from **5.2.17**, updates have been blocked but only a WARNING is logged
  * To also trigger an error, set the following property

    ```java
    hibernate.query.immutable_entity_update_query_handling_mode=exception
    ```