What is the difference between FetchType.EAGER and FetchType.LAZY in Hibernate?

Understanding the Difference Between FetchType.EAGER and FetchType.LAZY in Hibernate

When working with entities in Hibernate, it is crucial to understand the difference between FetchType.EAGER and FetchType.LAZY. These two options determine how related entities are fetched from the database.

FetchType.EAGER:

With FetchType.EAGER, related entities are loaded immediately along with the main entity. This means that all related data is fetched from the database in a single query. While this can be convenient in some cases as it reduces the number of database queries, it can also lead to performance issues if there are large amounts of data or unnecessary data being fetched.

FetchType.LAZY:

On the other hand, FetchType.LAZY loads related entities only when they are explicitly accessed in the code. This can help improve performance by loading data only when needed. Lazy loading is especially useful in scenarios where fetching all related data upfront is not necessary or could lead to undesirable performance impacts.

When choosing between FetchType.EAGER and FetchType.LAZY, it is important to consider the specific requirements of your application and the performance implications of each option.

By understanding and appropriately utilizing FetchType.EAGER and FetchType.LAZY in Hibernate, you can optimize your data retrieval process and enhance the overall performance of your application.