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What is the use of FetchMode lazy in Hibernate criteria?

What is the use of FetchMode lazy in Hibernate criteria?

The FetchType. LAZY tells Hibernate to only fetch the related entities from the database when you use the relationship. This is a good idea in general because there’s no reason to select entities you don’t need for your uses case. You can see an example of a lazily fetched relationship in the following code snippets.

What is FetchMode Subselect?

The FetchMode.SUBSELECT. use a subselect query to load the additional collections. Hibernate docs: If one lazy collection or single-valued proxy has to be fetched, Hibernate will load all of them, re-running the original query in a subselect. This works in the same way as batch-fetching but without the piecemeal …

What is subselect fetching in Hibernate?

The SUBSELECT fetch mode is used to minimize the number of SELECT statements executed to fetch the related entities. If you first fetch the owner entities and then try to access the associated owned entities, without SUBSELECT, Hibernate will issue an additional SELECT statement for every one of the owner entities.

What does FetchType lazy mean?

FetchType. LAZY: It fetches the child entities lazily, that is, at the time of fetching parent entity it just fetches proxy (created by cglib or any other utility) of the child entities and when you access any property of child entity then it is actually fetched by hibernate.

What is FetchMode Subselect value?

What are different fetching ways in Hibernate?

Different Fetch modes supported by Hibernate

  • 1) FetchMode JOIN.
  • 2) FetchMode SELECT(default)
  • 3) FetchMode SELECT with Batch Size.
  • 4) FetchMode SUBSELECT.
  • Code to define the fetching strategy.
  • FetchMode JOIN.
  • FetchMode SELECT(default)
  • FetchMode SELECT with Batch Size.

What is the difference between fetch type eager and lazy?

The EAGER strategy is a requirement on the persistence provider runtime that data must be eagerly fetched. The LAZY strategy is a hint to the persistence provider runtime that data should be fetched lazily when it is first accessed.

How to use in hibernate?

FetchMode.SELECT has an optional configuration annotation using the @BatchSize annotation: Hibernate will try to load the orders collection in batches defined by the size parameter. In our example, we have just five orders so one query is enough.

What are the fetch types in Hibernate Java?

Hibernate Fetch types. 1) FetchMode JOIN. Eager loading which loads all the collections and relations at the same time. 2) FetchMode SELECT (default) 3) FetchMode SELECT with Batch Size. 4) FetchMode SUBSELECT. 3. Another query to load the Address collections for other 10 Customers.

What does lazy loading do in hibernate fetch?

Modify above annotated class with @Fetch (FetchMode.SELECT) This is also called Lazy loading which means loads the collections and relations only when required It loads only Customer when we request the Customer, it will not load the addresses until we request for it.

Which is the fetching strategy in hibernate generated SELECT statement?

Hibernate has few fetching strategies to optimize the Hibernate generated select statement, so that it can be as efficient as possible. The fetching strategy is declared in the mapping relationship to define how Hibernate fetch its related collections and entities.