What is the difference between FetchType.LAZY and FetchType.EAGER? FetchType.LAZY और FetchType.EAGER में क्या अंतर है?

FetchType.LAZY defers loading a related entity or collection until it is actually accessed in code, returning a proxy initially. FetchType.EAGER loads the related data immediately, in the same query or an immediate follow-up query, whenever the owning entity is loaded.

Lazy loading is generally preferred for performance since it avoids fetching unnecessary data, but accessing a lazy association outside an active persistence context (e.g. after the transaction closes) throws a LazyInitializationException. @OneToMany and @ManyToMany default to LAZY; @ManyToOne and @OneToOne default to EAGER, which is why they're often explicitly overridden to LAZY.

@ManyToOne(fetch = FetchType.LAZY)
@JoinColumn(name = "author_id")
private Author author;