Hibernate's `save`, `persist`, `update`, `saveOrUpdate`, and `merge`: When to Use Which?

Saving Options in Hibernate

Hibernate provides multiple methods for persisting data into a database, each serving a specific purpose. Understanding these differences is crucial for optimal database interaction.

save

Persists a new entity, assigning a unique identifier if none exists. If an identifier is present, it performs an update operation.

update

Attempts to persist an entity with an existing identifier. If the identifier is missing, an exception is thrown.

saveOrUpdate

Dynamically calls either save or update based on the existence of an identifier. If no identifier is present, it uses save; otherwise, it uses update.

saveOrUpdateCopy

Deprecated and replaced by merge.

merge

Used for updating or saving transient or detached entities. Transient objects are new objects that have never been persisted, while detached objects have been previously persisted but are no longer associated with a Hibernate session.

persist

Specifically designed for saving transient objects. Unlike save, it does not return the generated identifier.

Choosing the Right Method

save: For saving new entities or updating records based on an identifier.

update: For explicitly updating existing entities.

saveOrUpdate: For scenarios where you are uncertain if an entity is new or existing.

merge: For updating or saving transient or detached entities.

persist: For saving new entities without the need for identifier retrieval.

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