Which Hibernate Saving Strategy is Right for You?

Saving Strategies in Hibernate: Unraveling the Differences

In Hibernate, developers have an array of methods at their disposal for persisting objects to the database. This article unravels the intricacies of each method, providing guidance on when and why to use them.

save(), update(), saveOrUpdate() and saveOrUpdateCopy()

save(): Saves an entity to the database, assigning an identifier if it doesn't exist. Essentially, it performs an update if the identifier already exists.

update(): Attempts to persist an entity with an existing identifier. If no identifier exists, an exception is typically thrown.

saveOrUpdate(): Dynamically chooses between save() and update() based on whether the entity has an identifier.

saveOrUpdateCopy(): (deprecated) No longer in use, replaced by merge().

merge()

merge(): Employed for updates when dealing with transient (unmanaged) or detached entities. It merges the changes into the session and updates the database accordingly.

persist()

persist(): Similar to merge(), but used strictly for saving transient entities without returning the generated identifier.

Choosing the Right Method

The choice depends on the state of the entity and the desired behavior:

• save(): Ideal for saving a new entity
• update(): For updating an existing entity with an identifier
• saveOrUpdate(): Convenient for cases where the existence of an identifier is unknown
• merge(): Used with transient or detached entities (when direct update() is not applicable)
• persist(): For saving transient entities without retrieving the generated identifier

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