JPA merge vs. persist

java jpa merge entitymanager persist
phewataal picture phewataal · Dec 12, 2011 · Viewed 79.7k times · Source

So far, my preference has been to always use EntityManager's merge() take care of both insert and update. But I have also noticed that merge performs an additional select queries before update/insert to ensure record does not already exists in the database.

Now that I am working on a project requiring extensive (bulk) inserts to the database. From a performance point of view does it make sense to use persist instead of merge in a scenario where I absolutely know that I am always creating a new instance of objects to be persisted?

Answer

Óscar López picture Óscar López · Dec 12, 2011

It's not a good idea using merge when a persist suffices - merge does quite a lot more of work. The topic has been discussed on StackOverflow before, and this article explains in detail the differences, with some nice flow diagrams to make things clear.

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