What is the most efficient way to remove all instances in an entity in Core Data?

Question

I found from this post I can remove all instances of an entity by fetching them all and deleting them all. Isn't there any more efficient way to do removal? My consideration is I will have thousand of records within that entity.

Answer 1

There's no more efficient way, because CoreData is an ORM layer, not a database. Therefore you deal with objects and if you want them gone, you have to delete them.

A trick you may want to investigate is creating a parent object that would have a one-to-many relationship with the objects to delete. You could basically have only one of those that points to every entry in your big table. Set the cascade delete option on the relationship in your model. Then when comes time to purge, you just delete the parent object. Because of lazy loading, it won't try to load your other objects.

This being said, I haven't tried it myself, but it seems like a viable option.

Answer 2

In a special case where all instances of this entity are self-contained, it would be quicker to delete the backing file and re-initialize the management objects. This only works if your data can be arranged so that the temporary stuff is within its own store.

Otherwise, you'd probably get better results by using direct database access instead of core data.