What is the most efficient way to setup relationships between thousands of objects in Core Data?

Question

Let's say I have inserted 10.000 Book entities and 10.000 Author entities, and need to setup one to one relationships between them. Both entities have an attribute called bookID. I do this:

1. Fetch all Books, sorted by bookID
2. Fetch all Authors, sorted by bookID
3. Enumerate the books array, and if currentBook.bookID == currentAuthor.bookID, then currentBook.author = currentAuthor. Repeat this for all books. At every 1000th book for which a relationship was just set, save the context (otherwise even more memory is consumed).

My problem is memory allocation going overboard. How do I limit that? I tried [fetchRequest setBatchSize:], setFetchLimit: in conjunction with setFetchOffset:, with no luck.

Answer 1

I don't think you are conceptualizing your data model correctly. An attribute "bookID" shouldn't really be in the Author Entity. Also it seems strange to have a one to one relationship in both ways. More likely you would want to have a one-to-many relationship from Author to Book (an author could write multiple books), and potentially even a one-to-many relationship in the opposite direction as well (a book could have multiple authors, although that is up to you).