Fetching all Objects at once

Hi!

Currently I'm facing a challenge that I've not been able 
to find a solution for as of now.

I got two entities in my model, key and value. For 1 key I 
can have an infinite amount of values (one for every user 
that uses the application). So when I programmatically 
fetch the key and access a value to it EO seems to fetch 
all the values in that relationship (NSArray) at once. 

Since the number of values is rather large that takes 
quite some time. So what I'm looking for is a way to keep 
EO from getting all the objects that are related to the 
key I got and rather only fetch the ones I'm actually 
accessing one at a time.

Is there a way to do that?

Thanks!
Oliver