array of structures, or structure of arrays?

Question

Hmmm. I have a table which is an array of structures I need to store in Java. The naive don\'t-worry-about-memory approach says do this:

public class Record          


        

Answer 1

Notice that the second approach might have negative impact on caching behaviour. If you want to access a single record at a time, you'd better have that record not scattered all across the place.

Also, the only memory you win in the second approach, is (possibly) due to member alignment. (and having to allocate a separate object). Otherwise, they have exactly the same memory use, asymptotically. The first option is much better due to locality, IMO