title: Realm Files in Memory For Production Applications
body: <p>So, I am little confused about how multiple Realms would work in a single application for a user accessing all of the information in the application.</p>
  
  <p>For example, if Instagram used Realm, am I, as a user, accessing multiple Realms per feature (search, main feed, messages, etc.)? Under current limitations, Realm's fourth stated (current) limitation says </p>
  
  <p><strong>Any single Realm file cannot be larger than the amount of memory your application would be allowed to map in iOS — this changes per device, and depends on how fragmented the memory space is at that point in time (there is a radar open about this issue: (rdar://17119975)). If you need to store more data, you can map it over multiple Realm files.</strong> </p>
  
  <p>I take this to mean there is limited space on the device and therefore I either need one Realm per user who may access any and all data or that I still need a backend to store data. Is this correct?</p>
  
  <p>The database part makes sense, but how would <strong>map it over multiple Realm files</strong> even work?</p>